Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
119 B ABC SAMPLE DESIGN CALCULATIONS
120 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT APPENDIX B ABC SAMPLE DESIGN CALCULATIONS Three design examples are presented in this appendix, as follows: ï· Sample Calculation 1: Decked Steel Girder Design for ABC ï· Sample Calculation 2: Decked Precast Prestressed Concrete Girder Design for ABC ï· Sample Calculation 3: Precast Pier Design for ABC The design examples illustrate the design steps involved in the ABC design process as given in the breakdown below. The ABC design philosophy and design criteria have been described. Annotations have been used for the purpose of providing explanation of the design steps. LRFD code references have also been included to guide the reader. Sample Calculation 1: Decked Steel Girder Design for ABC B-3 General: 1. Introduction 2. Design Philosophy 3. Design Criteria 4. Material Properties 5. Load Combinations Girder Design: 6. Beam Section Properties 7. Permanent Loads 8. Precast Lifting Weight 9. Live Load Distribution Factors 10. Load Results 11. Flexural Strength 12. Flexural Strength Checks 13. Flexural Service Checks 14. Shear Strength 15. Fatigue Limit States 16. Bearing Stiffeners 17. Shear Connectors Deck Design: 18. Slab Properties 19. Permanent Loads 20. Live Loads 21. Load Results 22. Flexural Strength Capacity Check 23. Longitudinal Deck Reinforcing Design 24. Design Checks 25. Deck Overhang Design Continuity Design: 26. Compression Splice 27. Closure Pour Design
121 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Sample Calculation 2: Decked Precast Prestressed Concrete girder Design for ABC B-44 General: 1. Introduction 2. Design Philosophy 3. Design Criteria Girder Design: 4. Beam Section 5. Material Properties 6. Permanent Loads 7. Precast Lifting Weight 8. Live Load 9. Prestress Properties 10. Prestress Losses 11. Concrete Stresses 12. Flexural Strength 13. Shear Strength 14. Splitting Resistance 15. Camber and Deflections 16. Negative Moment Flexural Strength Sample Calculation 3a: Precast Pier Design for ABC (70â Span Straddle Bent) B-80 1. Bent Cap Loading 2. Bent Cap Flexural Design 3. Bent Cap Shear and Torsion Design 4. Column / Drilled Shaft Loading and Design 5. Precast Component Design Sample Calculation 3b: Precast Pier Design for ABC (70â Span Conventional Pier) B-115 1. Bent Cap Loading 2. Bent Cap Flexural Design 3. Bent Cap Shear and Torsion Design 4. Column / Drilled Shaft Loading and Design 5. Precast Component Design
122 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ABC SAMPLE CALCULATION â 1 Decked Steel Girder Design for ABC
123 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT CONCRETE DECKED STEEL GIRDER DESIGN FOR ABC This document shows the procedure for the design of a steel girder bridge with precast deck element for use in a rapid bridge replacement design in Accelerated Bridge Construction (ABC). This sample calculation is intended as an informational tool for the practicing bridge engineer. These calculations illustrate the procedure followed to develop a similar design but shall not be considered fully exhaustive. This sample calculation is based on the AASHTO LRFD Bridge Design Specifications (Fifth Edition with 2010 interims). References to the AASHTO LRFD Bridge Design Specifications are included throughout the design example. AASHTO references are presented in a dedicated column in the right margin of each page, immediately adjacent to the corresponding design procedure. An analysis of the superstructure was performed using structural modeling software. The design moments, shears, and reactions used in the design example are taken from the output, but their computation is not shown in the design example. BRIDGE GEOMETRY: Design member parameters: Deck Width: wdeck 47ft 2inï«ïºï½ C. to C. Piers: Length 70ftïºï½ Roadway Width: wroadway 44ftïºï½ C. to C. Bearings Lspan 67ft 10inï«ïºï½ Skew Angle: Skew 0degïºï½ Bridge Length: Ltotal 3 Lengthï 210 ftï½ïºï½ Deck Thickness td 10.5inïºï½ Stringer W30x99 Haunch Thickness th 2inïºï½ Stringer Weight ws1 99plfïºï½ Haunch Width wh 10.5inïºï½ Stringer Length Lstr Length 6 inïï 69.5 ftï½ïºï½ Girder Spacing spacingint 3ft 11inï«ïºï½ Average spacing of adjacent beams. This value is used so that effective deck width is not overestimated. spacingext 4ftïºï½
124 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT TABLE OF CONTENTS: General: 1. Introduction 2. Design Philosophy 3. Design Criteria 4. Material Properties 5. Load Combinations Girder Design: 6. Beam Section Properties 7. Permanent Loads 8. Precast Lifting Weight 9. Live Load Distribution Factors 10. Load Results 11. Flexural Strength 12. Flexural Strength Checks 13. Flexural Service Checks 14. Shear Strength 15. Fatigue Limit States 16. Bearing Stiffeners 17. Shear Connectors Deck Design: 18. Slab Properties 19. Permanent Loads 20. Live Loads 21. Load Results 22. Flexural Strength Capacity Check 23. Longitudinal Deck Reinforcing Design 24. Design Checks 25. Deck Overhang Design Continuity Design: 26. Compression Splice 27. Closure Pour Design
125 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 1. INTRODUCTION The design of this superstructure system follows AASHTO LRFD and is based on a bridge of three even spans, with no skew. The bridge has two 14-foot lanes and two 8-foot shoulders, for a total roadway width of 44' from curb to curb. The out-to-out width of the bridge is 47'-2". The bridge deck is precast reinforced concrete with overhangs at the outermost girders. The longitudinal girders are placed as simply supported modules, and made continuous with connection plates and cast-in-place deck joints. The design of the continuity at the deck joint is addressed in final sections of this example. The cross-section consists of six modules. The interior modules are identical and consist of two steel girders and a 7'-10" precast composite deck slab. Exterior modules include two steel girders and a 7'-11" precast composite deck slab, with F-shape barriers. Grade 50 steel is used throughout, and the deck concrete has a compressive strength of 5,000 psi. The closure pour joints between the modules use Ultra High Performance Concrete with a strength of 21,000 psi. The following sections detail the design of the steel girders, including constructability checks, fatigue design for infinite fatigue lift (unless otherwise noted), and bearing stiffener design. The diaphragms are not designed in detail. A brief deck design is also included, with focus on the necessary checks for this type of modular superstructure. Tips for reading this Design Example: This calculation was prepared with Mathcad version 14. Mathcad is a computational aide for the practicing engineer. It allows for repetitive calculations in a clear, understandable and presentable fashion. Other computational aides may be used in lieu of Mathcad. Mathcad is not a design software. Mathcad executes user mathematical and simple logic commands. Example 1: User inputs are noted with dark shaded boxes. Shading of boxes allows the user to easily find the location of a desired variable. Given that equations are written in mathcad in the same fashion as they are on paper, except that they are interactive, shading input cells allows the user to quicly locate inputs amongst other data on screen. Units are user inputs. Height of Structure: Hstructure 25ftïºï½ Example 2: Equations are typed directly into the workspace. Mathcad then reads the operators and executes the calculations. Panels are 2.5' Npanels Hstructure 2.5ft ïºï½ Npanels 10ï½ Example 3: If Statements are an important operator that allow for the user to dictate a future value with given parameters. They are marked by a solid bar and operate with the use of program specific logic commands.
126 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Operator offers discount per volume of panels Discount .75 Npanels 6ï³if .55 Npanels 10ï³if 1 otherwise ïºï½ Discount 0.6ï½ Example 4: True or False Verification Statements are an important operator that allow for the user to verify a system criteria that has been manually input. They are marked by lighter shading to make a distinction between the user inputs. True or false statements check a single or pairs of variables and return a Zero or One. Owner to proceed if discounts on retail below 60% Discount .55ï£ 1ï½ 2. DESIGN PHILOSOPHY The geometry of this superstructure uses modules consisting of two rolled steel girders supporting a segment of bridge deck cast along the girder lengths. It is assumed that the initial condition for the girders is simply supported under the weight of the cast deck. Each girder is assumed to carry half the weight of the precast deck. After the deck and girders are made composite, the barrier is added to the exterior modules. The barrier dead load is assumed to be evenly distributed between the two modules. Under the additional barrier dead load, the girders are again assumed to be simply supported. During transport, it is assumed that 28-day concrete strength has been reached in the deck and the deck is fully composite with the girders. The self-weight of the module during lifting and placement is assumed as evenly distributed to four pick points (two per girder). The modules are placed such that there is a bearing on each end and are again simply supported. The continuous span configuration, which includes two bearings per pier on either side of the UHPC joints, is analyzed for positive and negative bending and shear (using simple or refined methods). The negative bending moment above the pier is used to find the force couple for continuity design, between the compression plates at the bottom of the girders and the closure joint in the deck. The deck design utilizes the equivalent strip method. 3. DESIGN CRITERIA The first step for any bridge design is to establish the design criteria. The following is a summary of the primary design criteria for this design example: Governing Specifications: AASTHO LRFD Bridge Desing Specifications (5th Edition with 2010 interims) Design Methodology: Load and Resistance Factor Design (LRFD) Live Load Requirements: HL-93 S S3.6 Section Constraints: Wmod.max 200 kipïïºï½ Upper limit on the weight of the modules, based on common lifting and transport capabilities without significantly increasing time and/or cost due to unconventional equipment or permits
127 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 4. MATERIAL PROPERTIES Structural Steel Yield Strength: Fy 50ksiïºï½ STable 6.4.1-1 Structural Steel Tensile Strength: Fu 65ksiïºï½ STable 6.4.1-1 Concrete 28-day Compressive Strength: fc 5ksiïºï½ fc_uhpc 21ksiïºï½ S5.4.2.1 Reinforcement Strength: Fs 60ksiïºï½ S5.4.3 & S6.10.3.7 Steel Density: ws 490pcfïºï½ STable 3.5.1-1 Concrete Density: wc 150pcfïºï½ STable 3.5.1-1 Modulus of Elasticity - Steel: Es 29000ksiïºï½ Modulus of Elasticity - Concrete: Ec 33000 wc 1000pcf ï¦ï§ï¨ ï¶ï·ï¸ 1.5 ï fc ksiïï 4286.8 ksiïï½ïºï½ Modular Ratio: n ceil Es Ec ï¦ï§ï¨ ï¶ï·ï¸ 7ï½ïºï½ Future Wearing Surface Density: Wfws 140pcfïºï½ STable 3.5.1-1 Future Wearing Surface Thickness: tfws 2.5inïºï½ (Assumed) 5. LOAD COMBINATIONS The following load combinations will be used in this design example, in accordance with Table 3.4.1-1. Strength I = 1.25DC + 1.5DW + 1.75(LL+IM), where IM = 33% Strength III = 1.25DC + 1.5DW + 1.40WS Strength V = 1.25DC + 1.5DW + 1.35(LL+IM) + 0.40WS + 1.0WL, where IM = 33% Service I = 1.0DC + 1.0DW + 1.0(LL+IM) + 0.3WS + 1.0WL, where IM = 33% Service II = 1.0DC + 1.0DW + 1.3(LL+IM), where IM = 33% Fatigue I = 1.5(LL+IM), where IM = 15% 6. BEAM SECTION Determine Beam Section Properties: btfx ttfGirder W30x99 Top Flange btf 10.45inïºï½ ttf 0.67inïºï½ Bottom Flange bbf 10.45inïºï½ tbf 0.67inïºï½ Dw x twWeb Dw 28.31inïºï½ tw 0.52inïºï½ Girder Depth dgird 29.7inïºï½ bbfx tbf Check Flange Proportion Requeirements Met: S 6.10.2.2
128 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT btf 2 ttfï 12.0ï£ 1ï½ bbf 2 tbfï 12.0ï£ 1ï½ btf Dw 6 ï³ 1ï½ bbf Dw 6 ï³ 1ï½ ttf 1.1 twïï³ 1ï½ tbf 1.1 twïï³ 1ï½ 0.1 tbf 3 bbfï 12 ttf 3 btfï 12 ï£ 10ï£ 1ï½ tbf bbfï 12 ttf btfï 12 0.3ï³ 1ï½ Properties for use when analyzing under beam self weight (steel only): Atf btf ttfïïºï½ Abf bbf tbfïïºï½ Aw Dw twïïºï½ Asteel Abf Atfï« Awï«ïºï½ Asteel 28.7 in2ïï½ Total steel area. Steel centroid from top. ysteel Atf ttf 2 ï Abf tbf 2 Dwï« ttfï« ï¦ï§ï¨ ï¶ï·ï¸ïï« Aw Dw 2 ttfï« ï¦ï§ï¨ ï¶ï·ï¸ïï« Asteel ïºï½ ysteel 14.8 inïï½ Calculate Iz: Moment of inertia about Z axis. Izsteel tw Dw 3ï 12 btf ttf 3ï 12 ï« bbf tbf 3ï 12 ï« Aw Dw 2 ttfï« ysteelï ï¦ï§ï¨ ï¶ï·ï¸ 2 ïï« Atf ysteel ttf 2 ïï¦ï§ï¨ ï¶ï·ï¸ 2 ïï« Abf Dw tbf 2 ï« ttfï« ysteelï ï¦ï§ï¨ ï¶ï·ï¸ 2 ïï«ïºï½ Calculate Iy: Iysteel Dw tw 3ï ttf btf3ïï« tbf bbf3ïï« 12 ïºï½ Moment of inertia about Y axis. Calculate Ix: Moment of inertia about X axis. Ixsteel 1 3 btf ttf 3ï bbf tbf3ïï« Dw tw3ïï«ï¦ï¨ ï¶ï¸ïïºï½ Izsteel 3923.795 in 4ïï½ Iysteel 127.762 in4ïï½ Ixsteel 3.4 in4ïï½ Asteel 28.7 in2ïï½
129 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Composite Section Properties (Uncracked Section - used for barrier dead load and live load positive bending): Determine composite slab and reinforcing properties Slab thickness assumes some sacrificial thickness; use: tslab 8inïºï½ Dt tslab ttfï« Dwï« tbfï«ï¨ ï© 37.6 inïï½ïºï½ Total section depth beff spacingintïºï½ beff 47 inïï½ Effective width. S 4.6.2.6.1 LRFD Transformed slab width as steel.btr beff n ïºï½ Transformed slab moment of inertia about z axis as steel.Izslab btr tslab 3 12 ïïºï½ Aslab btr tslabïïºï½ Transformed slab area as steel. Slab reinforcement: (Use #5 @ 8" top, and #6 @ 8" bottom; additional bar for continuous segments of #6 @ 12") Typical Cross Section Cross Section Over Support Art 0.465 in2 ft beffï 1.8 in2ïï½ïºï½ Arb 0.66 in2 ft beffï 2.6 in2ïï½ïºï½ Artadd 0.44 in2 ft ï beffï 1.7 in2ïï½ïºï½ Ar Art Arbï« 4.4 in2ïï½ïºï½ Arneg Ar Artaddï« 6.1 in2ïï½ïºï½ crt 2.5in 0.625inï« 5 16 ï¦ï§ï¨ ï¶ï·ï¸inï« 3.4 inïï½ïºï½ crb tslab 1.75inï 6 16 ï¦ï§ï¨ ï¶ï·ï¸inï 5.9 inïï½ïºï½ ref from top of slab cr Art crtï Arb crbïï«ï¨ ï© Ar 4.9 inïï½ïºï½ crneg Art crtï Arb crbïï« Artadd crtïï«ï¨ ï© Arneg 4.5 inïï½ïºï½
130 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Find composite section centroid: Ax Asteel Ar n 1ï( )ï n ï« Aslabï«ïºï½ yslab tslab 2 ïºï½ Centroid of steel from top of slab.yst Atf ttf 2 tslabï« ï¦ï§ï¨ ï¶ï·ï¸ï Abf tbf 2 Dwï« ttfï« tslabï« ï¦ï§ï¨ ï¶ï·ï¸ïï« Aw Dw 2 ttfï« tslabï« ï¦ï§ï¨ ï¶ï·ï¸ïï« Asteel ïºï½ Centroid of transformed composite section from top of slab.yc yst Asteelï cr Arï n 1ï( )ï n ï« Aslab yslabïï« Ax ïºï½ yc 10.3 inïï½ Calculate Transformed Iz for composite section: Transformed moment of inertia about the z axis.Iz Izsteel Asteel yst ycïï¨ ï©2ïï« Izslabï« Aslab yslab ycïï¨ ï©2ïï« Ar n 1ï( )ï n cr ycïï¨ ï©2ïï«ïºï½ Calculate Transformed Iy for composite section: ttr tslab n ïºï½ Transformed slab thickness. Iyslab ttr beff 3ï 12 ïºï½ Transformed moment of inertia about y axis of slab. Transformed moment of inertia about the y axis (ignoring reinforcement). Iy Iysteel Iyslabï«ïºï½ Calculate Transformed Ix for composite section: Transformed moment of inertia about the x axis.Ix 1 3 btf ttf 3ï bbf tbf3ïï« Dw tw3ïï« btr tslab3ïï«ï¦ï¨ ï¶ï¸ïïºï½ Results: Ax 86.2 in 2ïï½ Iy 10015.7 in4ïï½ Iz 10959.8 in4ïï½ Ix 1149.3 in4ïï½ Composite Section Properties (Uncracked Section - used for live load negative bending): Find composite section area and centroid: Axneg Asteel Arneg n 1ï( )ï n ï« Aslabï«ïºï½ Centroid of transformed composite section from top of slab.ycneg ysteel Asteelï crneg Arnegï n 1ï( )ï n ï« Aslab yslabïï« Axneg ïºï½ ycneg 7.6 inïï½ Calculate Transformed Izneg for composite negative moment section: Transformed moment of inertia about the z axis. Izneg Izsteel Asteel ysteel ycnegïï¨ ï©2ïï« Izslabï« Aslab yslab ycnegïï¨ ï©2ïï« Arneg n 1ï( )ïn crneg ycnegïï¨ ï© 2ïï«ïºï½ Izneg 6457.4 in 4ïï½
131 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Composite Section Properties (Cracked Section - used for live load negative bending): Find cracked section area and centroid: Acr Asteel Arnegï« 34.9 in2ïï½ïºï½ ycr Asteel ysteelï Arneg crnegïï«ï¨ ï© Acr 13 inïï½ïºï½ ycrb tslab ttfï« Dwï« tbfï« ycrï 24.6 inïï½ïºï½ Find cracked section moments of inertia and section moduli: Izcr Izsteel Asteel ysteel ycrïï¨ ï©2ïï« Ar cr ycrïï¨ ï©2ïï«ïºï½ Izcr 4310.8 in4ïï½ Iycr Iysteelïºï½ Iycr 127.8 in4ïï½ Ixcr 1 3 btf ttf 3ï bbf ttf3ïï« Dw tw3ïï«ï¦ï¨ ï¶ï¸ïïºï½ Ixcr 3.4 in4ïï½ dtopcr ycr crtïïºï½ dtopcr 9.6 inïï½ dbotcr tslab ttfï« Dwï« tbfï« ycrïïºï½ dbotcr 24.6 inïï½ Stopcr Izcr dtopcr ïºï½ Stopcr 450.7 in3ïï½ Sbotcr Izcr dbotcr ïºï½ Sbotcr 174.9 in3ïï½ 7. PERMANENT LOADS Phase 1: Steel girders are simply supported, and support their self-weight plus the weight of the slab. Steel girders in each module for this example are separated by three diaphragms - one at each bearing location, and one at midspan. Other module span configurations may require an increase or decrease in the number of diaphragms. Wdeck_int wc spacingintï tdïïºï½ Wdeck_int 514.1 plfïï½ Wdeck_ext wc spacingextï tdïïºï½ Wdeck_ext 525 plfïï½ Whaunch wc whï thïïºï½ Whaunch 21.9 plfïï½ Wstringer ws1ïºï½ Wstringer 99 plfïï½ Diaphragms: MC18x42.7 Thickness Conn. Plate tconn 5 8 inïºï½ Diaphragm Weight ws2 42.7plfïºï½ Width Conn. Plate wconn 5inïºï½ Diaphragm Length Ldiaph 4ft 2.5inï«ïºï½ Height Conn. Plate hconn 28.5inïºï½ Wdiaphragm ws2 Ldiaph 2 ïïºï½ Wdiaphragm 89.8 lbfïï½ Wconn 2 wsï tconnï wconnï hconnïïºï½ Wconn 50.5 lbfïï½ WDCpoint Wdiaphragm Wconnï«ï¨ ï© 1.05ïïºï½ WDCpoint 147.4 lbfïï½ Equivalent distributed load from DC point loads: wDCpt_equiv 3 WDCpointï Lstr 6.4 plfïï½ïºï½ Interior Uniform Dead Load, Phase 1: WDCuniform1_int Wdeck_int Whaunchï« Wstringerï« wDCpt_equivï« 641.3 plfïï½ïºï½ Exterior Uniform Dead Load, Phase 1: WDCuniform1_ext Wdeck_ext Whaunchï« Wstringerï« wDCpt_equivï« 652.2 plfïï½ïºï½
132 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Moments due to Phase 1 DL: MDC1_int x( ) WDCuniform1_int xï 2 Lstr xïï¨ ï©ïïºï½ MDC1_ext x( ) WDCuniform1_ext xï2 Lstr xïï¨ ï©ïïºï½ Shear due to Phase 1 DL: VDC1_int x( ) WDCuniform1_int Lstr 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ VDC1_ext x( ) WDCuniform1_ext Lstr 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Phase 2: Steel girders are simply supported and composite with the deck slab, and support their self-weight plus the weight of the slab in addition to barriers on exterior modules. Barriers are assumed to be evenly distributed between the two exterior module girders. Barrier Area Abarrier 2.89ft 2ïºï½ Barrier Weight Wbarrier wc Abarrierïï¨ ï© 2 ïºï½ Wbarrier 216.8 plfïï½ Interior Dead Load, Phase 2: WDCuniform_int WDCuniform1_int 641.3 plfïï½ïºï½ Exterior Dead Load, Phase 2: WDCuniform_ext WDCuniform1_ext Wbarrierï« 869 plfïï½ïºï½ Moments due to Phase 2 DL: MDC2_int x( ) WDCuniform_int xï 2 Lstr xïï¨ ï©ïïºï½ MDC2_ext x( ) WDCuniform_ext xï2 Lstr xïï¨ ï©ïïºï½ Shear due to Phase 2 DL: VDC2_int x( ) WDCuniform_int Lstr 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ VDC2_ext x( ) WDCuniform_ext Lstr 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Phase 3: Girders are composite and have been made continuous. Utilities and future wearing surface are applied. Unit Weight Overlay wws 30psfïºï½ Wws_int wws spacingintïïºï½ Wws_int 117.5 plfïï½ Wws_ext wws spacingext 1 ftïï 7inïï¨ ï©ïïºï½ Wws_ext 72.5 plfïï½ Unit Weight Utilities Wu 15plfïºï½ WDWuniform_int Wws_int Wuï«ïºï½ WDWuniform_int 132.5 plfïï½ WDWuniform_ext Wws_ext Wuï«ïºï½ WDWuniform_ext 87.5 plfïï½ Moments due to DW: MDW_int x( ) WDWuniform_int xï 2 Lstr xïï¨ ï©ïïºï½ MDW_ext x( ) WDWuniform_ext xï2 Lstr xïï¨ ï©ïïºï½ Shears due to DW: VDW_int x( ) WDWuniform_int Lstr 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ VDW_ext x( ) WDWuniform_ext Lstr 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½
133 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 8. PRECAST LIFTING WEIGHTS AND FORCES This section addresses the construction loads for lifting the module into place. The module is lifted from four points, at some distance, Dlift from each end of each girder. Distance from end of lifting point: Dlift 8.75ftïºï½ Assume weight uniformly distributed along girder, with 30% Dynamic Dead Load Allowance: Dynamic Dead Load Allowance: DLIM 30%ïºï½ Interior Module: Total Interior Module Weight: Wint Lstr WDCuniform_intï 3 WDCpointïï«ï¨ ï© 2ï 1 DLIMï«( )ï 117 kipïï½ïºï½ Vertical force at lifting point: Flift_int Wint 4 29.3 kipïï½ïºï½ Equivalent distributed load: wint_IM Wint 2 Lstrïï¨ ï© 842 plfïï½ïºï½ Min (Neg.) Moment during lifting: Mlift_neg_max_int wint_IMï Dlift 2ï¦ï¨ ï¶ï¸ 2 ïïºï½ Mlift_neg_max_int 32.2ï kip ftïïï½ Max (Pos.) Moment during lifting: Mlift_pos_max_int 0 wint_IM Lstr 2 Dliftïïï¨ ï©2ï 8 Mlift_neg_max_intï« 0ï¼if wint_IM Lstr 2 Dliftïïï¨ ï©2ï 8 Mlift_neg_max_intï« ïºï½ Mlift_pos_max_int 252.4 kip ftïïï½ Exterior Module: Total Exterior Module Weight: Wext Lstr WDCuniform_extï 3 WDCpointïï« Wbarrier Lstrïï«ï¨ ï© 2ï 1 DLIMï«( )ï 197.3 kipïï½ïºï½ Vertical force at lifting point: Flift_ext Wext 4 49.3 kipïï½ïºï½ Equivalent distributed load: wext_IM Wext 2 Lstrï 1419.7 plfïï½ïºï½ Min (Neg.) Moment during lifting: Mlift_neg_max_ext wext_IMï Dlift 2 2 ïïºï½ Mlift_neg_max_ext 54.3ï kip ftïïï½ Max (Pos.) Moment during lifting: Mlift_pos_max_ext 0 wext_IM Lstr 2 Dliftïïï¨ ï©2ï 8 Mlift_neg_max_extï« 0ï¼if wext_IM Lstr 2 Dliftïïï¨ ï©2ï 8 Mlift_neg_max_extï« ïºï½ Mlift_pos_max_ext 425.5 kip ftïïï½ Max Shear during lifting: Vlift max wext_IM Dliftï Flift_ext wext_IM Dliftïïï¬ï ï¨ ï© 36.9 kipïï½ïºï½
134 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 9. LIVE LOAD DISTRIBUTION FACTORS These factors represent the distribution of live load from the deck to the girders in accordance with AASHTO Section 4, and assumes the deck is fully continuous across the joints. Girder Section Modulus: Izsteel 3923.8 in 4ïï½ Girder Area: Asteel 28.7 in 2ïï½ Girder Depth: dgird 29.7 inïï½ Distance between centroid of deck and centroid of beam: eg td 2 thï« dgird 2 ï« 22.1 inïï½ïºï½ Modular Ratio: n 7ï½ Multiple Presence Factors: MP1 1.2ïºï½ MP2 1.0ïºï½ S3.6.1.1.2-1 Interior Stringers for Moment: S4.6.2.2.1-1 One Lane Loaded: Kg n Izsteel Asteel eg 2ïï«ï¦ï¨ ï¶ï¸ï 125670.9 in4ïï½ïºï½ gint_1m 0.06 spacingint 14ft ï¦ï§ï¨ ï¶ï·ï¸ 0.4 spacingint Lspan ï¦ï§ï¨ ï¶ï·ï¸ 0.3 ï Kg Lspan td 3ï ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ 0.1 ïï« ï©ïª ïªï« ï¹ïº ïºï» 0.269ï½ïºï½ Two Lanes Loaded: gint_2m 0.075 spacingint 9.5ft ï¦ï§ï¨ ï¶ï·ï¸ 0.6 spacingint Lspan ï¦ï§ï¨ ï¶ï·ï¸ 0.2 ï Kg Lspan td 3ï ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ 0.1 ïï« ï©ïª ïªï« ï¹ïº ïºï» 0.347ï½ïºï½ Governing Factor: gint_m max gint_1m gint_2mï¬ï ï¨ ï© 0.347ï½ïºï½ Interior Stringers for Shear: One Lane Loaded: gint_1v 0.36 spacingint 25ft ï«ï¦ï§ï¨ ï¶ï·ï¸ 0.517ï½ïºï½ Two Lanes Loaded: gint_2v 0.2 spacingint 12ft ï« spacingint 35ft ï¦ï§ï¨ ï¶ï·ï¸ 2 ïï« ï©ïª ï« ï¹ïº ï» 0.514ï½ïºï½ Governing Factor: gint_v max gint_1v gint_2vï¬ï ï¨ ï© 0.517ï½ïºï½ Exterior Stringers for Moment: One Lane Loaded: Use Lever Rule. Wheel is 2' from barrier; barrier is 2" beyond exterior stringer. de 2inïºï½ Lspa 4.5ftïºï½ r Lspa deï« 2ftï 2.7 ftïï½ïºï½ gext_1m MP1 0.5r Lspa ï 0.356ï½ïºï½ Two Lanes Loaded: e2m 0.77 de 9.1ft ï« 0.7883ï½ïºï½ gext_2m e2m gint_2mï 0.273ï½ïºï½ Governing Factor: gext_m max gext_1m gext_2mï¬ï ï¨ ï© 0.356ï½ïºï½ Exterior Stringers for Shear: One Lane Loaded: Use Lever Rule. gext_1v gext_1m 0.356ï½ïºï½
135 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Two Lanes Loaded: e2v 0.6 de 10ft ï« 0.62ï½ïºï½ gext_2v e2v gint_2vï 0.317ï½ïºï½ Governing Factor: gext_v max gext_1v gext_2vï¬ï ï¨ ï© 0.356ï½ïºï½ FACTOR TO USE FOR SHEAR: gv max gint_v gext_vï¬ï ï¨ ï© 0.517ï½ïºï½ FACTOR TO USE FOR MOMENT: gm max gint_m gext_mï¬ï ï¨ ï© 0.356ï½ïºï½ 10. LOAD RESULTS Case 1: Dead Load on Steel Only (calculated in Section 7). Negative moments are zero and are not considered. Because the girder is simply supported, the maximum moment is at x = Lstr/2 and the maximum shear is at x = 0. Interior Girder MDC1int MDC1_int Lstr 2 ï¦ï§ï¨ ï¶ï·ï¸ 387.2 kip ftïïï½ïºï½ MDW1int 0 kipï ftïïºï½ MLL1int 0kip ftïïºï½ VDC1int VDC1_int 0( ) 22.3 kipïï½ïºï½ VDW1int 0 kipïïºï½ VLL1int 0 kipïïºï½ Exterior Girder MDC1ext MDC1_ext Lstr 2 ï¦ï§ï¨ ï¶ï·ï¸ 393.8 kip ftïïï½ïºï½ MDW1ext 0 kipï ftïïºï½ MLL1ext 0 kipï ftïïºï½ VDC1ext VDC1_ext 0( ) 22.7 kipïï½ïºï½ VDW1ext 0 kipïïºï½ VLL1ext 0 kipï ftïïºï½ Load Cases: M1_STR_I max 1.25 MDC1intï 1.5 MDW1intïï« 1.75 MLL1intïï« 1.25 MDC1extï 1.5 MDW1extïï« 1.75 MLL1extïï«ï¬ï ï¨ ï© 492.3 kip ftïïï½ïºï½ V1_STR_I max 1.25 VDC1intï 1.5 VDW1intïï« 1.75 VLL1intïï« 1.25 VDC1extï 1.5 VDW1extïï« 1.75 VLL1extïï«ï¬ï ï¨ ï© 28.3 kipïï½ïºï½ Case 2: Dead Load on Composite Section (calculated in Section 7). Negative moments are zero and are not considered. Again, the maximum moment occur at x = Lstr/2 and the maximum shear is at x = 0. Interior Girder MDC2int MDC2_int Lstr 2 ï¦ï§ï¨ ï¶ï·ï¸ 387.2 kip ftïïï½ïºï½ MDW2int 0 kipï ftïïºï½ MLL2int 0 kipï ftïïºï½ VDC2int VDC2_int 0( ) 22.3 kipïï½ïºï½ VDW2int 0 kipïïºï½ VLL2int 0 kipïïºï½ Exterior Girder MDC2ext MDC2_ext Lstr 2 ï¦ï§ï¨ ï¶ï·ï¸ 524.7 kip ftïïï½ïºï½ MDW2ext 0 kipï ftïïºï½ MLL2ext 0 kipï ftïïºï½ VDC2ext VDC2_ext 0( ) 30.2 kipïï½ïºï½ VDW2ext 0 kipïïºï½ VLL2ext 0 kipïïºï½ Load Cases: M2_STR_I max 1.25 MDC2intï 1.5 MDW2intïï« 1.75 MLL2intïï« 1.25 MDC2extï 1.5 MDW2extïï« 1.75 MLL2extïï«ï¬ï ï¨ ï© 655.8 kip ftïïï½ïºï½ V2_STR_I max 1.25 VDC2intï 1.5 VDW2intïï« 1.75 VLL2intïï« 1.25 VDC2extï 1.5 VDW2extïï« 1.75 VLL2extïï«ï¬ï ï¨ ï© 37.7 kipïï½ïºï½ Case 3: Composite girders are lifted into place from lifting points located distance Dlift from the girder edges. Maximum moments and shears were calculated in Section 8. Interior Girder MDC3int Mlift_pos_max_int 252.4 kip ftïïï½ïºï½ MDW3int 0 kipï ftïïºï½ MLL3int 0 kipï ftïïºï½ MDC3int_neg Mlift_neg_max_int 32.2 kip ftïïï½ïºï½ MDW3int_neg 0 kipï ftïïºï½ MLL3int_neg 0 kipï ftïïºï½ VDC3int Vlift 36.9 kipïï½ïºï½ VDW3int 0 kipïïºï½ VLL3int 0 kipïïºï½ Exterior Girder MDC3ext Mlift_pos_max_ext 425.5 kip ftïïï½ïºï½ MDW3ext 0 kipï ftïïºï½ MLL3ext 0 kipï ftïïºï½ MDC3ext_neg Mlift_neg_max_ext 54.3 kip ftïïï½ïºï½ MDW3ext_neg 0 kipï ftïïºï½ MLL3ext_neg 0 kipï ftïïºï½ VDC3ext Vlift 36.9 kipïï½ïºï½ VDW3ext 0 kipïïºï½ VLL3ext 0 kipïïºï½ Load Cases: M3_STR_I max 1.5 MDC3intï 1.5 MDW3intïï« 1.5 MDC3extï 1.5 MDW3extïï«ï¬ï ï¨ ï© 638.3 kip ftïïï½ïºï½ M3_STR_I_neg max 1.5 MDC3int_negï 1.5 MDW3int_negïï« 1.5 MDC3ext_negï 1.5 MDW3ext_negïï«ï¬ï ï¨ ï© 81.5 kip ftïïï½ïºï½
136 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT V3_STR_I max 1.5 VDC3intï 1.5 VDW3intïï« 1.5 VDC3extï 1.5 VDW3extïï«ï¬ï ï¨ ï© 55.4 kipïï½ïºï½ Case 4: Composite girders made continuous. Utilities and future wearing surface are applied, and live load. Maximum moment and shear results are from a finite element analysis not included in this design example. The live load value includes the lane fraction calculated in Section 9, and impact. Governing Loads: MDC4 440 kipï ftïïºï½ MDW4 43.3 kipï ftïïºï½ MLL4 590.3 kipï ftïïºï½ MWS4 0kip ftïïºï½ MW4 0kip ftïïºï½ MDC4neg 328.9ï kipï ftïïºï½ MDW4neg 32.3ï kipï ftïïºï½ MLL4neg 314.4ï kip ftïïºï½ MWS4neg 0 kipï ftïïºï½ MWL4neg 0 kipï ftïïºï½ Vu 145.3kipïºï½ Load Cases: M4_STR_I 1.25 MDC4ï 1.5 MDW4ïï« 1.75 MLL4ïï« 1648 kip ftïïï½ïºï½ M4_STR_I_neg 1.25 MDC4negï 1.5 MDW4negïï« 1.75 MLL4negïï« 1009.8ï kip ftïïï½ïºï½ M4_STR_III 1.25 MDC4ï 1.5 MDW4ïï« 1.4 MWS4ïï« 614.9 kip ftïïï½ïºï½ M4_STR_III_neg 1.25 MDC4negï 1.5 MDW4negïï« 1.4 MWS4ïï« 459.6ï kip ftïïï½ïºï½ M4_STR_V 1.25 MDC4ï 1.5 MDW4ïï« 1.35 MLL4ïï« 0.4 MWS4ïï« 1.0 MW4ïï« 1411.9 kip ftïïï½ïºï½ M4_STR_V_neg 1.25 MDC4negï 1.5 MDW4negïï« 1.35 MLL4negïï« 0.4 MWS4negïï« 1.0 MWL4negïï« 884ï kip ftïïï½ïºï½ M4_SRV_I 1.0 MDC4ï 1.0 MDW4ïï« 1.0 MLL4ïï« 0.3 MWS4ïï« 1.0 MW4ïï« 1073.6 kip ftïïï½ïºï½ M4_SRV_I_neg 1.0 MDC4negï 1.0 MDW4negïï« 1.0 MLL4negïï« 0.3 MWS4negïï« 1.0 MWL4negïï« 675.6ï kip ftïïï½ïºï½ M4_SRV_II 1.0 MDC4ï 1.0 MDW4ïï« 1.3 MLL4ïï« 1250.7 kip ftïïï½ïºï½ M4_SRV_II_neg 1.0 MDC4negï 1.0 MDW4negïï« 1.3 MLL4negïï« 769.9ï kip ftïïï½ïºï½
137 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 11. FLEXURAL STRENGTH The flexural resistance shall be determined as specified in LRFD Design Article 6.10.6.2. Determine Stringer Plastic Moment Capacity First. LFRD Appendix D6 Plastic Moment Find location of PNA: Forces: Prt Art Fsï 109.3 kipïï½ïºï½ Ps 0.85 fcï beffï tslabï 1598 kipïï½ïºï½ Pw Fy Dwï twï 736.1 kipïï½ïºï½ Prb Arb Fsï 155.1 kipïï½ïºï½ Pc Fy btfï ttfï 350.1 kipïï½ïºï½ Pt Fy bbfï tbfï 350.1 kipïï½ïºï½ PNApos "case 1" Pt Pwï«ï¨ ï© Pc Psï« Prtï« Prbï«ï¨ ï©ï³if "case 2" Pt Pwï« Pcï«ï¨ ï© Ps Prtï« Prbï«ï¨ ï©ï³ï©ï« ï¹ï»if "case 3" Pt Pwï« Pcï«ï¨ ï© crbtslab Psï Prtï« Prbï« ï¦ï§ï¨ ï¶ï·ï¸ ï³ï©ïªï« ï¹ïºï» if "case 4" Pt Pwï« Pcï« Prbï«ï¨ ï© crbtslab Psï Prtï« ï¦ï§ï¨ ï¶ï·ï¸ ï³ï©ïªï« ï¹ïºï» if "case 5" Pt Pwï« Pcï« Prbï«ï¨ ï© crttslab Psï Prtï« ï¦ï§ï¨ ï¶ï·ï¸ ï³ï©ïªï« ï¹ïºï» if "case 6" Pt Pwï« Pcï« Prbï« Prtï«ï¨ ï© crttslab Psï ï¦ï§ï¨ ï¶ï·ï¸ ï³if "case 7" Pt Pwï« Pcï« Prbï« Prtï«ï¨ ï© crttslab Psï ï¦ï§ï¨ ï¶ï·ï¸ ï£if otherwise otherwise otherwise otherwise otherwise otherwise ïºï½ PNApos "case 4"ï½ PNAneg "case 1" Pc Pwï«ï¨ ï© Pt Prtï« Prbï«ï¨ ï©ï³if "case 2" Pt Pwï« Pcï«ï¨ ï© Prt Prbï«ï¨ ï©ï³ï©ï« ï¹ï»if otherwise ïºï½ PNAneg "case 1"ï½ Calculate Y, Dp, and Mp: D Dwïºï½ ts tslabïºï½ th 0ïºï½ Crt crtïºï½ Crb crbïºï½ Case I : Plastic Nuetral Axis in the Steel Web Y1 D 2 Pt Pcï Psï Prtï Prbï Pw 1ï«ï¦ï§ï¨ ï¶ï·ï¸ ïïºï½ DP1 ts thï« ttfï« Y1ï«ïºï½
138 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT MP1 Pw 2D Y1 2 D Y1ïï¨ ï©2ï«ï©ï« ï¹ï»ï Ps Y1 ts2ï« ttfï« thï« ï¦ï§ï¨ ï¶ï·ï¸ï Prt ts Crtï ttfï« Y1ï« thï«ï¨ ï©ïï« Prb ts Crbï ttfï« Y1ï« thï«ï¨ ï©ïï« Pc Y1 ttf 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ï Pt D Y1ï tbf 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïï«ï« ï®ï®ï®ï©ïª ïª ïª ï« ï¹ïº ïº ïº ï» ï«ïºï½ Y1neg D 2 ï¦ï§ï¨ ï¶ï·ï¸ 1 Pc Ptï Prtï Prbïï¨ ï© Pw ï«ï©ïªï« ï¹ïºï» ïïºï½ Dp1neg ts thï« ttfï« Y1negï«ïºï½ DCP1neg D 2 Pwï ï¦ï§ï¨ ï¶ï·ï¸ Pt Pwï« Prbï« Prtï« Pcïï¨ ï©ïïºï½ Mp1neg Pw 2 Dï ï¦ï§ï¨ ï¶ï·ï¸ Y1neg 2 Dw Y1negïï¨ ï©2ï«ï©ï« ï¹ï»ï Prt ts Crtï ttfï« Y1negï« thï«ï¨ ï©ïï« Prb ts Crbï ttfï« Y1negï« thï«ï¨ ï©ïï« Pt D Y1negï tbf 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ï Pc Y1neg ttf 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïï«ï« ï®ï®ï®ï©ïª ïª ïª ï« ï¹ïº ïº ïº ï» ïºï½ Case II: Plastic Nuetral Axis in the Steel Top Flange Y2 ttf 2 Pw Ptï« Psï Prtï Prbï Pc 1ï«ï¦ï§ï¨ ï¶ï·ï¸ ïïºï½ DP2 ts thï« Y2ï«ïºï½ MP2 Pc 2ttf Y2 2 ttf Y2ïï¨ ï©2ï«ï©ï« ï¹ï»ï Ps Y2 ts2ï« thï« ï¦ï§ï¨ ï¶ï·ï¸ï Prt ts Crtï thï« Y2ï«ï¨ ï©ïï« Prb ts Crbï thï« Y2ï«ï¨ ï©ïï« Pw D 2 ttfï« Y2ïï¦ï§ï¨ ï¶ï·ï¸ï Pt D Y2ï tbf 2 ï« ttfï« ï¦ï§ï¨ ï¶ï·ï¸ïï«ï« ï®ï®ï®ï©ïª ïª ïª ï« ï¹ïº ïº ïº ï» ï«ïºï½ Y2neg ttf 2 ï¦ï§ï¨ ï¶ï·ï¸ 1 Pw Pcï« Prtï Prbïï¨ ï© Pt ï«ï©ïªï« ï¹ïºï» ïïºï½ DP2neg ts thï« Y2negï«ïºï½ DCP2neg Dïºï½ Mp2neg Pt 2 ttfï ï¦ï§ï¨ ï¶ï·ï¸ Y2neg 2 ttf Y2negïï¨ ï©2ï«ï©ï« ï¹ï»ï Prt ts Crtï thï« Y2negï«ï¨ ï©ï Prb ts Crbï thï« Y2negï«ï¨ ï©ïï« Pw ttf Y2negï D 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ï Pc ts thï« Y2negï ttf 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïï«ï« ï®ï®ï®ï©ïª ïªï« ï¹ïº ïºï» ï«ïºï½ Case III: Plastic Nuetral Axis in the Concrete Deck Below the Bottom Reinforcing Y3 ts Pc Pwï« Ptï« Prtï Prbï Ps ï¦ï§ï¨ ï¶ï·ï¸ ïïºï½ DP3 Y3ïºï½ MP3 Ps 2ts Y3 2ï¦ï¨ ï¶ï¸ï Prt Y3 Crtïï¨ ï©ï Prb Crb Y3ïï¨ ï©ïï« Pc ttf2 tsï« thï« Y3ï ï¦ï§ï¨ ï¶ï·ï¸ïï« Pw D 2 ttfï« thï« tsï« Y3ïï¦ï§ï¨ ï¶ï·ï¸ïï« Pt D tbf 2 ï« ttfï« tsï« thï« Y3ï ï¦ï§ï¨ ï¶ï·ï¸ïï« ï®ï®ï®ï©ïª ïª ïª ï« ï¹ïº ïº ïº ï» ï«ïºï½ Case IV: Plastic Nuetral Axis in the Concrete Deck in the bottom reinforcing layer Y4 Crbïºï½ DP4 Y4ïºï½ MP4 Ps 2ts Y4 2ï¦ï¨ ï¶ï¸ï Prt Y4 Crtïï¨ ï©ï Pc ttf2 thï« tsï« Y4ï ï¦ï§ï¨ ï¶ï·ï¸ïï« Pw D 2 ttfï« thï« tsï« Y4ïï¦ï§ï¨ ï¶ï·ï¸ïï« Pt D tbf 2 ï« ttfï« thï« tsï« Y4ï ï¦ï§ï¨ ï¶ï·ï¸ïï« ï®ï®ï®ï©ïª ïª ïª ï« ï¹ïº ïº ïº ï» ï«ïºï½
139 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Case V: Plastic Nuetral Axis in the Concrete Deck between top and bot reinforcing layers Y5 ts Prb Pcï« Pwï« Ptï« Prtï Ps ï¦ï§ï¨ ï¶ï·ï¸ ïïºï½ DP5 Y5ïºï½ MP5 Ps 2ts Y5 2ï¦ï¨ ï¶ï¸ï Prt Y5 Crtïï¨ ï©ï Prb ts Crbïï¨ ï© Y5ïï©ï« ï¹ï»ïï« Pc ttf2 tsï« thï« Y5ï ï¦ï§ï¨ ï¶ï·ï¸ïï« Pw D 2 ttfï« thï« tsï« Y5ïï¦ï§ï¨ ï¶ï·ï¸ïï« Pt D tbf 2 ï« ttfï« tsï« thï« Y5ï ï¦ï§ï¨ ï¶ï·ï¸ïï« ï®ï®ï®ï©ïª ïª ïª ï« ï¹ïº ïº ïº ï» ï«ïºï½ Ypos Y1 PNApos "case 1"=if Y2 PNApos "case 2"=if Y3 PNApos "case 3"=if Y4 PNApos "case 4"=if Y5 PNApos "case 5"=if ïºï½ DPpos DP1 PNApos "case 1"=if DP2 PNApos "case 2"=if DP3 PNApos "case 3"=if DP4 PNApos "case 4"=if DP5 PNApos "case 5"=if ïºï½ MPpos MP1 PNApos "case 1"=if MP2 PNApos "case 2"=if MP3 PNApos "case 3"=if MP4 PNApos "case 4"=if MP5 PNApos "case 5"=if ïºï½ Ypos 5.9 inïï½ DPpos 5.9 inïï½ MPpos 2338.1 kip ftïïï½ Dp = distance from the top of slab of composite section to the neutral axis at the plastic moment (neglect positive moment reinforcement in the slab). Yneg Y1neg PNAneg "case 1"=if Y2neg PNAneg "case 2"=if ïºï½ DPneg Dp1neg PNAneg "case 1"=if DP2neg PNAneg "case 2"=if ïºï½ MPneg Mp1neg PNAneg "case 1"=if Mp2neg PNAneg "case 2"=if ïºï½ Yneg 9.1 inïï½ DPneg 17.7 inïï½ MPneg 19430.1 kip inïïï½ Depth of web in compression at the plastic moment [D6.3.2]: At bbf tbfïïºï½ Ac btf ttfïïºï½ Dcppos D 2 Fy Atï Fy Acïï 0.85 fcï Aslabïï Fs Arïï Fy Awï 1ï«ï¦ï§ï¨ ï¶ï·ï¸ ïºï½ Dcppos 0in( ) PNApos "case 1"ï¹if 0in( ) Dcppos 0ï¼ï¨ ï©if Dcppos PNApos "case 1"=if ïºï½ Dcpneg DCP1neg PNAneg "case 1"=if DCP2neg PNAneg "case 2"=if ïºï½ Dcpneg 19.2 inïï½ Dcppos 0 inïï½ Positive Flexural Compression Check: From LRFD Article 6.10.2 Check for compactness: Web Proportions: Web slenderness Limit: Dw tw 150ï£ 1ï½ 2 Dcppos tw ï 3.76 Es Fy ïï£ 1ï½ S 6.10.6.2.2 Therefore Section is considered compact and shall satisfy the requirements of Article 6.10.7.1. Mn MPpos DPpos 0.1 Dtïï£if MPpos 1.07 0.7 DPpos Dt ïïï¦ï§ï¨ ï¶ï·ï¸ ï otherwise ïºï½ Mn 2246.4 kip ftïïï½
140 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Negative Moment Capacity Check (Appendix A6): Web Slenderness: Dt 37.6 inïï½ Dcneg Dt ycrï tbfï 24 inïï½ïºï½ 2 Dcnegï tw 5.7 Es Fy ïï¼ 1ï½ S Appendix A6 (for skew less than 20 deg). Moment ignoring concrete: Myt Fy Sbotcrï 8745.1 kip inïïï½ïºï½ Myc Fs Stopcrï 27039.2 kip inïïï½ïºï½ My min Myc Mytï¬ï ï¨ ï© 8745.1 kip inïïï½ïºï½ Web Compactness: Check for Permanent Deformations (6.10.4.2): Dn max tslab ttfï« Dwï« ycï yc tslabï ttfïï¬ï ï¨ ï© 26.7 inïï½ïºï½ Gov if yc tslabï ttfï yc crtïï¬ï Dnï¬ï ï¨ ï© 6.9 inïï½ïºï½ fn M4_SRV_II_neg Gov Iz ï 5.8 ksiïï½ïºï½ Steel stress on side of Dn Ï min 1.0 Fy fn ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 1ï½ïºï½ β 2 Dnï tw Atf ï 4ï½ïºï½ Rh 12 β 3Ï Ï3ïï¨ ï©ïï«ï©ï« ï¹ï» 12 2 βïï«( ) 1ï½ïºï½ λrw 5.7 Es Fy ïïºï½ λPWdcp min λrw Dcpneg Dcneg ï Es Fy 0.54 MPneg Rh Myï ï 0.09ïï¦ï§ï¨ ï¶ï·ï¸ 2 ï¬ï ï©ïª ïª ïª ïª ïªï« ï¹ïº ïº ïº ïº ïºï» 19.6ï½ïºï½ 2 Dcpneg tw ï λPWdcpï£ 0ï½ Web Plastification: Rpc MPneg Myc 0.7ï½ïºï½ Rpt MPneg Myt 2.2ï½ïºï½ Flexure Factor: Ïf 1.0ïºï½ Tensile Limit: Mr_neg_t Ïf Rptï Mytï 1619.2 kip ftïïï½ïºï½ Compressive Limit: Local Buckling Resistance: λf bbf 2 tbfï 7.8ï½ïºï½ λrf 0.95 0.76 Es Fy ïï 19.9ï½ïºï½ λpf 0.38 Es Fy ï 9.2ï½ïºï½ Fyresid max min 0.7 Fyï Rh Fyï Stopcr Sbotcr ïï¬ï Fyï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 0.5 Fyïï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 35.0 ksiïï½ïºï½ MncLB Rpc Mycïï¨ ï© Î»f λpfï£if Rpc Mycï 1 1 Fyresid Stopcrï Rpc Mycï ïï¦ï§ï¨ ï¶ï·ï¸ λf λpfï λrf λpfï ï¦ï§ï¨ ï¶ï·ï¸ ïï©ïªï« ï¹ïºï» ïï©ïªï« ï¹ïºï» otherwise ïºï½ MncLB 1619.2 kip ftïïï½
141 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Lateral Torsional Buckling Resistance: Lb Lstrï¨ ï© 2 3ï 11.6 ftïï½ïºï½ Inflection point assumed to be at 1/6 span rt bbf 12 1 1 3 Dcneg twï bbf tbfï ïï«ï¦ï§ï¨ ï¶ï·ï¸ ï 2.4 inïï½ïºï½ Lp 1.0 rtï Es Fy ï 57.6 inïï½ïºï½ h D tbfï« 29 inïï½ïºï½ Cb 1.0ïºï½ Jb D tw 3ï 3 bbf tbf 3ï 3 1 0.63 tbf bbf ïïï¦ï§ï¨ ï¶ï·ï¸ ïï« btf ttf 3ï 3 1 0.63 ttf btf ïïï¦ï§ï¨ ï¶ï·ï¸ ïï« 3.3 in4ïï½ïºï½ Lr 1.95 rtï Es Fyresid ï Jb Sbotcr hï ï 1 1 6.76 Fyresid Es Sbotcr hï Jb ïï¦ï§ï¨ ï¶ï·ï¸ 2 ïï«ï«ï 240 inïï½ïºï½ Fcr Cb Ï2ï Esï Lb rt ï¦ï§ï¨ ï¶ï·ï¸ 2 1 0.078 Jb Sbotcr hï ï Lb rt ï¦ï§ï¨ ï¶ï·ï¸ 2 ïï«ï 91.7 ksiïï½ïºï½ MncLTB Rpc Mycïï¨ ï© Lb Lpï£if min Cb 1 1 Fyresid Sbotcrï Rpc Mycï ïï¦ï§ï¨ ï¶ï·ï¸ Lb Lpïï¨ ï© Lr Lpïï¨ ï©ïï ï©ïªï« ï¹ïºï» ï Rpcï Mycï Rpc Mycïï¬ï ï©ïªï« ï¹ïºï» Lp Lbï¼ Lrï£if min Fcr Sbotcrï Rpc Mycïï¬ï ï¨ ï© Lb Lrï¾if ïºï½ MncLTB 1124.2 kip ftïïï½ Mr_neg_c Ïf min MncLB MncLTBï¬ï ï¨ ï©ï 1124.2 kip ftïïï½ïºï½ Governing negative moment capacity: Mr_neg min Mr_neg_t Mr_neg_cï¬ï ï¨ ï© 1124.2 kip ftïïï½ïºï½ 12. FLEXURAL STRENGTH CHECKS Phase 1: First, check the stress due to the dead load on the steel section only. (LRFD 6.10.3 - Constructability Requirements Reduction factor for construction Ïconst 0.9ïºï½ Load Combination for construction 1.25 MDCï Max Moment applied, Phase 1: (at midspan) Mint_P1 1.25 MDC1_int Lstr 2 ï¦ï§ï¨ ï¶ï·ï¸ 484 kip ftïïï½ïºï½ Interior( ) Mext_P1 1.25 MDC1_ext Lstr 2 ï¦ï§ï¨ ï¶ï·ï¸ 492.3 kip ftïïï½ïºï½ Exterior( ) Maximum Stress, Phase 1: fint_P1 Mint_P1 ysteelï Izsteel 21.9 ksiïï½ïºï½ Interior( ) fext_P1 Mext_P1 ysteelï Izsteel 22.3 ksiïï½ïºï½ Exterior( ) Stress limits: fP1_max Ïconst Fyïïºï½
142 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT fint_P1 fP1_maxï£ 1ï½ fext_P1 fP1_maxï£ 1ï½ Phase 2: Second, check the stress due to dead load on the composite section (with barriers added) Reduction factor for construction Ïconst 0.9ï½ Load Combination for construction 1.25 MDCï Max Moment applied, Phase 2: (at midspan) M2_STR_I 655.8 kip ftïïï½ Capacity for positive flexure: Mn 2246.4 kip ftïïï½ Check Moment: M2_STR_I Ïconst Mnïï£ 1ï½ Phase 3: Next, check the flexural stress on the stringer during transport and picking, to ensure no cracking. Reduction factor for construction Ïconst 0.9ï½ Load Combination for construction 1.5 MDCï when dynamic construction loads are involved (Section 10). Loads and stresses on stringer during transport and picking: M3_STR_I_neg 81.5 kip ftïïï½ Concrete rupture stress fr 0.24 fc ksiïï 0.5 ksiïï½ïºï½ Concrete stress during construction not to exceed: fcmax Ïconst frï 0.5 ksiïï½ïºï½ fcconst M3_STR_I_neg ycï Iz nï 0.1 ksiïï½ïºï½ fcconst fcmaxï£ 1ï½ Phase 4: Check flexural capacity under dead load and live load for fully installed continuous composite girders. Strength I Load Combination Ïf 1.0ïºï½ M4_STR_I 1648 kip ftïïï½ M4_STR_I_neg 1009.8ï kip ftïïï½ M4_STR_I Ïf Mnïï£ 1ï½ M4_STR_I_neg Mr_negï£ 1ï½ Strength III Load Combination M4_STR_III 614.9 kip ftïïï½ M4_STR_III_neg 459.6ï kip ftïïï½ M4_STR_III Ïf Mnïï£ 1ï½ M4_STR_III_neg Mr_negï£ 1ï½ Strength V Load Combination M4_STR_V 1411.9 kip ftïïï½ M4_STR_V_neg 884ï kip ftïïï½ M4_STR_V Ïf Mnïï£ 1ï½ M4_STR_V_neg Mr_negï£ 1ï½ 13. FLEXURAL SERVICE CHECKS Check service load combinations for the fully continuous beam with live load (Phase 4): under Service II for stress limits - M4_SRV_II 1250.7 kip ftïïï½ M4_SRV_II_neg 769.9ï kip ftïïï½ under Service I for cracking - M4_SRV_I_neg 675.6ï kip ftïïï½ Ignore positive moment for Service I as there is no tension in the concrete in this case.
143 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Service Load Stress Limits: Top Flange: ftfmax 0.95 Rhï Fyï 47.5 ksiïï½ïºï½ Bottom Flange: fbfmax ftfmax 47.5 ksiïï½ïºï½ Concrete (Negative bending only): fr 0.5 ksiïï½ Service Load Stresses, Positive Moment: Top Flange: fSRVII_tf M4_SRV_II yc tslabïï¨ ï© Iz ï 3.2 ksiïï½ïºï½ fSRVII_tf ftfmaxï£ 1ï½ Bottom Flange: fbfs2 M4_SRV_II tslab ttfï« Dwï« tbfï« ycïï¨ ï© Iz ï 37.4 ksiïï½ïºï½ fl 0ïºï½ fbfs2 fl 2 ï« fbfmaxï£ 1ï½ Service Load Stresses, Negative Moment: Top (Concrete): fcon.neg M4_SRV_I_neg ycnegï n Iznegï 1.4ï ksiïï½ïºï½ Using Service I Loading fcon.neg frï£ 0ï½ Bottom Flange: fbfs2.neg M4_SRV_I_neg tslab ttfï« Dwï« tbfï« ycnegïï¨ ï©ï Izneg 37.8ï ksiïï½ïºï½ fbfs2.neg fbfmaxï£ 1ï½ Check LL Deflection: ÎDT 1.104 inïïºï½ from independent Analysis - includes 100% design truck (w/impact), or 25% design truck (w/impact) + 100% lane load DFδ 3 12 0.3ï½ïºï½ Deflection distribution factor = (no. lanes)/(no. stringers) Lstr ÎDT DFδï 3021.7ï½ Equivalent X, where L/X = Deflection*Distribution Factor Lstr ÎDT DFδï 800ï³ 1ï½
144 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 14. SHEAR STRENGTH Shear Capacity based on AASHTO LRFD 6.10.9 Nominal resistance of unstiffened web: Fy 50.0 ksiïï½ Dw 28.3 inïï½ tw 0.5 inïï½ Ïv 1.0ïºï½ k 5ïºï½ Vp 0.58 Fyï Dwï twï 426.9 kipïï½ïºï½ C1 1.0 Dw tw 1.12 Es kï Fy ïï£if 1.57 Dw tw ï¦ï§ï¨ ï¶ï·ï¸ 2 Es kï Fy ï¦ï§ï¨ ï¶ï·ï¸ ïï©ïª ïª ïªï« ï¹ïº ïº ïºï» Dw tw 1.40 Es kï Fy ïï¾if 1.12 Dw tw Es kï Fy ïï¦ï§ï§ ï§ï¨ ï¶ï· ï· ï·ï¸ otherwise ïºï½ C1 1ï½ Vn C1 Vpï 426.9 kipïï½ïºï½ Vu Ïv Vnïï£ 1ï½ 15. FATIGUE LIMIT STATES: Fatigue check shall follow LRFD Article 6.10.5. Moments used for fatigue calculations were found using an outside finite element analysis program. First check Fatigue I (infinite life); then find maximum single lane ADTT for Fatigue II if needed. Fatigue Stress Limits: ÎFTH_1 16 ksiïïºï½ Category B: non-coated weathering steel ÎFTH_2 12 ksiïïºï½ Category C': Base metal at toe of transverse stiffener fillet welds ÎFTH_3 10 ksiïïºï½ Category C: Base metal at shear connectors Fatigue Moment Ranges at Detail Locations (from analysis): MFAT_B 301 kipï ftïïºï½ MFAT_CP 285.7 kipï ftïïºï½ MFAT_C 207.1kip ftïïºï½ nfat 2 Lstr 40 ftïï£if 1.0 otherwise ïºï½Î³FATI 1.5ïºï½ γFATII 0.75ïºï½ Constants to use for detail checks: ADTTSL_INF_B 860ïºï½ AFAT_B 120 108ïïºï½ ADTTSL_INF_CP 660ïºï½ AFAT_CP 44 108ïïºï½ ADTTSL_INF_C 1290ïºï½ AFAT_C 44 108ïïºï½ Category B Check: Stress at Bottom Flange, Fatigue I fFATI_B γFATI MFAT_Bï tslab ttfï« Dwï« tbfï« ycïï¨ ï©ï Iz 13.5 ksiïï½ïºï½ fFATI_B ÎFTH_1ï£ 1ï½ fFATII_B γFATII γFATI fFATI_Bï 6.8 ksiïï½ïºï½
145 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ADTTSL_B_MAX ADTTSL_INF_B nfat fFATI_B ÎFTH_1ï£if AFAT_B ksi 3ï 365 75ï nfatï fFATII_B3ï otherwise ïºï½ ADTTSL_B_MAX 860ï½ Category C' Check: Stress at base of transverse stiffener (top of bottom flange) fFATI_CP γFATI MFAT_CPï tslab ttfï« Dwï« ycïï¨ ï© Iz ï 12.5 ksiïï½ïºï½ fFATI_CP ÎFTH_2ï£ 0ï½ fFATII_CP γFATII γFATI fFATI_CPï 6.3 ksiïï½ïºï½ ADTTSL_CP_MAX ADTTSL_INF_CP nfat fFATI_CP ÎFTH_2ï£if AFAT_CP ksi 3ï 365 75ï nfatï fFATII_CP3ï otherwise ïºï½ ADTTSL_CP_MAX 656ï½ Category C Check: Stress at base of shear connectors (top of top flange) fFATI_C γFATI MFAT_Cï yc tslabïï¨ ï© Iz ï 0.8 ksiïï½ïºï½ fFATI_C ÎFTH_3ï£ 1ï½ fFATII_C γFATII γFATI fFATI_Cï 0.4 ksiïï½ïºï½ ADTTSL_C_MAX ADTTSL_INF_C nfat fFATI_C ÎFTH_3ï£if AFAT_C ksi 3ï 365 75ï nfatï fFATII_C3ï otherwise ïºï½ ADTTSL_C_MAX 1290ï½ FATIGUE CHECK: ADTTSL_MAX min ADTTSL_B_MAX ADTTSL_CP_MAXï¬ï ADTTSL_C_MAXï¬ï ï¨ ï©ïºï½ Ensure that single lane ADTT is less than ADTTSL_MAX 656ï½ If not, then the beam requires redesign.
146 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 16. BEARING STIFFENERS bp x tpUsing LRFD Article 6.10.11 for stiffeners: tp 5 8 inïºï½ bp 5inïºï½ Ïb 1.0ïºï½ tp_weld 516 ï¦ï§ï¨ ï¶ï·ï¸inïºï½ 9tw x tw 9tw x tw *Check min weld size Projecting Width Slenderness Check: bp 0.48tp Es Fy ïï£ 1ï½ bp x tp Stiffener Bearing Resistance: Apn 2 bp tp_weldïï¨ ï©ï tpïïºï½ Apn 5.9 in2ïï½ Rsb_n 1.4 Apnï Fyïïºï½ Rsb_n 410.2 kipïï½ Rsb_r Ïb Rsb_nïïºï½ Rsb_r 410.2 kipïï½ RDC 26.721kipïºï½ RDW 2.62kipïºï½ RLL 53.943kipïºï½ ÏDC_STR_I 1.25ïºï½ ÏDW_STR_I 1.5ïºï½ ÏLL_STR_I 1.75ïºï½ Ru ÏDC_STR_I RDCï ÏDW_STR_I RDWïï« ÏLL_STR_I RLLïï«ïºï½ Ru 131.7 kipïï½ Ru Rsb_rï£ 1ï½ Weld Check: throat tp_weld 2 2 ïïºï½ throat 0.2 inïï½ Lweld Dw 2 3ï inïïºï½ Lweld 22.3 inïï½ Aeff_weld throat Lweldïïºï½ Aeff_weld 4.9 in2ïï½ Fexx 70ksiïºï½ Ïe2 0.8ïºï½ Rr_weld 0.6 Ïe2ï Fexxïïºï½ Rr_weld 33.6 ksiïï½ Ru_weld Ru 4 Aeff_weldï ïºï½ Ru_weld 6.7 ksiïï½ Ru_weld Ru_weldï£ 1ï½ Axial Resistance of Bearing Stiffeners: Ïc 0.9ïºï½ Aeff 2 9ï twï tpï«ï¨ ï© twï 2 bpï tpïï«ïºï½ Aeff 11.4 in2ïï½ Leff 0.75 Dwïïºï½ Leff 21.2 inïï½ Ixp 2 9ï twï tw3ï 12 tp 2 bpï twï«ï¨ ï©3ï 12 ï«ïºï½ Ixp 60.7 in4ïï½ Iyp tw tp 2 9ï twïï«ï¨ ï©3ï 12 2bp tp 3ï 12 ï«ïºï½ Iyp 43.3 in4ïï½ rp min Ixp Iypï¬ï ï¨ ï© Aeff ïºï½ rp 1.9 inïï½ Q 1ïºï½ for bearing stiffeners Kp 0.75ïºï½ Po Q Fyï Aeffï 572.1 kipïï½ïºï½
147 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Pe Ï2Es Aeffï Kp Leff rp ïï¦ï§ï¨ ï¶ï·ï¸ 2 48919.6 kipïï½ïºï½ Pn 0.658 Po Pe ï¦ï§ ï¨ ï¶ï· ï¸ ï©ïª ïªï« ï¹ïº ïºï» Poï Pe Po ï¦ï§ï¨ ï¶ï·ï¸ 0.44ï³if 0.877 Peï otherwise ïºï½ Pn 569.3 kipïï½ Pr Ïc Pnïïºï½ Pr 512.4 kipïï½ Ru Prï£ 1ï½ 17. SHEAR CONNECTORS: Shear Connector design to follow LRFD 6.10.10. Stud Properties: ds 7 8 inïïºï½ Diameter hs 6inïºï½ Height of Stud hs ds 4ï³ 1ï½ cs tslab hsïïºï½ cs 2inï³ 1ï½ ss 3.5inïºï½ Spacing ss 4dsï³ 1ï½ ns 3ïºï½ Studs per row btf ss ns 1ïï¨ ï©ïï dsïï©ï« ï¹ï» 2 1.0inï³ 1ï½ Asc Ï ds 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ïïºï½ Asc 0.6 in2ïï½ Fu 60ksiïºï½ Fatigue Resistance: Zr 5.5 ds 2ï kip in2 ïïºï½ Zr 4.2 kipïï½ Qslab Aslab yc yslabïï¨ ï©ïïºï½ Qslab 338.9 in3ïï½ Vf 47.0kipïºï½ Vfat Vf Qslabï Iz 1.5 kip in ïï½ïºï½ ps ns Zrï Vfat 8.7 inïï½ïºï½ 6 dsï psï£ 24inï£ 1ï½ Strength Resistance: Ïsc 0.85ïºï½ fc 5 ksiïï½ Ec 33000 0.15 1.5ï fc ksiï 4286.8 ksiïï½ïºï½ Qn min 0.5 Ascï fc Ecïï Asc Fuïï¬ï ï¨ ï©ïºï½ Qn 36.1 kipïï½ Qr Ïsc Qnïïºï½ Qr 30.7 kipïï½ Psimple min 0.85 fcï beffï tsï Fy Asteelïï¬ï ï¨ ï©ïºï½ Psimple 1436.2 kipïï½ Pcont Psimple min 0.45 fcï beffï tsï Fy Asteelïï¬ï ï¨ ï©ï«ïºï½ Pcont 2282.2 kipïï½ nlines Pcont Qr nsï ïºï½ nlines 24.8ï½
148 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Find required stud spacing along the girder (varies as applied shear varies) i 0 23ï®ï®ïºï½ x 0.00 1.414 4.947 8.480 12.013 15.546 19.079 22.612 26.145 29.678 33.210 33.917 34.624 36.037 36.743 40.276 43.809 47.342 50.875 54.408 57.941 61.474 65.007 67.833 ï¦ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï·ï¸ ftïïºï½ Vfi 61.5 59.2 56.8 54.4 52.0 49.5 47.1 44.7 42.7 40.6 40.6 40.6 40.6 40.6 40.6 42.3 44.2 46.6 49.1 51.5 53.9 56.3 58.7 61.5 ï¦ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï· ï·ï¸ kipïïºï½ Vfati Vfi Qslabï Iz 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1.9 1.8 1.8 1.7 1.6 1.5 1.5 1.4 1.3 1.3 1.3 1.3 1.3 1.3 1.3 ... kip in ïï½ïºï½ Pmax ns Zrï Vfati 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 6.6 6.9 7.2 7.5 7.9 8.3 8.7 9.1 9.6 10.1 10.1 10.1 10.1 10.1 10.1 ... inïï½ïºï½ min Pmaxï¨ ï© 6.6 inïï½ max Pmaxï¨ ï© 10.1 inïï½ 18. SLAB PROPERTIES This section details the geometric and material properties of the deck. Because the equivalent strip method is used in accordance with AASHTO LRFD Section 4, different loads are used for positive and negative bending. Unit Weight Concrete wc 150 pcfïï½ Deck Thickness for Design tdeck 8.0inïºï½ tdeck 7inï³ 1ï½ Deck Thickness for Loads td 10.5 inïï½ Rebar yield strength Fs 60 ksiïï½ Strength of concrete fc 5 ksiïï½ Concrete clear cover Bottom Top cb 1.0inïºï½ cb 1.0inï³ 1ï½ ct 2.5inïºï½ ct 2.5inï³ 1ï½
149 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Transverse reinforcement Bottom Reinforcing Ïtb 68 inïºï½ Ïtt 5 8 inïºï½Top Reinforcing Bottom Spacing stb 8inïºï½ Top Spacing stt 8inïºï½ stb 1.5Ïtbï³ 1.5inï 1ï½ stt 1.5Ïttï³ 1.5inï 1ï½ stb 1.5 tdeckïï£ 18inï 1ï½ stt 1.5 tdeckïï£ 18inï 1ï½ Astb 12in stb Ïï Ïtb 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ï 0.7 in2ïï½ïºï½ Astt 12in stt Ïï Ïtt 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ï 0.5 in2ïï½ïºï½ Design depth of Bar dtb tdeck cb Ïtb 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ï 6.6 inïï½ïºï½ dtt tdeck ct Ïtt 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ï 5.2 inïï½ïºï½ Girder Spacing spacingint_max 4ft 6inï«ïºï½ spacingext 4 ftï½ Equivalent Strip, +M wposM 26 6.6 spacingint_max ft ïï«ï¦ï§ï¨ ï¶ï·ï¸ inïïºï½ wposM 55.7 inïï½ Equivalent Strip, -M wnegM 48 3.0 spacingint_max ft ïï«ï¦ï§ï¨ ï¶ï·ï¸ inïïºï½ wnegM 61.5 inïï½ Once the strip widths are determined, the dead loads can be calculated. 19. PERMANENT LOADS This section calculates the dead loads on the slab. These are used later for analysis to determine the design moments. Weight of deck, +M wdeck_pos wc tdï wposMïïºï½ wdeck_pos 609.2 plfïï½ Weight of deck, -M wdeck_neg wc tdï wnegMïïºï½ wdeck_neg 672.7 plfïï½ Unit weight of barrier wb 433.5plfïºï½ Barrier point load, +M Pb_pos wb wposMïïºï½ Pb_pos 2.01 kipïï½ Barrier point load, -M Pb_neg wb wnegMïïºï½ Pb_neg 2.22 kipïï½ 20. LIVE LOADS This section calculates the live loads on the slab. These loads are analyzed in a separate program with the permanent loads to determine the design moments. Truck wheel load Pwheel 16kipïºï½ Impact Factor IM 1.33ïºï½ Multiple presence factors MP1 1.2ïºï½ MP2 1.0ïºï½ MP3 0.85ïºï½ Wheel Loads P1 IM MP1ï Pwheelïïºï½ P2 IM MP2ï Pwheelïïºï½ P3 IM MP3ï Pwheelïïºï½ P1 25.54 kipïï½ P2 21.3 kipïï½ P3 18.09 kipïï½ 21. LOAD RESULTS A separate finite element analysis program was used to analyze the deck as an 11-span continuous beam with cantilevered overhangs on either end, with supports stationed at girder locations. The dead and live loads were applied separately. The results are represented here as input values, highlighted.
150 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Design Moments Mpos 38.9kip ftïïºï½ Mpos_dist Mpos wposM ïºï½ Mpos_dist 8.38 kip ftï ft ïï½ Mneg 21.0ï kip ftïïºï½ Mneg_dist Mneg wnegM ïºï½ Mneg_dist 4.1ï kip ftï ft ïï½ 22. FLEXURAL STRENGTH CAPACITY CHECK: Consider a 1'-0" strip: Ïb 0.9ïºï½ b 12inïºï½ β1 0.85 fc 4ksiï£if 0.85 0.05 fc ksi 4ïï¦ï§ï¨ ï¶ï·ï¸ïï otherwise ïºï½ β1 0.8ï½ Bottom: Top: ctb Astb Fsï 0.85 fcï β1ï bï 1 inïï½ïºï½ ctt Astt Fsï 0.85 fcï β1ï bï 0.7 inïï½ïºï½ atb β1 ctbï 0.8 inïï½ïºï½ att β1 cttï 0.5 inïï½ïºï½ Mntb Astb Fsï b dtb atb 2 ïï¦ï§ï¨ ï¶ï·ï¸ï 20.7 kip ftï ft ïï½ïºï½ Mntt Astt Fsï ft dtt att 2 ïï¦ï§ï¨ ï¶ï·ï¸ï 11.3 kip ftï ft ïï½ïºï½ Mrtb Ïb Mntbï 18.6 kip ftïftïï½ïºï½ Mrtt Ïb Mnttï 10.2 kip ftï ft ïï½ïºï½ Mrtb Mpos_distï³ 1ï½ Mrtt Mneg_distï³ 1ï½ 23. LONGITUDINAL DECK REINFORCEMENT DESIGN: Longitudinal reinforcement Ïlb 58 inïºï½ slb 12inïºï½ Ïlt 5 8 inïºï½ slt 12inïºï½ Aslb 12in slb Ïï Ïlb 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ï 0.3 in2ïï½ïºï½ Aslt 12in slt Ïï Ïlt 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 0.3 in2ïï½ïºï½ Distribution Reinforcement (AASHTO 9.7.3.2) A%dist min 220 spacingint_max ft 67ï¬ï ï¦ï§ ï§ ï¨ ï¶ï· ï· ï¸ 100 67 %ïï½ïºï½ Adist A%dist Astbï¨ ï©ï 0.4 in2ïï½ïºï½ Aslb Asltï« Adistï³ 1ï½
151 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 24. DESIGN CHECKS This section will conduct design checks on the reinforcing according to various sections in AASHTO LRFD. CHECK MINIMUM REINFORCEMENT (AASHTO LRFD 5.7.3.3.2): Modulus of Rupture fr 0.37 fc ksiïï 0.8 ksiïï½ïºï½ Ec 4286.8 ksiïï½ Es 29000 ksiïï½ Section Modulus Snc b tdeck 2ï 6 128 in3ïï½ïºï½ Adeck tdeck bï 96 in2ïï½ïºï½ ybar_tb Adeck tdeck 2 ï n 1ï( ) Astbï dtbïï« Adeck n 1ï( ) Astbïï« 4.1 inïï½ïºï½ ybar_tt Adeck tdeck 2 ï n 1ï( ) Asttï dttïï« Adeck n 1ï( ) Asttïï« 4 inïï½ïºï½ Itb b tdeck 3ï 12 Adeck tdeck 2 ybar_tbï ï¦ï§ï¨ ï¶ï·ï¸ 2 ïï« n 1ï( ) Astbï dtb ybar_tbïï¨ ï©2ïï« 538.3 in4ïï½ïºï½ Itt b tdeck 3ï 12 Adeck tdeck 2 ybar_ttï ï¦ï§ï¨ ï¶ï·ï¸ 2 ïï« n 1ï( ) Asttï dtt ybar_ttïï¨ ï©2ïï« 515.8 in4ïï½ïºï½ Sc_tb Itb tdeck ybar_tbï 138.2 in3ïï½ïºï½ Sc_tt Itt tdeck ybar_ttï 130 in3ïï½ïºï½ Unfactored Dead Load Mdnc_pos_t 1.25 kip ftï ft ïºï½ Mdnc_neg_t 0.542ï kip ftï ft ïºï½
152 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT S 5.7.3.3.2 Cracking Moment Mcr_tb max Sc_tb frï ft Mdnc_pos_t Sc_tb Snc 1ïï¦ï§ï¨ ï¶ï·ï¸ ïï Sc_tb frï ft ï¬ï ï©ïªï« ï¹ïºï» 9.5 kip ftï ft ïï½ïºï½ Mcr_tt max Sc_tt frï ft Mdnc_neg_t Sc_tt Snc 1ïï¦ï§ï¨ ï¶ï·ï¸ ïï Sc_tt frï ft ï¬ï ï©ïªï« ï¹ïºï» 9 kip ftï ft ïï½ïºï½ Minimum Factored Flexural Resistance Mr_min_tb min 1.2 Mcr_tbï 1.33 Mpos_distïï¬ï ï¨ ï© 11.1 kip ftïftïï½ïºï½ Mrtb Mr_min_tbï³ 1ï½ Mr_min_tt min 1.2 Mcr_ttï 1.33 Mneg_distïï¬ï ï¨ ï© 5.4 kip ftïftïï½ïºï½ Mrtt Mr_min_ttï³ 1ï½ CHECK CRACK CONTROL (AASHTO LRFD 5.7.3.4): γeb 1.0ïºï½ γet 0.75ïºï½ MSL_pos 29.64kip ftïïºï½ MSL_neg 29.64kip ftïïºï½ MSL_pos_dist MSL_pos wposM 6.4 kip ftï ft ïï½ïºï½ MSL_neg_dist MSL_neg wnegM 5.8 kip ftï ft ïï½ïºï½ fssb MSL_pos_dist bï nï Itb dtb ybar_tbï 2.5 ksiïï½ïºï½ fsst MSL_neg_dist bï nï Itt dtt ybar_ttï 1.1 ksiïï½ïºï½ dcb cb Ïtb 2 ï« 1.4 inïï½ïºï½ dct ct Ïtt 2 ï« 2.8 inïï½ïºï½ βsb 1 dcb 0.7 tdeck dcbïï¨ ï©ïï« 1.3ï½ïºï½ βst 1 dct 0.7 tdeck dctïï¨ ï©ïï« 1.8ï½ïºï½ sb 700 γebï kipï βsb fssbï inï 2 dcbïï 212.2 inïï½ïºï½ st 700 γetï kipï βst fsstï inï 2 dctïï 266.5 inïï½ïºï½ stb sbï£ 1ï½ stt stï£ 1ï½ SHRINKAGE AND TEMPERATURE REINFORCING (AASHTO LRFD 5.10.8): Ast 1.30 bï tdeckï 2 b tdeckï«ï¨ ï©ï Fsï kip in ï 0.11in2 1.30 bï tdeckï 2 b tdeckï«ï¨ ï©ï Fsï kip in ïï£ 0.60in2ï£if 0.11in2 1.30 bï tdeckï 2 b tdeckï«ï¨ ï©ï Fsï kip in ï 0.11in2ï¼if 0.60in2 1.30 bï tdeckï 2 b tdeckï«ï¨ ï©ï Fsï kip in ï 0.60in2ï¾if 0.1 in2ïï½ïºï½ Astb Astï³ 1ï½ Astt Astï³ 1ï½ Aslb Astï³ 1ï½ Aslt Astï³ 1ï½ SHEAR RESISTANCE (AASHTO LRFD 5.8.3.3): Ï 0.9ïºï½ β 2ïºï½ θ 45degïºï½ b 1 ftï½
153 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT dv_tb max 0.72 tdeckï dtb atb 2 ïï¬ï 0.9 dtbïï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 6.2 inïï½ïºï½ dv_tt max 0.72 tdeckï dtt att 2 ïï¬ï 0.9 dttïï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 5.8 inïï½ïºï½ dv min dv_tb dv_ttï¬ï ï¨ ï© 5.8 inïï½ïºï½ Vc 0.0316 βï fc ksiïï bï dvï 9.8 kipïï½ïºï½ Vs 0kipïºï½ Shear capacity of reinforcing steel Vps 0kipïºï½ Shear capacity of prestressing steel Vns min Vc Vsï« Vpsï« 0.25 fcï bï dvï Vpsï«ï¬ï ï¨ ï© 9.8 kipïï½ïºï½ Vr Ï Vnsï 8.8 kipïï½ïºï½ Total factored resistance Vus 8.38kipïºï½ Total factored load Vr Vusï³ 1ï½ DEVELOPMENT AND SPLICE LENGTHS (AASHTO LRFD 5.11): Development and splice length design follows standard calculations in AASHTO LRFD 5.11, or as dictated by the State DOT Design Manual. 25. DECK OVERHANG DESIGN (AASHTO LRFD A.13.4): Deck Properties: Deck Overhang Length Lo 1ft 9inï«ïºï½ Parapet Properties: Note: Parapet properties are per unit length. Compression reinforcement is ignored. Cross Sectional Area Ap 2.84ft 2ïºï½ Height of Parapet Hpar 2ft 10inï«ïºï½ Parapet Weight Wpar wc Apï 426 plfïï½ïºï½ Width at base wbase 1ft 5inï«ïºï½ Average width of wall wwall 13in 9.5inï« 2 11.3 inïï½ïºï½ Height of top portion of parapet h1 2ftïºï½ Width at top of parapet width1 9.5 inï 9.5 inïï½ïºï½ Height of middle portion of parapet h2 7inïºï½ Width at middle transition of parapet width2 12 inï 12 inïï½ïºï½
154 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Height of lower portion of parapet h3 3inïºï½ Width at base of parapet width3 1ft 5 inïï« 17 inïï½ïºï½ b1 width1ïºï½ b2 width2 width1ïïºï½ b3 width3 width2ïïºï½ Parapet Center of Gravity CGp h1 h2ï« h3ï«ï¨ ï© b1 2 2 ï 1 2 h1ï b2ï b1 b2 3 ï«ï¦ï§ï¨ ï¶ï·ï¸ïï« h2 h3ï«ï¨ ï© b2 b3ï«ï¨ ï©ï b1 b2 b3ï«2ï« ï¦ï§ï¨ ï¶ï·ï¸ï 1 2 h2ï b3ï b1 b2ï« 2b3 3 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïï« ï®ï®ï® h1 h2ï« h3ï«ï¨ ï© b1ï 12 h1ï b2ïï« h2 h3ï«ï¨ ï© b2 b3ï«ï¨ ï©ïï« 1 2 h2ï b3ïï 6.3 inïï½ïºï½ Parapet Reinforcement Vertically Aligned Bars in Wall Horizontal Bars Rebar spacing: spa 12inïºï½ npl 5ïºï½ Rebar Diameter: Ïpa 58 inïºï½ Ïpl 5 8 inïºï½ Rebar Area: Ast_p Ï Ïpa 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ï b spa ï 0.3 in2ïï½ïºï½ Asl_p Ï Ïpl 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ï 0.3 in2ïï½ïºï½ Cover: cst 3inïºï½ csl 2in Ïpaï« 2.6 inïï½ïºï½ Effective Depth: dst wbase cstï Ïpa 2 ï 13.7 inïï½ïºï½ dsl wwall cslï Ïpl 2 ï 8.3 inïï½ïºï½ Parapet Moment Resistance About Horizontal Axis: Ïext 1.0ïºï½ S 5.7.3.1.2-4 S 5.7.3.2.3 Depth of Equivalent Stress Block: ah Ast_p Fsï 0.85 fcï bï 0.4 inïï½ïºï½ Moment Capacity of Upper Segment of Barrier (about longitudinal axis): Average width of section w1 width1 width2ï« 2 10.7 inïï½ïºï½ Cover cst1 2inïºï½ dh1 w1 cst1ï Ïpa 2 ï 8.4 inïï½ïºï½Depth Factored Moment Resistance ÏMnh1 Ïext Ast_pï Fsï dh1 ah 2 ïï¦ï§ï¨ ï¶ï·ï¸ï b 12.7 kip ftï ft ïï½ïºï½ Moment Capacity of Middle Segment of Barrier (about longitudinal axis): Average width of section w2 width2 width3ï« 2 14.5 inïï½ïºï½ Cover cst2 3inïºï½ dh2 w2 cst2ï Ïpa 2 ï 11.2 inïï½ïºï½Depth Factored Moment Resistance ÏMnh2 Ïext Ast_pï Fsï dh2 ah 2 ïï¦ï§ï¨ ï¶ï·ï¸ï b 16.9 kip ftï ft ïï½ïºï½
155 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Parapet Base Moment Resistance (about longitudinal axis): development in tension cst3 3inïºï½ coverbase_vert cst3 Ïpa 2 ï« 3.3 inïï½ïºï½ minc_ta 1.5 cst3 3 Ïpaïï¼ spa Ïpaï 6 Ïpaïï¼ïif 1.2 otherwise 1.2ï½ïºï½ mdec_ta 0.8 spa 6inï³if 1.0 otherwise 0.8ï½ïºï½ ldb_ta max 1.25in Ast_pï Fs kip ï fc ksi 0.4 Ïpaï Fs ksi ïï¬ï ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ Ïpa 118 inï£if 2.70in Fs ksi ï fc ksi Ïpa 148 in=if 3.50in Fs ksi ï fc ksi Ïpa 188 in=if ïºï½ ldt_ta ldb_ta minc_taï mdec_taï 14.4 inïï½ïºï½ hooked bar developed in tension lhb_ta 38 Ïpaï fc ksi 10.6 inïï½ïºï½ minc 1.2ï½ ldh_ta max 6in 8 Ïpaïï¬ï minc lhb_taïï¬ï ï¨ ï© 12.7 inïï½ïºï½ lap splice in tension llst_ta max 12in 1.3 ldt_taïï¬ï ï¨ ï© 18.7 inïï½ïºï½ benefit ldt_ta ldh_taï 1.7 inïï½ïºï½ ldev_a 7 13 16 ï«ï¦ï§ï¨ ï¶ï·ï¸inïºï½ Fdev benefit ldev_aï« ldt_ta 0.7ï½ïºï½ Fd 0.75ïºï½ Distance from NA to Compressive Face ct_b Fd Ast_pï Fsï 0.85 fcï β1ï bï 0.3 inïï½ïºï½ S 5.7.3.1.2-4 Depth of Equivalent Stress Block at β1 ct_bï 0.3 inïï½ïºï½ S 5.7.3.2.3 Nominal Moment Resistance Mnt Fd Ast_pï Fsï dst at 2 ïï¦ï§ï¨ ï¶ï·ï¸ï 15.6 kip ftïïï½ïºï½ S 5.7.3.2.2-1 Factored Moment Resistance Mcb Ïext Mnt ft ï 15.6 kip ftï ft ïï½ïºï½ S 5.7.3.2 Average Moment Capacity of Barrier (about longitudinal axis):
156 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Factored Moment Resistance about Horizontal Axis Mc ÏMnh1 h1ï ÏMnh2 h2ïï« Mcb h3ïï« h1 h2ï« h3ï« 13.8 kip ftï ft ïï½ïºï½ Parapet Moment Resistance (about vertical axis): Height of Transverse Reinforcement in Parapet y1 5inïºï½ Width of Parapet at Transverse Reinforcement x1 width3 y1 h3ïï¨ ï© b3ï h2 ï 15.6 inïï½ïºï½ y2 11.5inïºï½ x2 b1 b2ï« y2 h3ï h2ïï¨ ï© b2ï h1 ï 11.8 inïï½ïºï½ y3 18inïºï½ x3 b1 b2ï« y3 h3ï h2ïï¨ ï© b2ï h1 ï 11.2 inïï½ïºï½ y4 24.5inïºï½ x4 b1 b2ï« y4 h3ï h2ïï¨ ï© b2ï h1 ï 10.5 inïï½ïºï½ y5 31inïºï½ x5 b1 b2ï« y5 h3ï h2ïï¨ ï© b2ï h1 ï 9.8 inïï½ïºï½ Depth of Equivalent Stress Block a npl Asl_pï Fsï 0.85 fcï Hparï 0.6 inïï½ïºï½ Concrete Cover in Parapet coverr 2inïºï½ coverrear coverr Ïpaï« Ïpl 2 ï« 2.9 inïï½ïºï½ coverbase cst3 Ïpaï« Ïpl 2 ï« 3.9 inïï½ïºï½ coverf 2inïºï½ coverfront 2in Ïpaï« Ïpl 2 ï«ïºï½ covert x5 2 4.9 inïï½ïºï½ covertop covert 4.9 inïï½ïºï½ Design depth d1i x1 coverbaseï 11.6 inïï½ïºï½ d1o x1 coverrearï 12.6 inïï½ïºï½ d2i x2 coverfrontï 8.9 inïï½ïºï½ d2o x2 coverrearï 8.9 inïï½ïºï½ d3i x3 coverfrontï 8.2 inïï½ïºï½ d3o x3 coverrearï 8.2 inïï½ïºï½ d4i x4 coverfrontï 7.6 inïï½ïºï½ d4o x4 coverrearï 7.6 inïï½ïºï½ d5i x5 covertopï 4.9 inïï½ïºï½ d5o x5 covertopï 4.9 inïï½ïºï½ Nominal Moment Resistance - Tension on Inside Face ÏMn1i Ïext Asl_pï Fsï d1i a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 208.3 kip inïïï½ïºï½ ÏMn2i Ïext Asl_pï Fsï d2i a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 158.1 kip inïïï½ïºï½ ÏMn3i Ïext Asl_pï Fsï d3i a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 145.6 kip inïïï½ïºï½ ÏMn4i Ïext Asl_pï Fsï d4i a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 133.2 kip inïïï½ïºï½ ÏMn5i Ïext Asl_pï Fsï d5i a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 84.5 kip inïïï½ïºï½ Mwi ÏMn1i ÏMn2iï« ÏMn3iï« ÏMn4iï« ÏMn5iï« 60.8 kip ftïïï½ïºï½ Nominal Moment Resistance - Tension on Outside Face ÏMn1o Ïext Asl_pï Fsï d1o a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 18.9 kip ftïïï½ïºï½ ÏMn2o Ïext Asl_pï Fsï d2o a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 13.2 kip ftïïï½ïºï½ ÏMn3o Ïext Asl_pï Fsï d3o a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 12.1 kip ftïïï½ïºï½
157 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ÏMn4o Ïext Asl_pï Fsï d4o a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 11.1 kip ftïïï½ïºï½ ÏMn5o Ïext Asl_pï Fsï d5o a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 7 kip ftïïï½ïºï½ Mwo ÏMn1o ÏMn2oï« ÏMn3oï« ÏMn4oï« ÏMn5oï« 62.3 kip ftïïï½ïºï½ Vertical Nominal Moment Resistance of Parapet Mw 2 Mwiï Mwoï« 3 61.3 kip ftïïï½ïºï½ Parapet Design Factors: Crash Level CL "TL-4"ïºï½ Transverse Design Force Ft 13.5kip CL "TL-1"=if 27.0kip CL "TL-2"=if 54.0kip CL "TL-3"=if 54.0kip CL "TL-4"=if 124.0kip CL "TL-5"=if 175.0kip otherwise 54 kipïï½ïºï½ Lt 4.0ft CL "TL-1"=if 4.0ft CL "TL-2"=if 4.0ft CL "TL-3"=if 3.5ft CL "TL-4"=if 8.0ft CL "TL-5"=if 8.0ft otherwise 3.5 ftïï½ïºï½ Longitudinal Design Force Fl 4.5kip CL "TL-1"=if 9.0kip CL "TL-2"=if 18.0kip CL "TL-3"=if 18.0kip CL "TL-4"=if 41.0kip CL "TL-5"=if 58.0kip otherwise 18 kipïï½ïºï½ Ll 4.0ft CL "TL-1"=if 4.0ft CL "TL-2"=if 4.0ft CL "TL-3"=if 3.5ft CL "TL-4"=if 8.0ft CL "TL-5"=if 8.0ft otherwise 3.5 ftïï½ïºï½ Vertical Design Force (Down) Fv 4.5kip CL "TL-1"=if 4.5kip CL "TL-2"=if 4.5kip CL "TL-3"=if 18.0kip CL "TL-4"=if 80.0kip CL "TL-5"=if 80.0kip otherwise 18 kipïï½ïºï½ Lv 18.0ft CL "TL-1"=if 18.0ft CL "TL-2"=if 18.0ft CL "TL-3"=if 18.0ft CL "TL-4"=if 40.0ft CL "TL-5"=if 40.0ft otherwise 18 ftïï½ïºï½ Critical Length of Yield Line Failure Pattern: Mb 0kip ftïïºï½ Lc Lt 2 Lt 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 8 Hparï Mb Mwï«ï¨ ï©ï Mc ï«ï« 11.9 ftïï½ïºï½ S A13.3.1-2 Rw 2 2 Lcï Ltï 8 Mbï 8 Mwïï« Mc Lc 2ï Hpar ï« ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ï 116.2 kipïï½ïºï½ S A13.3.1-1 T Rw bï Lc 2 Hparïï« 6.6 kipïï½ïºï½ S A13.4.2-1
158 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT The parapet design must consider three design cases. Design Case 1 is for longitudinal and transverse collision loads under Extreme Event Load Combination II. Design Case 2 represents vertical collision loads under Extreme Event Load Combination II; however, this case does not govern for decks with concrete parapets or barriers. Design Case 3 is for dead and live load under Strength Load Combination I; however, the parapet will not carry wheel loads and therefore this case does not govern. Design Case 1 is the only case that requires a check. Design Case 1: Longitudinal and Transverse Collision Loads, Extreme Event Load Combination II DC - 1A: Inside face of parapet S A13.4.1 S Table 3.4.1-1Ïext 1ï½ Î³DC 1.0ïºï½ γDW 1.0ïºï½ γLL 0.5ïºï½ llip 2inïºï½ wbase 17 inïï½ Adeck_1A tdeck llip wbaseï«ï¨ ï©ï 152 in2ïï½ïºï½ Ap 2.8 ft2ïï½ Wdeck_1A wc Adeck_1Aï 0.2 klfïï½ïºï½ Wpar 0.4 klfïï½ MDCdeck_1A γDC Wdeck_1Aï llip wbaseï« 2 ï 0.1 kip ftï ft ïï½ïºï½ MDCpar_1A γDC Wparï llip CGpï«ï¨ ï©ï 0.3 kip ftïftïï½ïºï½ Mtotal_1A Mcb MDCdeck_1Aï« MDCpar_1Aï« 16 kip ftï ft ïï½ïºï½ Ïtt_add 58 inïºï½ stt_add 8inïºï½ Astt_p 12in stt Ïï Ïtt 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ï 12in stt_add Ïï Ïtt_add 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ïï« 0.9 in2ïï½ïºï½ dtt_add tdeck ct Ïtt_add 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ï 5.2 inïï½ïºï½ ctt_p Astt_p Fsï 0.85 fcï β1ï bï 1.4 inïï½ïºï½ att_p β1 ctt_pï 1.1 inïï½ïºï½ Mntt_p Astt_p Fsï ft dtt_add att_p 2 ïï¦ï§ï¨ ï¶ï·ï¸ï 21.4 kip ftï ft ïï½ïºï½ Mrtt_p Ïb Mntt_pï 19.2 kip ftïftïï½ïºï½ Mrtt_p Mtotal_1Aï³ 1ï½ AsT Astt Astbï« 1.1 in2ïï½ïºï½ ÏPn Ïext AsTï Fsï 67.4 kipïï½ïºï½ ÏPn Tï³ 1ï½ Mu_1A Mrtt_p 1 T ÏPnï ï¦ï§ï¨ ï¶ï·ï¸ ï 17.4 kip ftï ft ïï½ïºï½ Mu_1A Mtotal_1Aï³ 1ï½ DC - 1B: Design Section in Overhang Notes: Distribution length is assumed to increase based on a 30 degree angle from the face of parapet. Moment of collision loads is distributed over the length Lc + 30 degree spread from face of parapet to location of overhang design section. Axial force of collision loads is distributed over the length Lc + 2Hpar + 30 degree spread from face of parapet to location of overhang design section. Future wearing surface is neglected as contribution is negligible. Adeck_1B tdeck Loï 168 in2ïï½ïºï½ Ap 2.8 ft2ïï½
159 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Wdeck_1B wc Adeck_1Bï 0.2 klfïï½ïºï½ Wpar 0.4 klfïï½ MDCdeck_1B γDC Wdeck_1Bï Lo 2 ï 0.2 kip ftï ft ïï½ïºï½ MDCpar_1B γDC Wparï Lo llipï CGpïï¨ ï©ï 0.5 kip ftïftïï½ïºï½ Lspread_B Lo llipï width3ï 2 inïï½ïºï½ spread 30degïºï½ wspread_B Lspread_B tan spread( )ï 1.2 inïï½ïºï½ Mcb_1B Mcb Lcï Lc 2 wspread_Bïï« 15.3 kip ftï ft ïï½ïºï½ Mtotal_1B Mcb_1B MDCdeck_1Bï« MDCpar_1Bï« 15.9 kip ftï ft ïï½ïºï½ Mrtt_p 19.2 kip ftï ft ïï½ Mrtt_p Mtotal_1Bï³ 1ï½ ÏPn 67.4 kipïï½ Pu T Lc 2 Hparïï«ï¨ ï©ï Lc 2 Hparïï« 2 wspread_Bïï« 6.5 kipïï½ïºï½ ÏPn Puï³ 1ï½ Mu_1B Mrtt_p 1 Pu ÏPnï ï¦ï§ï¨ ï¶ï·ï¸ ï 17.4 kip ftï ft ïï½ïºï½ Mu_1B Mtotal_1Bï³ 1ï½ DC - 1C: Design Section in First Span Assumptions: Moment of collision loads is distributed over the length Lc + 30 degree spread from face of parapet to location of overhang design section. Axial force of collision loads is distributed over the length Lc + 2Hpar + 30 degree spread from face of parapet to location of overhang design section. Future wearing surface is neglected as contribution is negligible. Mpar_G1 MDCpar_1B 0.5 kip ftï ft ïï½ïºï½ Mpar_G2 0.137ï kip ftï ft ïºï½ (From model output) M1 Mcb 15.6 kip ftï ft ïï½ïºï½ M2 M1 Mpar_G2 Mpar_G1 ï 4.7ï kip ftï ft ïï½ïºï½ bf 10.5inïºï½ Mc_M2M1 M1 1 4 bfï M1ï M2ï«ï¨ ï©ï spacingint_max ï« 14.6 kip ftï ft ïï½ïºï½ Lspread_C Lo llipï wbaseï bf 4 ï« 4.6 inïï½ïºï½ wspread_C Lspread_C tan spread( )ï 2.7 inïï½ïºï½ Mcb_1C Mc_M2M1 Lcï Lc 2 wspread_Cïï« 14.1 kip ftï ft ïï½ïºï½
160 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Mtotal_1C Mcb_1C MDCdeck_1Bï« MDCpar_1Bï« 14.7 kip ftï ft ïï½ïºï½ Mrtt_p 19.2 kip ftï ft ïï½ Mrtt_p Mtotal_1Cï³ 1ï½ ÏPn 67.4 kipïï½ PuC T Lc 2 Hparïï«ï¨ ï©ï Lc 2 Hparïï« 2 wspread_Cïï« 6.4 kipïï½ïºï½ ÏPn PuCï³ 1ï½ Mu_1C Mrtt_p 1 Pu ÏPnï ï¦ï§ï¨ ï¶ï·ï¸ ï 17.4 kip ftï ft ïï½ïºï½ Mu_1B Mtotal_1Bï³ 1ï½ Compute Overhang Reinforcement Cut-off Length Requirement Maximum crash load moment at theoretical cut-ff point: Mc_max Mrtt 10.2 kip ftï ft ïï½ïºï½ LMc_max M2 Mrttï M2 M1ï spacingint_maxï 3.3 ftïï½ïºï½ Lspread_D Lo llipï wbaseï LMc_maxï« 41.6 inïï½ïºï½ wspread_D Lspread_D tan spread( )ï 24 inïï½ïºï½ Mcb_max Mc_max Lcï Lc 2 wspread_Dïï« 7.6 kip ftï ft ïï½ïºï½ extension max dtt_add 12 Ïtt_addïï¬ï 0.0625 spacingint_maxïï¬ï ï¨ ï© 7.5 inïï½ïºï½ cutt_off LMc_max extensionï« 47.1 inïï½ïºï½ Att_add Ï Ïtt_add 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 ï 0.3 in2ïï½ïºï½ mthick_tt_add 1.4 tdeck ctï 12inï³if 1.0 otherwise 1ï½ïºï½ mepoxy_tt_add 1.5 ct 3 Ïtt_addïï¼ stt_add 2 Ïtt_addï 6 Ïtt_addïï¼ïif 1.2 otherwise 1.5ï½ïºï½ minc_tt_add min mthick_tt_add mepoxy_tt_addï 1.7ï¬ï ï¨ ï© 1.5ï½ïºï½ mdec_tt_add 0.8 stt_add 2 6inï³if 1.0 otherwise 1ï½ïºï½
161 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ldb_tt_add max 1.25in Att_addï Fs kip ï fc ksi 0.4 Ïtt_addï Fs ksi ïï¬ï ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ Ïtt_add 118 inï£if 2.70in Fs ksi ï fc ksi Ïtt_add 148 in=if 3.50in Fs ksi ï fc ksi Ïtt_add 188 in=if ïºï½ ldb_tt_add 15 inïï½ ldt_tt_add ldb_tt_add minc_tt_addï mdec_tt_addï 22.5 inïï½ïºï½ Cuttoffpoint LMc_max ldt_tt_addï« spacingint_maxï 8.1 inïï½ïºï½ extension past second interior girder Check for Cracking in Overhang under Service Limit State: Does not govern - no live load on overhang. 25. COMPRESSION SPLICE: See sheet S7 for drawing. Ensure compression splice and connection can handle the compressive force in the force couple due to the negative moment over the pier. Live load negative moment over pier: MLLPier 541.8 kipï ftïïºï½ Factored LL moment: MUPier 1.75 MLLPierï 948.1 kip ftïïï½ïºï½ The compression splice is comprised of a splice plate on the underside of the bottom flange, and built-up angles on either side of the web, connecting to the bottom flange as well. Calculate Bottom Flange Stress: Composite moment of inertia: Iz 10959.8 in 4ïï½ Distance to center of bottom flange from composite section centroid: ybf tbf 2 Dwï« ttfï« tslabï« ycï 27 inïï½ïºï½ Stress in bottom flange: fbf MUPier ybf Iz ï 28 ksiïï½ïºï½ Calculate Bottom Flange Force: Design Stress: Fbf max fbf Fyï« 2 0.75 Fyïï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 39 ksiïï½ïºï½ Effective Flange Area: Aef bbf tbfï 7 in2ïï½ïºï½ Force in Flange: Cnf Fbf Aefï 273.2 kipïï½ïºï½ Calculate Bottom Flange Stress, Ignoring Concrete: Moment of inertia: Izsteel 3923.8 in 4ïï½ Distance to center of bottom flange: ybfsteel tbf 2 Dwï« ttfï« ysteelï 14.5 inïï½ïºï½
162 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Stress in bottom flange: fbfsteel MUPier ybfsteel Izsteel ï 42 ksiïï½ïºï½ Bottom Flange Force for design: Design Stress: Fcf max fbfsteel Fyï« 2 0.75 Fyïï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 46 ksiïï½ïºï½ Design Force: Cn max Fbf Fcfï¬ï ï¨ ï© Aefï 322.1 kipïï½ïºï½ Compression Splice Plate Dimensions: Bottom Splice Plate: bbsp bbf 10.4 inïï½ïºï½ tbsp 0.75inïºï½ Absp bbsp tbspï 7.8 in2ïï½ïºï½ Built-Up Angle Splice Plate Horizontal Leg: basph 4.25inïºï½ tasph 0.75inïºï½ Aasph 2 basphï tasphï 6.4 in 2ïï½ïºï½ Built-Up Angle Splice Plate Vertical Leg: baspv 7.75inïºï½ taspv 0.75inïºï½ Aaspv 2 baspvï taspvï 11.6 in 2ïï½ïºï½ Total Area: Acsp Absp Aasphï« Aaspvï« 25.8 in2ïï½ïºï½ Average Stress: fcs Cn Acsp 12.5 ksiïï½ïºï½ Proportion Load into each plate based on area: Cbsp Cn Abspï Acsp 97.7 kipïï½ïºï½ Casph Cn Aasphï Acsp 79.5 kipïï½ïºï½ Caspv Cn Aaspvï Acsp 144.9 kipïï½ïºï½ Check Plates Compression Capacity: Bottom Splice Plate: kcps 0.75ïºï½ for bolted connection lcps 9inïºï½ rbsp min bbsp tbsp 3ï 12 tbsp bbsp 3ï 12 ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ Absp 0.2 inïï½ïºï½ Pebsp Ï2 Esï Abspï kcps lcpsï rbsp ï¦ï§ï¨ ï¶ï·ï¸ 2 2307.9 kipïï½ïºï½ Qbsp 1.0 bbsp tbsp 0.45 Es Fy ïï£if 1.34 0.76 bbsp tbsp ï¦ï§ï¨ ï¶ï·ï¸ ï Fy Es ïïï©ïªï« ï¹ïºï» 0.45 Es Fy ï bbsp tbsp ï£ 0.91 Es Fy ïï£if 0.53 Esï Fy bbsp tbsp ï¦ï§ï¨ ï¶ï·ï¸ 2 ï otherwise 0.9ï½ïºï½ Pobsp Qbsp Fyï Abspï 352.8 kipïï½ïºï½
163 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Pnbsp 0.658 Pobsp Pebsp ï¦ï§ ï¨ ï¶ï· ï¸ ï©ïª ïªï« ï¹ïº ïºï» Pobspï ï©ïª ïªï« ï¹ïº ïºï» Pebsp Pobsp 0.44ï³if 0.877 Pebspïï¨ ï© otherwise 330.9 kipïï½ïºï½ Pnbsp_allow 0.9 Pnbspï 297.8 kipïï½ïºï½ Check "NG" Cbsp Pnbsp_allowï³if "OK" Pnbsp_allow Cbspï³if "OK"ï½ïºï½ Horizontal Angle Leg: kcps 0.75ï½ for bolted connection lcps 9 inïï½ rasph min basph tasph 3ï 12 tasph basph 3ï 12 ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ Aasph 0.153 inïï½ïºï½ Peasph Ï2 Esï Aasphï kcps lcpsï rasph ï¦ï§ï¨ ï¶ï·ï¸ 2 938.6 kipïï½ïºï½ Qasph 1.0 basph tasph 0.45 Es Fy ïï£if 1.34 0.76 basph tasph ï¦ï§ï¨ ï¶ï·ï¸ ï Fy Es ïïï©ïªï« ï¹ïºï» 0.45 Es Fy ï basph tasph ï£ 0.91 Es Fy ïï£if 0.53 Esï Fy basph tasph ï¦ï§ï¨ ï¶ï·ï¸ 2 ï otherwise 1ï½ïºï½ Poasph Qasph Fyï Aasphï 318.7 kipïï½ïºï½ Pnasph 0.658 Poasph Peasph ï¦ï§ ï¨ ï¶ï· ï¸ ï©ïª ïªï« ï¹ïº ïºï» Poasphï ï©ïª ïªï« ï¹ïº ïºï» Peasph Poasph 0.44ï³if 0.877 Peasphïï¨ ï© otherwise 276.5 kipïï½ïºï½ Pnasph_allow 0.9 Pnasphï 248.9 kipïï½ïºï½ Check2 "NG" Casph Pnasph_allowï³if "OK" Pnasph_allow Casphï³if "OK"ï½ïºï½ Vertical Angle Leg: kcps 0.75ï½ for bolted connection lcps 9 inïï½ raspv min baspv taspv 3ï 12 taspv baspv 3ï 12 ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ Aaspv 0.153 inïï½ïºï½ Peaspv Ï2 Esï Aaspvï kcps lcpsï raspv ï¦ï§ï¨ ï¶ï·ï¸ 2 1711.6 kipïï½ïºï½
164 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Qaspv 1.0 baspv taspv 0.45 Es Fy ïï£if 1.34 0.76 baspv taspv ï¦ï§ï¨ ï¶ï·ï¸ ï Fy Es ïïï©ïªï« ï¹ïºï» 0.45 Es Fy ï baspv taspv ï£ 0.91 Es Fy ïï£if 0.53 Esï Fy baspv taspv ï¦ï§ï¨ ï¶ï·ï¸ 2 ï otherwise 1ï½ïºï½ Poaspv Qaspv Fyï Aaspvï 581.2 kipïï½ïºï½ Pnaspv 0.658 Poaspv Peaspv ï¦ï§ ï¨ ï¶ï· ï¸ ï©ïª ïªï« ï¹ïº ïºï» Poaspvï ï©ïª ïªï« ï¹ïº ïºï» Peaspv Poaspv 0.44ï³if 0.877 Peaspvïï¨ ï© otherwise 504.2 kipïï½ïºï½ Pnaspv_allow 0.9 Pnaspvï 453.8 kipïï½ïºï½ Check3 "NG" Caspv Pnaspv_allowï³if "OK" Pnaspv_allow Caspvï³if "OK"ï½ïºï½ Additional Checks: Design Bolted Connections of the splice plates to the girders, checking for shear, bearing, and slip critical connections. 26. CLOSURE POUR DESIGN: See sheet S2 for drawing of closure pour. Check the closure pour according to the negative bending capacity of the section. Use the minimum reinforcing properties for design, to be conservative. Asteel 28.7 in 2ïï½ Art 1.8 in2ïï½ Arb 2.6 in2ïï½ cgsteel tslab ysteelï« 22.8 inïï½ïºï½ cgrt 3in 1.5 5 8 inïï« 3.9 inïï½ïºï½ cgrb tslab 1in 1.5 5 8 ï inï«ï¦ï§ï¨ ï¶ï·ï¸ï 6.1 inïï½ïºï½ Overall CG: Aneg Asteel Artï« Arbï« 33.1 in2ïï½ïºï½ cgneg Asteel cgsteelï Art cgrtïï« Arb cgrbïï« Aneg 20.5 inïï½ïºï½ Moment of Inertia: Izstl 3990in 4ïºï½ Ineg Izstl Asteel cgsteel cgnegïï¨ ï©2ïï« Art cgrt cgnegïï¨ ï©2ïï« Arb cgrb cgnegïï¨ ï©2ïï« 5183.7 in4ïï½ïºï½ Section Moduli: Stop_neg Ineg cgneg cgrtï 313.4 in3ïï½ïºï½ rneg Ineg Aneg 12.5 inïï½ïºï½ Sbot_neg Ineg tslab ttfï« Dwï« tbfï« cgnegïï¨ ï© 301.9 in 3ïï½ïºï½ Concrete Properties: fc 5 ksiïï½ Steel Properties: Fy 50 ksiïï½ Lbneg 13.42ftïºï½ Ec 4286.8 ksiïï½ Es 29000 ksiïï½
165 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Fyr 0.7 Fyï 35 ksiïï½ïºï½ Negative Flexural Capacity: Slenderness ratio for compressive flange: λfneg bbf 2 tbfï 7.8ï½ïºï½ Limiting ratio for compactness: λpfneg 0.38 Es Fy ï 9.2ï½ïºï½ Limiting ratio for noncompact λrfneg 0.56 Es Fyr ï 16.1ï½ïºï½ Hybrid Factor: Rh 1ï½ Dcneg2 Dw 2 14.2 inïï½ïºï½ awc 2 Dcneg2ï twï bbf tbfï 2.1ï½ïºï½ Rb 1.0 2 Dcneg2 tw ï 5.7 Es Fy ïï£if min 1.0 1 awc 1200 300 awcïï« 2 Dcneg2 tw ï 5.7 Es Fy ïïï¦ï§ï¨ ï¶ï·ï¸ ïïï¬ï ï©ïªï« ï¹ïºï» otherwise ïºï½ Rb 1ï½ Flange compression resistance: Fnc1 Rb Rhï Fyï λfneg λpfnegï£if 1 1 Fyr Rh Fyï ïï¦ï§ï¨ ï¶ï·ï¸ λfneg λpfnegïï¨ ï© Î»rfneg λpfnegïï¨ ï©ïï ï©ïªï« ï¹ïºï» Rbï Rhï Fyï ï©ïªï« ï¹ïºï» otherwise ïºï½ Fnc1 50 ksiïï½ Lateral Torsional Buckling Resistance: rtneg bbf 12 1 Dcneg2 twï 3 bbfï tbfï ï«ï¦ï§ï¨ ï¶ï·ï¸ ï 2.6 inïï½ïºï½ Lpneg 1.0 rtnegï Es Fy ï 62.5 inïï½ïºï½ Lrneg Ï rtnegï Es Fyr ï 234.7 inïï½ïºï½ Cb 1ï½ Fnc2 Rb Rhï Fyï Lbneg Lpnegï£if min Cb 1 1 Fyr Rh Fyï ïï¦ï§ï¨ ï¶ï·ï¸ Lbneg Lpnegïï¨ ï© Lrneg Lpnegïï¨ ï©ïï ï©ïªï« ï¹ïºï» ï Rbï Rhï Fyï Rb Rhï Fyïï¬ï ï©ïªï« ï¹ïºï» ïºï½ Fnc2 41.4 ksiïï½ Compressive Resistance: Fnc min Fnc1 Fnc2ï¬ï ï¨ ï© 41.4 ksiïï½ïºï½ Tensile Flexural Resistance: Fnt Rh Fyï 50 ksiïï½ïºï½ For Strength
166 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Fnt_Serv 0.95 Rhï Fyï 47.5 ksiïï½ïºï½ For Service Ultimate Moment Resistance: Mn_neg min Fnt Stop_negï Fnc Sbot_negïï¬ï ï¨ ï© 1042 kip ftïïï½ïºï½ MUPier 948.1 kip ftïïï½ from external FE analysis Check4 Mn_neg MUPierï³ 1ï½ïºï½ For additional design, one may calculate the force couple at the section over the pier to find the force in the UHPC closure joint. This force can be used to design any additional reinforcement used in the joint.
167 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ABC SAMPLE CALCULATION â 2 Decked Precast Prestressed Concrete girder Design for ABC
168 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT  DECKED PRECAST PRESTRESSED CONCRETE GIRDER DESIGN FOR ABC Unit Definition: kcf kip ft 3ïïïº This example is for the design of a superstructure system that can be used for rapid bridge replacement in an Accelerated Bridge Construction (ABC) application. The following calculations are intended to provide the designer guidance in developing a similar design with regard to design considerationS characteristic of this type of construction, and they shall not be considered fully exhaustive. Overall Width, W Roadway Width, WrBarrier Width, Wb Joint Width, Wj Slope, CS Beam Spacing, SS Wjï 2 TYPICAL SECTION THROUGH SPAN Lend Design Span Length, L Girder Length, Lg GIRDER ELEVATION Bridge Geometry: L 70 ftïïºï½ Lend 2 ftïïºï½ skew 0 degïïºï½ W 47.167 ftïïºï½ Wb 1.5 ftïïºï½ Smax 8 ftïïºï½ Wj 0.5 ftïïºï½ Ng ceil W Wjï« Smax ï¦ï§ï¨ ï¶ï·ï¸ 6ï½ïºï½ Minimum number of girders in cross-section S W Wjï« Ng 7.945 ftïï½ïºï½ Girder spacing
169 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ORDER OF CALCULATIONS Introduction1. Design Philosophy2. Design Criteria3. Beam Section4. Material Properties5. Permanent Loads6. Precast Lifting Weight7. Live Load8. Prestress Properties9. Prestress Losses10. Concrete Stresses11. Flexural Strength12. Shear Strength13. Splitting Resistance14. Camber and Deflections15. Negative Moment Flexural Strength16. 1. INTRODUCTION The superstructure system considered here consists of precast prestressed concrete girders with a top flange width nominally equal to the beam spacing, such that the top flange will serve as the riding surface once closure joints between the girders are poured. The intended use of these girders is to facilitate rapid bridge construction by providing a precast deck on the girder, thereby eliminating the need for a cast-in-place deck in the field. Concepts used in this example are taken from previous and on-going research, the focus of which is overcoming issues detracting from the benefits of decked precast beams and promoting widespread acceptance by transportation agencies and the construction industry. The cross-section is adapted from the optimized girder sections recommended by NCHRP Project No. 12-69, Design and Construction Guidelines for Long-Span Decked Precast, Prestressed Concrete Girder Bridges. The section considered here has an additional 3" added to the top flange to accommodate the joint continuity detail utilized in this project. The girder design does not include the option to re-deck because the final re-decked system, without additional prestressing, is generally expected to have a shorter span length capability, effectively under-utilizing the initial precast section. Sacrifical wearing thickness, use of stainles steel rebars and the application of a future membrane and wearing surface can mitigate the need to replace the deck, so these characteristics are included in lieu of "re-deckability". The bridge used in this example represents a typical design problem. The calculations are equally as applicable to a single-span or multiple-span bridge because beam design moments are not reduced for continuity in multiple-span bridges at intermediate support. Design of the continuity details is not addressed in this example. The cross-section consists of a two-lane roadway with normal crown, bordered by standard barrier wall along each fascia. The structural system is made up of uniformly spaced decked precast prestressed concrete girders set normal to the cross-slope to allow for a uniform top flange and to simplify bearing details. The girder flanges are 9" at the tips, emulating an 8" slab with an allowance (1/2") for wear and an additional allowance (1/2") for grinding for smoothness and profile adjustment. The intent of this example is the illustrate aspects of design unique to decked precast prestressed girders used in an ABC application. Prestress forces and concrete stresses at the service limit states due to the uncommon cross-section, unusually high self-weight, and unconventional sequence of load application are of particular concern, and appropriate detailed calculations are included. Flexure and shear at the strength limit state are not anticipated to differ significantly from a conventional prestressed beam design. With the exception of computing flexural resistance at midspan, flexure and shear are omitted from this example for brevity. Omission of these checks does not indicate they are not necessary, nor does it relieve the designer of the responsibility to satisfy any and all design requirements, as specified by AASHTO and the Owner.
170 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 2. DESIGN PHILOSOPHY Geometry of the section is selected based on availability of standard formwork across many geographic regions, as evidenced by sections commonly used by many state transporation agencies. Depth variations are limited to constant-thickness region of the web, maintaining the shapes of the top flange and bottom bulb. Concrete strengths can vary widely, and strengths ranging from below 6 ksi to over 10 ksi are common. For the purposes of these calculations, concrete with a 28-day minimum compressive strength of 8 ksi is used. Because this beam is unable to take advantage of the benefits of composite behavior due to its casting sequence, and because allowable tension in the bottom of the beam at the service limit state is limited (discussed in Section 4), end region stresses are expected to be critical. Therefore, minimum concrete strength at release is required to be 80 percent of the 28-day compressive strength of the concrete, increasing the allowable stresses at the top and bottom of the section. The prestressing steel can also be optimized to minimize the stresses in the end region, as discussed below. Prestressing steel is arranged in a draped, or harped, pattern in order to maximize its effectiveness at midspan while minimizing its eccentricity at the ends of the beam where the concrete is easily overstressed because there is little positive dead load moment to offset the negative prestress moment. Effectiveness of the strand group is optimized at midspan by bundling the harped strands between hold-down points, maximizing the eccentricity of the strand group. The number and deflection angle of the harped strands is constrained by an upper limit on the hold-down force required for a single strand and for a single hold-down device, i.e., the entire group of strands. For longer spans, concrete stresses in the end regions at release will be excessive, and debonding without harped strands is not likely to reduce stresses to within allowable limits. Therefore, since harped strands will be required, this method of stress relief will be used exclusively without debonding. Temporary strands are not considered. 3. DESIGN CRITERIA In addition to the provisions of AASHTO, several criteria have been selected to govern the design of these beams, based on past and current practice, as well as research related to decked precast sections and accelerated bridge construction. The following is a summary of limiting design values for which the beams are proportioned, and they are categorized as section constraints, prestress limits, and concrete limits: Section Constraints: Wpc.max 200 kipïïºï½ Upper limit on the weight of the entire precast element, based on common lifting and transport capabilities without significantly increasing time and/or cost due to unconventional equipment or permits Smax 8 ftïï½ Upper limit on girder spacing and, therefore, girder flange width (defined on first page) Prestress Limits: Fhd.single 4 kipïïºï½ Maximum hold-down force for a single strand Fhd.group 48 kipïïºï½ Maximum hold-down force for the group of harped strands Stress limits in the prestressing steel immediately prior to prestress and at the service limit state after all losses are as prescribed by AASHTO LRFD.
171 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 3. DESIGN CRITERIA (cont'd) Concrete Limits: Allowable concrete stresses are generally in line with AASHTO LRFD requirements, with one exception. Allowable tension in the bottom of the section at final, Service III, is limited to 0 ksi, based on the research of NCHRP Project No. 12-69. Imposing this limitation precludes the need to evaluate the flexural effects on the girder section arising from forces applied to correct differential camber between adjacent beams. The reliability of this approach is enhanced without the need for additional calculations by specifying a differential camber tolerance equally as, or more stringent than, the tolerance assumed in the subject project. For the purposes of this example, the differential camber tolerance is assumed be at least as stringent. ft.all.ser 0 ksiïïºï½ Allowable bottom fiber tension at the Service III Limit State, when camber leveling forces are to be neglected, regardless of exposure As previously mentioned, release concrete strength is specified as 80 percent of the minimum 28-day compressive strength to maximize allowable stresses in the end region of beam at release. fc.rel f( ) 0.80 fïïºï½ Minimum strength of concrete at release At the intermediate erection stage, stresses in the beam due to various lifting and transportation support conditions need to be considered. Using AASHTO LRFD Table 5.9.4.2.1-1, allowable compression during handling can be limited to 60% of the concrete strength. This provision is not explicitly applicable to this case, however, it does apply to handling stresses in prestressed piling and is more appropriate than the more restrictive sustained permanent load limit of 45% due to anticipated dynamic dead load effects. For allowable tension, a "no cracking" approach is considerd due to reduced lateral stability after cracking. Therefore, allowable tension is limited to the modulus of rupture, further modified by an appropriate factor of safety. Both allowable values are based on the concrete strength at the time of lifting and transportation. At this stage, assuming the beams will be lifted sometime after release and before the final strength is attained, allowable stresses are based on the average of the release strength and the specified 28-day strength, i.e., 90% of the specified strength. DIM 30%ïºï½ Dynamic dead load allowance fc.erec f( ) 0.90 fïïºï½ Assumed attained concrete strength during lifting and transportation FSc 1.5ïºï½ Factor of safety against cracking during lifting transportation ft.erec f( ) 0.24ï f ksiïï FSc ïºï½ Allowable tension in concrete during lifting and transportation to avoid cracking
172 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT b1 b2 b3 bn+1 bn bn-1 bn-2 dn dn-1 dn-2 d1 d2 TYPICAL GIRDER SECTION COMPRISED  OF n TRAPEZOIDAL REGIONS y x 4. BEAM SECTION Use trapezoidal areas to define the cross-section. The flange width is defined as the beam spacing less the width of the longitudinal closure joint to reflect pre-erection conditions. Live load can be conservatively applied to this section, as well. h 42 inïïºï½ Beam section depth tflange 9 inïïºï½ Flange thickness at tip tsac 1 inïïºï½ Total sacrificial depth for grinding and wear b1 26 inïïºï½ b2 26 inïïºï½ d1 7 inïïºï½ b2 26 inïï½ b3 6 inïïºï½ d2 3 inïïºï½ b3 6 inïï½ b4 6 inïïºï½ b4 6 inïï½ b5 10 inïïºï½ d4 2 inïïºï½ b5 10 inïï½ b6 49 inïïºï½ d5 3 inïïºï½ b6 49 inïï½ b7 S Wjïïºï½ d6 0 inïïºï½ b7 89.334 inïï½ b8 S Wjïïºï½ d7 tflange tsacïïºï½ d3 h tsacï dï¥ïïºï½ d3 18 inïï½ Gross Section Properties bf 89.334 inïï½ Precast girder flange width Ag 1157.172 in 2ïï½ Cross-sectional area (does not include sacrifical thickness) Ixg 203462 in 4ïï½ Moment of inertia (does not include sacrificial thickness) ytg 12.649 inïï½ ybg 28.351ï inïï½ Top and bottom fiber distances from neutal axis (positive up) Stg 16085.5 in 3ïï½ Sbg 7176.5ï in3ïï½ Top and bottom section moduli Iyg 493395 in 4ïï½ Weak-axis moment of inertia 50ï 40ï 30ï 20ï 10ï 0 10 20 30 40 502ï 3.75 9.5 15.25 21 26.75 32.5 38.25 44 GIRDER SECTION PLOT (N.T.S.)
173 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 5. MATERIAL PROPERTIES Concrete: fc 8 ksiïïºï½ Minimum 28-day compressive strength of concrete fci fc.rel fcï¨ ï© 6.4 ksiïï½ïºï½ Minimum strength of concrete at release γc .150 kcfïïºï½ Unit weight of concrete K1 1.0ïºï½ Correction factor for standard aggregate (5.4.2.4) Eci 33000 K1ï γc kcf ï¦ï§ï¨ ï¶ï·ï¸ 1.5 ï fci ksiïï 4850 ksiïï½ïºï½ Modulus of elasticity at release (5.4.2.4-1) Ec 33000 K1ï γc kcf ï¦ï§ï¨ ï¶ï·ï¸ 1.5 ï fc ksiïï 5422 ksiïï½ïºï½ Modulus of elasticity (5.4.2.4-1) fr.cm 0.37 fc ksiïï 1.047 ksiïï½ïºï½ Modulus of rupture for cracking moment (5.4.2.6) fr.cd 0.24 fc ksiïï 0.679 ksiïï½ïºï½ Modulus of rupture for camber and deflection (5.4.2.6) H 70ïºï½ Relative humidity (5.4.2.3) Prestressing Steel: fpu 270 ksiïïºï½ Ultimate tensile strength fpy 0.9 fpuï 243 ksiïï½ïºï½ Yield strength, low-relaxation strand (Table 5.4.4.1-1) fpbt.max 0.75 fpuï 202.5 ksiïï½ïºï½ Maximum stress in steel immediately prior to transfer fpe.max 0.80 fpyï 194.4 ksiïï½ïºï½ Maximum stress in steel after all losses Ep 28500 ksiïïºï½ Modulus of elasticity (5.4.4.2) dps 0.5 inïïºï½ Strand diameter Ap 0.153 in 2ïïºï½ Strand area Nps.max 40ïºï½ Maximum number of strands in section npi Ep Eci 5.9ï½ïºï½ Modular ratio at release np Ep Ec 5.3ï½ïºï½ Modular ratio Mild Steel: fy 60 ksiïïºï½ Specified minimum yield strength Es 29000 ksiïïºï½ Modulus of elasticity (5.4.3.2)
174 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 6. PERMANENT LOADS Permanent loads to be considered in the design of this girder are self-weight, diaphragms, barrier, and future wearing surface. The barrier can be cast with the beam, superimposed on the exterior girder only in the field, or superimposed on the bridge after the closure joints have attained sufficient strength. Distribution of the barrier weight to the girders should accurately reflect the stage at which it was installed. In this example, the barrier is assumed to be cast on the exterior girder in the casting yard, after release of prestress, but prior to shipping. This concept increases the dead load to be supported by the exterior girder while eliminating a time-consuming task to be completed in the field. BeamLoc 1ïºï½ Location of beam within the cross-section (0 - Interior, 1 - Exterior) Load at Release: γc.DL .155 kcfïïºï½ Concrete density used for weight calculations Ag.DL Ag tsac S Wjïï¨ ï©ïï« 1246.506 in2ïï½ïºï½ Area used for weight calculations, including sacrificial thickness wg Ag.DL γc.DLï 1.342 klfïï½ïºï½ Uniform load due to self-weight, including sacrificial thickness Lg L 2 Lendïï« 74 ftïï½ïºï½ Span length at release Mgr x( ) wg xï 2 Lg xïï¨ ï©ïïºï½ Moment due to beam self-weight (supported at ends) Vgr x( ) wg Lg 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Shear due to beam self-weight (supported at ends) Load at Erection: Mg x( ) wg xï 2 L xï( )ïïºï½ Moment due to beam self-weight Vg x( ) wg L 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Shear due to beam self-weight wbar 0.430 klfïïºï½ Uniform load due to barrier weight, exterior beams only wbar if BeamLoc 1= wbarï¬ï 0ï¬ï ï¨ ï© 0.43 klfïï½ïºï½ Redfine to 0 if interior beam (BeamLoc = 0) Mbar x( ) wbar xï 2 L xï( )ïïºï½ Moment due to beam self-weight Vbar x( ) wbar L 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Shear due to beam self-weight
175 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 6. PERMANENT LOADS (cont'd) Load at Service: pfws 25 psfïïºï½ Assumed weight of future wearing surface wfws pfws Sï 0.199 klfïï½ïºï½ Uniform load due to future wearing surface Mfws x( ) wfws xï 2 L xï( )ïïºï½ Moment due to future wearing surface Vfws x( ) wfws L 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Shear due to future wearing surface wj Wj d7ï γc.DLï 0.052 klfïï½ïºï½ Uniform load due to weight of longitudinal closure joint Mj x( ) wj xï 2 L xï( )ïïºï½ Moment due to longitudinal closure joint Vj x( ) wj L 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Shear due to longitudinal closure joint
176 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 7. PRECAST LIFTING WEIGHT Precast Superstructure Wg wg wbarï«ï¨ ï© Lgï 131.1 kipïï½ïºï½ Precast girder, including barrier if necessary Substructure Precast with Superstructure Lcorb 1 ftïïºï½ Length of approach slab corbel Bcorb bfïºï½ bf 89.334 inïï½ Width of corbel cast with girder Dcorb 1.5 ftïïºï½ Average depth of corbel Vcorb Lcorb Bcorbï Dcorbï 11.17 ft3ïï½ïºï½ Volume of corbel Lia 2.167 ftïïºï½ Length of integral abutment Lgia 1.167 ftïïºï½ Length of girder embedded in integral abutment Bia S Wjï 7.444 ftïï½ïºï½ Width of integral abutment cast with girder Dia h 4 inïï« 46 inïï½ïºï½ Depth of integral abutment Via Vcorb Lia Biaï Diaï Ag tflange bfïïï¨ ï© Lgiaïïï©ï« ï¹ï»ï« 70.14 ft3ïï½ïºï½ Volume of integral abutment cast with girder Wia Via γcï 11 kipïï½ïºï½ Weight of integral abutment cast with girder Lsa 2.167 ftïïºï½ Length of semi-integral abutment Lgsa 4 inïïºï½ Length of girder embedded in semi-integral abutment Bsa S Wjï 7.444 ftïï½ïºï½ Width of semi-integral abutment cast with girder Dsa h 16 inïï« 58 inïï½ïºï½ Depth of semi-integral abutment Vsa Vcorb Lsa Bsaï Dsaï Ag tflange bfïïï¨ ï© Lgsaïïï©ï« ï¹ï»ï« 88.32 ft3ïï½ïºï½ Volume of semi-integral abutment cast with girder Wsa Vsa γcï 13 kipïï½ïºï½ Weight of semi-integral abutment cast with girder
177 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Semi-Integral Abutment Backwall Integral Abutment Backwall
178 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 8. LIVE LOAD Vehicular loading conforms to the HL-93 design load prescribed by AASHTO. If project-specific erection schemes require the bridge to support construction loads at any stage of erection, these loads should be considered as a separate load case and applied to the beam section at an appropriate attained age of the concrete. Longitudinal joint is designed and detailed for a full moment connection. Therefore, the beams are considered "sufficiently connected to act as a unit" and distribution factors are computed for cross-section type "j", as defined in AASHTO 4.6.2.2. For purposes of computing the longitudinal stiffness parameter, the constant-depth region of the top flange is treated as the slab and the remaining area of the beam section is considered the non-composite beam. Distribution Factors for Moment: From Table 4.6.2.2.2b-1 for moment in interior girders, Ibb 59851 in 4ïï½ Moment of inertia of section below the top flange Abb 442.5 in 2ïï½ Area of beam section below the top flange eg h tsac ts 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ï ybbï« 22.617 inïï½ïºï½ Distance between c.g.'s of beam and flange Kg 1.0 Ibb Abb eg 2ïï«ï¦ï¨ ï¶ï¸ï 286209 in4ïï½ïºï½ Longitudinal stiffness parameter (Eqn. 4.6.2.2.1-1) Verify this girder design is within the range of applicability for Table 4.6.2.2.2b-1. CheckMint if S 16 ftïï£( ) S 3.5 ftïï³( )ï ts 4.5 inïï³ï¨ ï©ï ts 12.0 inïï£ï¨ ï©ï L 20 ftïï³( )ï L 240 ftïï£( )ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï»ïºï½ CheckMint if CheckMint "OK"=( ) Ng 4ï³ï¨ ï©ï Kg 10000 in4ïï³ï¦ï¨ ï¶ï¸ï Kg 7000000 in4ïï£ï¦ï¨ ï¶ï¸ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï»ïºï½ CheckMint "OK"ï½ gmint1 0.06 S 14 ftï ï¦ï§ï¨ ï¶ï·ï¸ 0.4 S L ï¦ï§ï¨ ï¶ï·ï¸ 0.3 ï Kg L ts 3ï ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ 0.1 ïï« 0.458ï½ïºï½ Single loaded lane gmint2 0.075 S 9.5 ftï ï¦ï§ï¨ ï¶ï·ï¸ 0.6 S L ï¦ï§ï¨ ï¶ï·ï¸ 0.2 ï Kg L ts 3ï ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ 0.1 ïï« 0.633ï½ïºï½ Two or more loaded lanes gmint max gmint1 gmint2ï¬ï ï¨ ï© 0.633ï½ïºï½ Distribution factor for moment at interior beams
179 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 8. LIVE LOAD (cont'd) From Table 4.6.2.2.2d-1 for moment in exterior girders, de S 2 Wbï 29.667 inïï½ïºï½ CheckMext if de 1ï ftïï³ï¨ ï© de 5.5 ftïï£ï¨ ï©ï Ng 4ï³ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½ For a single loaded lane, use the Lever Rule. gmext1 S 0.5 bfïï« Wbï 5 ftïïï¨ ï© S 0.65ï½ïºï½ Single loaded lane em 0.77 de 9.1 ftïï« 1.042ï½ïºï½ gmext2 em gmintï 0.659ï½ïºï½ Two or more loaded lanes gmext max gmext1 gmext2ï¬ï ï¨ ï© 0.659ï½ïºï½ Distribution factor for moment at exterior beams Distribution Factors for Shear: From Table 4.6.2.2.3a-1 for shear in interior girders, Verify this girder design is within the range of applicability for Table 4.6.2.2.3a-1. CheckVint if S 16 ftïï£( ) S 3.5 ftïï³( )ï ts 4.5 inïï³ï¨ ï©ï ts 12.0inï£ï¨ ï©ï L 20 ftïï³( )ï L 240 ftïï£( )ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï»ïºï½ CheckVint if CheckMint "OK"=( ) Ng 4ï³ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï»ïºï½ CheckVint "OK"ï½ gvint1 0.36 S 25 ftï ï¦ï§ï¨ ï¶ï·ï¸ï« 0.678ï½ïºï½ Single loaded lane gvint2 0.2 S 12 ftï ï¦ï§ï¨ ï¶ï·ï¸ï« S 35 ftï ï¦ï§ï¨ ï¶ï·ï¸ 2.0 ï 0.811ï½ïºï½ Two or more loaded lanes gvint max gvint1 gvint2ï¬ï ï¨ ï© 0.811ï½ïºï½ Distribution factor for shear at interior beams
180 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 8. LIVE LOAD (cont'd) From Table 4.6.2.2.3b-1 for shear in exterior girders, For a single loaded lane, use the Lever Rule. CheckVext if de 1ï ftïï³ï¨ ï© de 5.5 ftïï£ï¨ ï©ï Ng 4ï³ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½ g1 S 0.5 bfïï« Wbï 5 ftïïï¨ ï© S 0.65ï½ïºï½ Single loaded lane (same as for moment) ev 0.6 de 10 ftïï« 0.847ï½ïºï½ g2 ev gvintï 0.687ï½ïºï½ Two or more loaded lanes gvext max g1 g2ï¬ï ï¨ ï© 0.687ï½ïºï½ Distribution factor for shear at exterior beams From Table 4.6.2.2.3c-1 for skewed bridges, θ skew 0 degïï½ïºï½ CheckSkew if θ 60 degïï£( ) 3.5 ftï Sï£ 16 ftïï£( )ï 20 ftï Lï£ 240 ftïï£( )ï Ng 4ï³ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½ cskew 1.0 0.20 L ts 3ï Kg ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ 0.3 ï tan θ( )ïï« 1.00ï½ïºï½ Correction factor for skew
181 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 8. LIVE LOAD (cont'd) Design Live Load Moment at Midspan: wlane 0.64 klfïïºï½ Design lane load Ptruck 32 kipïïºï½ Design truck axle load IM 33%ïºï½ Dynamic load allowance (truck only) Mlane x( ) wlane xï 2 L xï( )ïïºï½ Design lane load moment Influence coefficient for truck moment calculationδ x( ) x Lï x 2ï L ïºï½ Mtruck x( ) Ptruck δ x( )ï max 9 xï L xï( )ï 14 ftï 3 xï Lï«( )ïï4 xï L xï( )ï 9 L xï( )ï 84 ftïï 4 L xï( )ïï¬ï ï©ïªï« ï¹ïºï»ïïºï½ Design truck moment MHL93 x( ) Mlane x( ) 1 IMï«( ) Mtruck x( )ïï«ïºï½ HL93 design live load moment per lane Mll.i x( ) MHL93 x( ) gmintïïºï½ Design live load moment at interior beam Mll.e x( ) MHL93 x( ) gmextïïºï½ Design live load moment at exterior beam Mll x( ) if BeamLoc 1= Mll.e x( )ï¬ï Mll.i x( )ï¬ï ï¨ ï©ïºï½ Design live load moment Design Live Load Shear: Vlane x( ) wlane L 2 xïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Design lane load shear Vtruck x( ) Ptruck 9 Lï 9 xïï 84 ftïï 4 Lï ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Design truck shear VHL93 x( ) Vlane x( ) 1 IMï«( ) Vtruck x( )ïï«ïºï½ HL93 design live load shear Vll.i x( ) VHL93 x( ) gvintïïºï½ Design live load shear at interior beam Vll.e x( ) VHL93 x( ) gvextïïºï½ Design live load shear at exterior beam Vll x( ) if BeamLoc 1= Vll.e x( )ï¬ï Vll.i x( )ï¬ï ï¨ ï©ïºï½ Design live load shear
182 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 9. PRESTRESS PROPERTIES Because allowable tension at the service limit state is reduced to account for camber leveling forces, the prestress force required at midspan is expected to be excessive in the ends at release without measures to reduce the prestress moment. Estimate losses and prestress eccentricity at midspan to select a trial prestress force that results in a bottom fiber tension stress less than allowable. Compute instantaneous losses in the prestressing steel and check release stresses at the end of the beam. Once end stresses are satisfied, estimate total loss of prestress. As long as computed losses do not differ significantly from the assumed values, the prestress layout should be adequate. Concrete stresses at all limit states are evaluated in Section 9. yp.est 5 inïïºï½ Assumed distance from bottom of beam to centroid of prestress at midspan ycgp.est ybg yp.estï« 23.35ï inïï½ïºï½ Eccentricity of prestress from neutral axis, based on assumed location Îfp.est 25%ïºï½ Estimate of total prestress losses at the service limit state Compute bottom fiber service stresses at midspan using gross section properties. X L 2 ïºï½ Distance from support Mdl.ser Mg X( ) Mfws X( )ï« Mj X( )ï« Mbar X( )ï« 1238 kip ftïïï½ïºï½ Total dead load moment fb.serIII Mdl.ser 0.8 Mll X( )ïï« Sbg 3.567ï ksiïï½ïºï½ Total bottom fiber service stress fpj fpbt.max 202.5 ksiïï½ïºï½ Prestress jacking force fpe.est fpj 1 Îfp.estïï¨ ï©ï 151.9 ksiïï½ïºï½ Estimate of effective prestress force Aps.est Ag fb.serIIIï ft.all.serï« fpe.est ï¦ï§ï¨ ï¶ï·ï¸ 1 Ag ycgp.estï Sbg ï« ï 5.703 in2ïï½ïºï½ Estimated minimum area of prestressing steel Nps.est ceil Aps.est Ap ï¦ï§ï¨ ï¶ï·ï¸ 38ï½ïºï½ Estimated number of strands required Nps 38ïºï½ Number of strands used ( Nps.max 40ï½ ) This number is used to lay out the strand pattern and compute an actual location and eccentricity of the strand group, after which, the required area is computed again. If the location estimate was accurate, the recomputed number of strands should not differ from the number defined here. If the estimate was low, consider increasing the number of strands. It should be noted that the number of strands determined in this section is based on assumed prestressed losses and gross section properties and may not accurately reflect the final number of strands required to satisfy design requirements. Concrete stresses are evaluated in Section 10. Strand pattern geometry calculations assume a vertical spacing of 2" between straight strands, as well as harped strands at the ends of the beam. Harped strands are bundled at midpsan,where the centroid of these strands is 5" from the bottom
183 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 9. PRESTRESS PROPERTIES (cont'd) Nh 2 Nps 12ï£if 4 12 Npsï¼ 24ï£if 6 24 Npsï¼ 30ï£if 6 Nps 30ïï¨ ï©ï« Nps 30ï¾if ïºï½ Nh 14ï½ Assumes all flange rows are filled prior to filling rows in web above the flange, which maximized efficiency. Use override below to shift strands from flange to web if needed to satisfy end stresses. Additional harped strands in web (strands to be moved from flange to web)Nh.add 16ïºï½ 16 strands or half of total strands maximum harped in webNh min Nh Nh.addï« 16ï¬ï 2 floor Nps 4 ï¦ï§ï¨ ï¶ï·ï¸ïï¬ï ï¦ï§ï¨ ï¶ï·ï¸ïºï½ Nh 16ï½ yh 1 inï 2 inï( ) 1 0.5 Nhï 1ï 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïï«ïºï½ yh 10 inïï½ Centroid of harped strands from bottom, equallyspaced yhb 5 inïïºï½ Centroid of harped strands from bottom, bundled Ns Nps Nhïïºï½ Ns 22ï½ Number of straight strands in flange ys 1 inï 2 inï Ns 10ï£if 4 inï( ) Nsï 20 inïï Ns 10 Nsï¼ 20ï£if 6 inï( ) Nsï 60 inïï Ns 20 Nsï¼ 24ï£if 3.5 inï otherwise ï«ïºï½ ys 4.273 inïï½ Centroid of straight strands from bottom yp Ns ysï Nh yhbïï« Ns Nhï« 4.579 inïï½ïºï½ Centroid of prestress from bottom at midspan ycgp ybg ypï« 23.77ï inïï½ïºï½ Eccentricity of prestress from neutral axis Aps.req Ag fb.serIIIï ft.all.serï« fpe.est ï¦ï§ï¨ ï¶ï·ï¸ 1 Ag ycgpï Sbg ï« ï 5.623 in2ïï½ïºï½ Estimated minimum area of prestressing steel Nps.req ceil Aps.req Ap ï¦ï§ï¨ ï¶ï·ï¸ 37ï½ïºï½ Estimated number of strands required CheckNps if Nps Nps.maxï£ï¨ ï© Nps.req Npsï£ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½ Aps.h Nh Apï 2.448 in2ïï½ïºï½ Area of prestress in web (harped) Aps.s Ns Apï 3.366 in2ïï½ïºï½ Area of prestress in flange (straight)
184 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Aps Aps.h Aps.sï« 5.814 in2ïï½ïºï½ Total area of prestress 9. PRESTRESS PROPERTIES (cont'd) Compute transformed section properties based on prestress layout. Transformed Section Properties Initial Transformed Section (release): Final Transformed Section (service): Ati 1185.5 in 2ïï½ Atf 1181.9 in2ïï½ Ixti 219101 in 4ïï½ Ixtf 217153 in4ïï½ ytti 13.217 inïï½ Stti 16577 in3ïï½ yttf 13.146 inïï½ Sttf 16518 in3ïï½ ycgpi 23.204ï inïï½ Scgpi 9442ï in3ïï½ ycgpf 23.275ï inïï½ Scgpf 9330ï in3ïï½ ybti 27.783ï inïï½ Sbti 7886ï in3ïï½ ybtf 27.854ï inïï½ Sbtf 7796ï in3ïï½ Determine initial prestress force after instantaneous loss due to elastic shortening. Use transformed properties to compute stress in the concrete at the level of prestress. Pj fpj Apsï 1177.3 kipïï½ïºï½ Jacking force in prestress, prior to losses Stress in concrete at the level of prestress after instantaneous lossesfcgpi Pj 1 Ati ycgpi Scgpi ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mgr Lg 2 ï¦ï§ï¨ ï¶ï·ï¸ Scgpi ï« 2.719 ksiïï½ïºï½ Prestress loss due to elastic shortening (5.9.5.2.3a-1)ÎfpES npi fcgpiï 15.978 ksiïï½ïºï½ fpi fpj ÎfpESï 186.522 ksiïï½ïºï½ Initial prestress after instantaneous losses Pi fpi Apsï 1084.4 kipïï½ïºï½ Initial prestress force Determine deflection of harped strands required to satisfy allowable stresses at the end of the beam at release. fc.all.rel 0.6 fciï 3.84 ksiïï½ïºï½ Allowable compression before losses (5.9.4.1.1) ft.all.rel max 0.0948ï fci ksiïï 0.2ï ksiïï¬ï ï¨ ï© 0.200ï ksiïï½ïºï½ Allowable tension before losses (Table 5.9.4.1.2-1) Lt 60 dpsï 2.5 ftïï½ïºï½ Transfer length (AASHTO 5.11.4.1) ycgp.t ft.all.rel Mgr Ltï¨ ï© Stti ï Pi 1 Ati ï ï¦ï§ ï§ ï§ï¨ ï¶ï· ï· ï·ï¸ Sttiï 18.367ï inïï½ïºï½ Prestress eccentricity required for tension
185 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ycgp.b fc.all.rel Mgr Ltï¨ ï© Sbti ï Pi 1 Ati ï ï¦ï§ ï§ ï§ï¨ ï¶ï· ï· ï·ï¸ Sbtiï 22.6ï inïï½ïºï½ Prestress eccentricity required for compression 9. PRESTRESS PROPERTIES (cont'd) ycgp.req max ycgp.t ycgp.bï¬ï ï¨ ï© 18.367ï inïï½ïºï½ Required prestress eccentricity at end of beam Minimum distance to harped prestress centroid from bottom of beam at centerline of bearingyh.brg.req ycgp.req ybtiïï¨ ï© Ns Nhï«ï¨ ï©ï ys Nsïï Nh 16.488 inïï½ïºï½ Minimum distance between uppermost strand and top of beamytop.min 18 inïïºï½ αhd 0.4ïºï½ Hold-down point, fraction of the design span length Maximum slope of an individual strand to limit hold-down force to 4 kips/strandslopemax if dps 0.6 inï= 1 12 ï¬ï 1 8 ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 0.125ï½ïºï½ Set centroid of harped strands as high as possible to minimize release and handling stressesyh.brg h ytop.minï 0.5 Nhï 1ï 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 inï( )ïï 17 inïï½ïºï½ yh.brg min yh.brg yhb slopemax αhdï Lïï«ï¬ï ï¨ ï© 17 inïï½ïºï½ Verify that slope requirement is satisfied at uppermost strand CheckEndPrestress if yh.brg yh.brg.reqï³ "OK"ï¬ï "Verify release stresses."ï¬ï ï¨ ï© "OK"ï½ïºï½ yp.brg Ns ysï Nh yh.brgïï« Ns Nhï« 9.632 inïï½ïºï½ Centroid of prestress from bottom at bearing slopecgp yp.brg ypï αhd Lï 0.015ï½ïºï½ Slope of prestress centroid within the harping length ypx x( ) yp slopecgp Lend αhd Lïï« xïï¨ ï©ïï« x Lend αhd Lïï«ï£if yp otherwise ïºï½ Distance to center of prestress from the bottom of the beam at any position
186 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 10. PRESTRESS LOSSES As with any prestressed concrete design, total prestress loss can be considered as the sum of instantaneous (short-term) and time-dependent (long-term) losses. For pretensioned girders, the instantaneous loss consists of elastic shortening of the beam upon release of the prestress force. The time-dependendent losses consist of creep and shrinkage of beam concrete, creep and shrinkage of deck concrete, and relaxation of the prestressing steel. These long-term effects in the girder are further subdivided into two stages to represent a significant event in the construction of the bridge: time between transfer of the prestress force and placement of the deck, and the period of time between placement of the deck and final service. For the specific case of a decked beam, computation of long-term losses is somewhat simplified because the cross-section does not change between these two stages and the term related to shrinkage of the deck concrete is eliminated since the deck is cast monolithically with the beam. There will be no gains or losses in the steel associated with deck placement after transfer. AASHTO provides two procedures for estimating time-dependent losses: Approximate Estimate (5.9.5.3)1. Refined Estimate (5.9.5.4)2. The approximate method is intended for systems with composite decks and is based upon assumptions related to timing of load application, the cross-section to which load is applied (non-composite or composite), and ratios of dead load and live load to total load. The conditions under which these beams are to be fabricated, erected, and loaded differ from the conditions assumed in development of the approximate method. Therefore, the refined method is used to estimate time-dependent losses in the prestressing steel. Time-dependent loss equations of 5.9.5.4 include age-adjusted transformed section factors to permit loss computations using gross section properties. Assumed time sequence in the life of the girder for loss calculations: ti 1ïºï½ Time (days) between casting and release of prestress tb 20ïºï½ Time (days) to barrier casting (exterior girder only) td 30ïºï½ Time (days) to erection of precast section, closure joint pour tf 20000ïºï½ Time (days) to end of service life Terms and equations used in the loss calculations: Prestressing steel factor for low-relaxation strands (C5.9.5.4.2c)KL 45ïºï½ VS Ag Peri 4.023 inïï½ïºï½ Volume-to-surface ratio of the precast section ks max 1.45 0.13 VS in ïï 1.0ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 1.00ï½ïºï½ Factor for volume-to-surface ratio (5.4.2.3.2-2) khc 1.56 0.008 Hïï 1.00ï½ïºï½ Humidity factor for creep (5.4.2.3.2-3) khs 2.00 0.014 Hïï 1.02ï½ïºï½ Humidity factor for shrinkage (5.4.2.3.3-2) kf 5 1 fci ksi ï« 0.676ï½ïºï½ Factor for effect of concrete strength (5.4.2.3.2-4)
187 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 10. PRESTRESS LOSSES (cont'd) ktd t( ) t 61 4 fci ksi ïï tï« ïºï½ Time development factor (5.4.2.3.2-5) Ï t tinitï¬ï ï¨ ï© 1.9 ksï khcï kfï ktd t( )ï tinitï¨ ï© 0.118ïïïºï½ Creep coefficient (5.4.2.3.2-1) εsh t( ) ks khsï kfï ktd t( )ï 0.48 10 3ïïï¨ ï©ïïºï½ Concrete shrinkage strain (5.4.2.3.3-1) Time from Transfer to Erection: Eccentricity of prestress force with respect to the neutral axis of the gross non-composite beam, positive below the beam neutral axisepg yp ybgï«ï¨ ï©ï 23.772 inïï½ïºï½ Stress in the concrete at the center prestress immediately after transferfcgp Pi 1 Ag epg 2 Ixg ï« ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ï Mg L 2 ï¦ï§ï¨ ï¶ï·ï¸ Ixg yp ybgï«ï¨ ï©ïï« 2.797 ksiïï½ïºï½ fpt max fpi 0.55 fpyïï¬ï ï¨ ï© 186.522 ksiïï½ïºï½ Stress in strands immediately after transfer (5.9.5.4.2c-1) Ïbid Ï td tiï¬ï ï¨ ï© 0.589ï½ïºï½ Creep coefficient at erection due to loading at transfer Ïbif Ï tf tiï¬ï ï¨ ï© 1.282ï½ïºï½ Creep coefficient at final due to loading at transfer εbid εsh td tiïï¨ ï© 1.490 10 4ïï´ï½ïºï½ Concrete shrinkage between transfer and erection Kid 1 1 npi Aps Ag ï 1 Ag epg 2ï Ixg ï« ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ï 1 0.7 Ïbifïï«ï¨ ï©ïï« 0.809ï½ïºï½ Age-adjusted transformed section coefficient (5.9.5.4.2a-2) ÎfpSR εbid Epï Kidï 3.435 ksiïï½ïºï½ Loss due to beam shrinkage (5.9.5.4.2a-1) ÎfpCR npi fcgpï Ïbidï Kidï 7.831 ksiïï½ïºï½ Loss due to creep (5.9.5.4.2b-1) ÎfpR1 fpt KL log 24 tdïï¨ ï© log 24 tiïï¨ ï©ï fpt fpy 0.55ïï¦ï§ï¨ ï¶ï·ï¸ ïï©ïªï« ï¹ïºï» 1 3 ÎfpSR ÎfpCRï«ï¨ ï©ï fpt ïï©ïªï« ï¹ïºï» ï Kidï 1.237 ksiïï½ïºï½ Loss due to relaxation (C5.9.5.4.2c-1 Îfpid ÎfpSR ÎfpCRï« ÎfpR1ï« 12.502 ksiïï½ïºï½
188 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 10. PRESTRESS LOSSES (cont'd) Time from Erection to Final: epc epg 23.772 inïï½ïºï½ Eccentricity of prestress force does not change Ac Agïºï½ Ic Ixgïºï½ Section properties remain unchanged Change in concrete stress at center of prestress due to initial time-dependent losses and superimposed dead load. Deck weight is not included for this design. Îfcd Mfws L 2 ï¦ï§ï¨ ï¶ï·ï¸ Mj L 2 ï¦ï§ï¨ ï¶ï·ï¸ï« Scgpf Îfpid np ï« 2.182 ksiïï½ïºï½ Ïbdf Ï tf tdï¬ï ï¨ ï© 0.858ï½ïºï½ Creep coefficient at final due to loading at erection εbif εsh tf tiïï¨ ï© 3.302 10 4ïï´ï½ïºï½ Concrete shrinkage between transfer and final εbdf εbif εbidï 1.813 10 4ïï´ï½ïºï½ Concrete shrinkage between erection and final Kdf 1 1 npi Aps Ac ï 1 Ac epc 2ï Ic ï« ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ï 1 0.7 Ïbifïï«ï¨ ï©ïï« 0.809ï½ïºï½ Age-adjusted transformed section coefficient remains unchanged ÎfpSD εbdf Epï Kdfï 4.179 ksiïï½ïºï½ Loss due to beam shrinkage ÎfpCD npi fcgpï Ïbif Ïbidïï¨ ï©ï Kdfï np Îfcdï Ïbdfï Kdfïï« 17.168 ksiïï½ïºï½ Loss due to creep ÎfpR2 ÎfpR1 1.237 ksiïï½ïºï½ Loss due to relaxation ÎfpSS 0ïºï½ Loss due to deck shrinkage Îfpdf ÎfpSD ÎfpCDï« ÎfpR2ï« ÎfpSSï« 22.584 ksiïï½ïºï½ Prestress Loss Summary ÎfpES 15.978 ksiïï½ ÎfpES fpj 7.9 %ïï½ ÎfpLT Îfpid Îfpdfï« 35.087 ksiïï½ïºï½ ÎfpLT fpj 17.3 %ïï½ ÎfpTotal ÎfpES ÎfpLTï« 51.065 ksiïï½ïºï½ ÎfpTotal fpj 25.2 %ïï½ Îfp.est 25 %ïï½ fpe fpj ÎfpTotalï 151.4 ksiïï½ïºï½ Final effective prestress CheckFinalPrestress if fpe fpe.maxï£ "OK"ï¬ï "No Good"ï¬ï ï¨ ï© "OK"ï½ïºï½
189 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 11. CONCRETE STRESSES Stresses in the concrete section at release, during handling, and at final service are computed and checked against allowable values appropriate for the stage being considered. Concrete Stresses at Release Stresses at release are computed using the overall beam length as the span because the beam will be supported at its ends in the casting bed after the prestress force is transfered. Define locations for which stresses are to be calculated: xr Lg 0 min Lt Lg Lend Lg ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ max Lt Lg Lend Lg ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ 0.1 0.2 0.3 αhd 0.5ï¦ï§ï¨ ï¶ï·ï¸ T ïïºï½ ir 1 last xrï¨ ï©ï®ï®ïºï½ Functions for computing beam stresses: ftop.r x( ) min x Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Piï 1 Ati ybti ypx x( )ï« Stti ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mgr x( ) Stti ï«ïºï½ Top fiber stress at release fbot.r x( ) min x Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Piï 1 Ati ybti ypx x( )ï« Sbti ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mgr x( ) Sbti ï«ïºï½ Bottom fiber stress at release 0 4 8 12 16 20 24 28 32 36 40 1ï 0 1 2 3 4 Stresses in Concrete at Release (Half Beam) Distance along Beam (ft) St re ss (k si ) ftop.r x( ) ksi fbot.r x( ) ksi fc.all.rel ksi ft.all.rel ksi 0 x ft
190 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 11. CONCRETE STRESSES (cont'd) Compare beam stresses to allowable stresses. ft.all.rel 0.2ï ksiïï½ Allowable tension at release fc.all.rel 3.84 ksiïï½ Allowable compression at release TopRelir ftop.r xrirï¨ ï©ïºï½ TopRelT 0.000 0.148ï 0.192ï 0.097ï 0.002 0.047 0.040 0.062( ) ksiïï½ CheckTopRel if max TopRel( ) fc.all.relï£ï¨ ï© min TopRel( ) ft.all.relï³ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½ BotRelir fbot.r xrirï¨ ï©ïºï½ BotRelT 0.000 2.582 3.241 3.042 2.834 2.738 2.754 2.708( ) ksiïï½ CheckBotRel if max BotRel( ) fc.all.relï£ï¨ ï© min BotRel( ) ft.all.relï³ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½ Concrete Stresses During Lifting and Transportation Stresses in the beam during lifting and transportation may govern over final service limit state stresses due to different support locations, dynamic effects of dead load during shipment and placement, and lateral bending stresses due to rolling during lifting or superelevation of the roadway during shipping. Assume end diaphragms on both ends of the beam. For prestressing effects, compute the effective prestress force using only the losses occuring between transfer and erection (i.e., the âfpid). a h 3.5 ftïï½ïºï½ Maximum distance to lift point from bearing line a' a Lendï« 5.5 ftïï½ïºï½ Distance to lift point from end of beam Pdia max Wia Wsaï¬ï ï¨ ï© 13.2 kipïï½ïºï½ Approximate abutment weight Pm Pj 1 ÎfpES Îfpidï«ï¨ ï© fpj ïï©ïªï« ï¹ïºï» ï 1011.7 kipïï½ïºï½ Effective prestress during lifting and shipping Define locations for which stresses are to be calculated: xe Lg 0 min Lt Lg Lend Lg ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ max Lt Lg Lend Lg ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ a' Lg αhd 0.5ï¦ï§ï¨ ï¶ï·ï¸ T ïïºï½ ie 1 last xeï¨ ï©ï®ï®ïºï½ Compute moment in the girder during lifting with supports at the lift points. Mlift x( ) wg wbarï«ï¨ ï© x2ï 2 Pdia xïï« ï©ïª ï« ï¹ïº ï»ï x a'ï£if Mgr x( ) Mgr a'( ) wg wbarï«ï¨ ï© a'( )2ï 2 ï« Pdia a'ïï« ï©ïª ï« ï¹ïº ï»ï otherwise ïºï½
191 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 11. CONCRETE STRESSES (cont'd) Functions for computing beam stresses: ftop.lift x( ) min x Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Pmï 1 Atf ybtf ypx x( )ï« Sttf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mlift x( ) Sttf ï«ïºï½ Top fiber stress during lifting Top fiber stress during lifting, impact increasing dead loadftop.DIM.inc x( ) min x Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Pmï 1 Atf ybtf ypx x( )ï« Sttf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mlift x( ) Sttf 1 DIMï«( )ïï«ïºï½ Top fiber stress during lifting, impact decreasing dead loadftop.DIM.dec x( ) min x Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Pmï 1 Atf ybtf ypx x( )ï« Sttf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mlift x( ) Sttf 1 DIMï( )ïï«ïºï½ TopLift1ie ftop.lift xeieï¨ ï©ïºï½ TopLift1T 0.000 0.230ï 0.294ï 0.371ï 0.181ï 0.158ï( ) ksiïï½ TopLift2ie ftop.DIM.inc xeieï¨ ï©ïºï½ TopLift2T 0.000 0.236ï 0.302ï 0.393ï 0.065ï 0.035ï( ) ksiïï½ TopLift3ie ftop.DIM.dec xeieï¨ ï©ïºï½ TopLift3T 0.000 0.223ï 0.285ï 0.349ï 0.296ï 0.282ï( ) ksiïï½ fbot.lift x( ) min x Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Pmï 1 Atf ybtf ypx x( )ï« Sbtf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mlift x( ) Sbtf ï«ïºï½ Bottom fiber stress during lifting Bottom fiber stress during lifting, impact increasing dead loadfbot.DIM.inc x( ) min x Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Pmï 1 Atf ybtf ypx x( )ï« Sbtf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mlift x( ) Sbtf 1 DIMï«( )ïï«ïºï½ Bottom fiber stress during lifting, impact decreasing dead loadfbot.DIM.dec x( ) min x Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Pmï 1 Atf ybtf ypx x( )ï« Sbtf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mlift x( ) Sbtf 1 DIMï( )ïï«ïºï½ BotLift1ie fbot.lift xeieï¨ ï©ïºï½ BotLift1T 0.000 2.623 3.292 3.456 3.052 3.005( ) ksiïï½ BotLift2ie fbot.DIM.inc xeieï¨ ï©ïºï½ BotLift2T 0.000 2.637 3.310 3.502 2.808 2.744( ) ksiïï½ BotLift3ie fbot.DIM.dec xeieï¨ ï©ïºï½ BotLift3T 0.000 2.609 3.274 3.410 3.297 3.267( ) ksiïï½ Allowable stresses during handling: fcm fc.erec fcï¨ ï© 7.2 ksiïï½ïºï½ Assumed concrete strength when handling operations begin fc.all.erec 0.6 fcmï 4.32 ksiïï½ïºï½ Allowable compression during lifting and shipping ft.all.erec ft.erec fcmï¨ ï© 0.429ï ksiïï½ïºï½ Allowable tension during lifting and shipping
192 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 11. CONCRETE STRESSES (cont'd) 0 4 8 12 16 20 24 28 32 36 40 0 2 4 Stresses in Concrete During Lifting (Half Beam) Distance along Beam (ft) St re ss (k si ) ftop.lift x( ) ksi ftop.DIM.inc x( ) ksi ftop.DIM.dec x( ) ksi fbot.lift x( ) ksi fbot.DIM.inc x( ) ksi fbot.DIM.dec x( ) ksi fc.all.erec ksi ft.all.erec ksi 0 x ft Compare beam stresses to allowable stresses. TopLiftMaxie max TopLift1ie TopLift2ieï¬ï TopLift3ieï¬ï ï¨ ï©ïºï½ TopLiftMaxT 0 0.223ï 0.285ï 0.349ï 0.065ï 0.035ï( ) ksïï½ TopLiftMinie min TopLift1ie TopLift2ieï¬ï TopLift3ieï¬ï ï¨ ï©ïºï½ TopLiftMinT 0 0.236ï 0.302ï 0.393ï 0.296ï 0.282ï( ) ksïï½ CheckTopLift if max TopLiftMax( ) fc.all.erecï£ï¨ ï© min TopLiftMin( ) ft.all.erecï³ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½ BotLiftMaxie max BotLift1ie BotLift2ieï¬ï BotLift3ieï¬ï ï¨ ï©ïºï½ BotLiftMaxT 0 2.637 3.31 3.502 3.297 3.267( ) ksiïï½ BotLiftMinie min BotLift1ie BotLift2ieï¬ï BotLift3ieï¬ï ï¨ ï©ïºï½ BotLiftMinT 0 2.609 3.274 3.41 2.808 2.744( ) ksiïï½ CheckBotLift if max BotLiftMax( ) fc.all.erecï£ï¨ ï© min BotLiftMin( ) ft.all.erecï³ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½
193 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 11. CONCRETE STRESSES (cont'd) Concrete Stresses at Final Stresses at final are also computed using the design span length. Top flange compression and bottom flange tension are evaluated at the Service I and Service III limit states, respectively. fc.all.ser1 0.4 fcï 3.2 ksiïï½ïºï½ Allowable compression due to effective prestress and dead load (Table 5.9.4.2.1-1) Allowable compression due to effective prestress, permanent load, and transient loads, as well as stresses during shipping and handling (Table 5.9.4.2.1-1)fc.all.ser2 0.6 fcï 4.8 ksiïï½ïºï½ ft.all.ser 0 ksiïï½ Allowable tension (computed previously) Pe fpe Apsï 880.4 kipïï½ïºï½ Effective prestress after all losses Compute stresses at midspan and compare to allowable values. ftop.ser1 x( ) min Lend xï« Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Peï 1 Atf ybtf ypx x( )ï« Sttf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mg x Lendï«ï¨ ï© Stti ï« Mbar x( ) Mfws x( )ï« Mj x( )ï« Sttf ï«ïºï½ ftop.ser2 x( ) min Lend xï« Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Peï 1 Atf ybtf ypx x( )ï« Sttf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mg x Lendï«ï¨ ï© Stti ï« Mbar x( ) Mfws x( )ï« Mj x( )ï« Mll x( )ï« Sttf ï«ïºï½ fbot.ser x( ) min Lend xï« Lt 1ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ Peï 1 Atf ybtf ypx x( )ï« Sbtf ï«ï¦ï§ï¨ ï¶ï·ï¸ ï Mg x Lendï«ï¨ ï© Sbti ï« Mbar x( ) Mfws x( )ï« Mj x( )ï« 0.8 Mll x( )ïï« Sbtf ï«ïºï½ 0 4 8 12 16 20 24 28 32 36 40 0 2 4 6 Stresses in Concrete at Service (Half Beam) Distance along Beam (ft) St re ss (k si ) ftop.ser1 x( ) ksi ftop.ser2 x( ) ksi fbot.ser x( ) ksi ft.all.ser ksi fc.all.ser1 ksi fc.all.ser2 ksi x ft
194 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 11. CONCRETE STRESSES (cont'd) Compare beam stresses to allowable stresses. xs L Lt L 0.1 0.15 0.2 0.25 0.3 0.35 αhd 0.45 0.5ï¦ï§ï¨ ï¶ï·ï¸ T ïïºï½ is 1 last xsï¨ ï©ï®ï®ïºï½ TopSer1is ftop.ser1 xsisï¨ ï©ïºï½ TopSer1T 0.046ï 0.101 0.195 0.272 0.330 0.370 0.393 0.397 0.398 0.400( ) ksiïï½ TopSer2is ftop.ser2 xsisï¨ ï©ïºï½ TopSer2T 0.075 0.415 0.636 0.820 0.966 1.074 1.148 1.191 1.211 1.212( ) ksiïï½ CheckCompSerI if max TopSer1( ) fc.all.ser1ï£ï¨ ï© max TopSer2( ) fc.all.ser2ï£ï¨ ï©ï "OK"ï¬ï "No Good"ï¬ï ï©ï« ï¹ï» "OK"ï½ïºï½ BotSeris fbot.ser xsisï¨ ï©ïºï½ BotSerT 2.218 1.581 1.168 0.825 0.554 0.355 0.221 0.146 0.112 0.109( ) ksiïï½ CheckTenSerIII if min BotSer( ) ft.all.serï³ "OK"ï¬ï "No Good"ï¬ï ï¨ ï© "OK"ï½ïºï½ 12. FLEXURAL STRENGTH Verify flexural resistance at the Strength Limit State. Compute the factored moment at midspan due to the Strength I load combination, then compare it to the factored resistance calculated in accordance with AASHTO LRFD 5.7.3. MDC x( ) Mg x( ) Mbar x( )ï« Mj x( )ï«ïºï½ Self weight of components MDW x( ) Mfws x( )ïºï½ Weight of future wearing surface MLL x( ) Mll x( )ïºï½ Live load MStrI x( ) 1.25 MDC x( )ï 1.5 MDW x( )ïï« 1.75 MLL x( )ïï«ïºï½ Factored design moment For minimum reinforcement check, per 5.7.3.3.2 fcpe Pe 1 Ag ycgp Sbg ï«ï¦ï§ï¨ ï¶ï·ï¸ ï 3.677 ksiïï½ïºï½ Concrete compression at extreme fiber due to effective prestress Mcr fr.cm fcpeï«ï¨ ï©ï Sbgï 2825 kip ftïïï½ïºï½ Cracking moment (5.7.3.3.2-1) Mu x( ) max MStrI x( ) min 1.33 MStrI x( )ï 1.2 Mcrïï¬ï ï¨ ï©ï¬ï ï¨ ï©ïºï½ Design moment
195 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 12. FLEXURAL STRENGTH (cont'd) Compute factored flexural resistance. β1 max 0.65 0.85 0.05 fc ksi 4ïï¦ï§ï¨ ï¶ï·ï¸ïïï¬ï ï©ïªï« ï¹ïºï» 0.65ï½ïºï½ Stress block factor (5.7.2.2) k 2 1.04 fpy fpu ïï¦ï§ï¨ ï¶ï·ï¸ ï 0.28ï½ïºï½ Tendon type factor (5.7.3.1.1-2) Distance from compression fiber to prestress centroiddp x( ) h ypx x Lendï«ï¨ ï©ïïºï½ dp X( ) 37.421 inïï½ hf d7 8 inïï½ïºï½ Structural flange thickness btaper b6 b5ï 2 19.5 inïï½ïºï½ Average width of taper at bottom of flange htaper d5 3 inïï½ïºï½ Depth of taper at bottom of flange a x( ) Aps fpuï 0.85 fcï bfï k β1 Apsï fpu dp x( ) ï¦ï§ï¨ ï¶ï·ï¸ ïï« ïºï½ a X( ) 2.509 inïï½ Depth of equivalent stress block for rectangular section c x( ) a x( ) β1ïºï½ c X( ) 3.861 inïï½ Neutral axis location CheckTC if c X( ) dp X( ) .003 .003 .005ï« ï¦ï§ï¨ ï¶ï·ï¸ï£ "OK"ï¬ï "NG"ï¬ï ï©ïªï« ï¹ïºï» "OK"ï½ïºï½ Tension-controlled section check (midspan) Resistance factor for prestressed concrete (5.5.4.2)Ïf min 1.0 max 0.75 0.583 0.25 dp X( ) c X( ) 1ïï¦ï§ï¨ ï¶ï·ï¸ïï«ï¬ï ï©ïªï« ï¹ïºï»ï¬ï ï©ïªï« ï¹ïºï» 1.00ï½ïºï½ fps fpu 1 k c X( ) dp X( ) ïïï¦ï§ï¨ ï¶ï·ï¸ ï 262.2 ksiïï½ïºï½ Average stress in the prestressing steel (5.7.3.1.1-1) Ld 1.6 ksi fps 2 3 fpeïïï¦ï§ï¨ ï¶ï·ï¸ï dpsï 10.75 ftïï½ïºï½ Bonded strand devlepment length (5.11.4.2-1) fpx x( ) fpe x Lendï«ï¨ ï©ï Lt x Lt Lendïï£if fpe x Lendï«ï¨ ï© Ltï Ld Ltï fps fpeïï¨ ï©ïï« Lt Lendï xï¼ Ld Lendïï£if fps otherwise ïºï½ Stress in prestressing steel along the length for bonded strand (5.11.4.2) Mr x( ) Ïf Aps fpx x( )ï dp x( ) a x( )2ï ï¦ï§ï¨ ï¶ï·ï¸ï ï©ïªï« ï¹ïºï»ïïºï½ Flexure resistance along the length
196 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 12. FLEXURAL STRENGTH (cont'd) xmom L 0.01 Lt Lendï L Ld Lendï L αhd 0.5ï¦ï§ï¨ ï¶ï·ï¸ T ïïºï½ imom 1 last xmomï¨ ï©ï®ï®ïºï½ Mrximom Mr xmomimomï¨ ï©ïºï½ Muximom Mu xmomimomï¨ ï©ïºï½ DCmom Mux Mrx ïºï½ max DCmomï¨ ï© 0.769ï½ Demand-Capacity ratio for moment CheckMom if max DCmomï¨ ï© 1.0ï£ "OK"ï¬ï "No Good"ï¬ï ï¨ ï© "OK"ï½ïºï½ Flexure resistance check 0 4 8 12 16 20 24 28 32 36 40 0 1000 2000 3000 4000 Design Moment and Flexure Resistance (Half Beam) Distance along Beam (ft) M om en t ( ki p· ft) MStrI x( ) kip ftï 1.2 Mcrï kip ftï 1.33 MStrI x( )ï kip ftï Mu x( ) kip ftï Mr x( ) kip ftï x ft
197 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 13. SHEAR STRENGTH Shear Resistance Compute the factored shear at the critical shear section and at tenth points along the span due to the Strength I load combination, then compare it to the factored resistance calculated in accordance with AASHTO LRFD 5.8. VDC x( ) Vg x( ) Vbar x( )ï« Vj x( )ï«ïºï½ Self weight of components VDW x( ) Vfws x( )ïºï½ Weight of future wearing surface VLL x( ) Vll x( )ïºï½ Live load Vu x( ) 1.25 VDC x( )ï 1.5 VDW x( )ïï« 1.75 VLL x( )ïï«ïºï½ Factored design shear Resistance factor for shear in normal weight concrete (AASHTO LRFD 5.5.4.2)Ïv 0.90ïºï½ dend h ypx Lendï¨ ï©ï 32.368 inïï½ïºï½ Depth to steel centroid at bearing dv min 0.9 dendï 0.72 hïï¬ï ï¨ ï© 29.132 inïï½ïºï½ Effective shear depth lower limit at end Vp x( ) Pe slopecgpï x Lendï« Lt ï x Lt Lendïï£if Pe slopecgpï Lt Lendï xï¼ Î±hd Lïï£if 0 otherwise ïºï½ Vertical component of effective prestress force bv b3 6 inïï½ïºï½ Web thickness Shear stress on concrete (5.8.2.9-1) vu x( ) Vu x( ) Ïv Vp x( )ïï Ïv bvï dvïïºï½ Mushr x( ) max MStrI x( ) Vu x( ) Vp x( )ï dvïï¬ï ï¨ ï©ïºï½ Factored moment for shear Stress in prestressing steel due to locked-in strain after casting concretefpo 0.7 fpuï 189 ksiïï½ïºï½ Steel strain at the centroid of the prestressing steelεs x( ) max 0.4ï 10 3ïï Mu x( ) dv Vu x( ) Vp x( )ïï« Aps fpoïï Ep Apsï ï¬ï ï¦ï§ ï§ ï§ï¨ ï¶ï· ï· ï·ï¸ ïºï½ β x( ) 4.8 1 750 εs x( )ïï«ïºï½ Shear resistance parameter θ x( ) 29 3500 εs x( )ïï«ï¨ ï© degïïºï½ Principal compressive stress angle Vc x( ) 0.0316 ksiï β x( )ï fc ksi ï bvï dvïïºï½ Concrete contribution to total shear resistance
198 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 13. SHEAR STRENGTH (cont'd) α 90 degïïºï½ Angle of inclination of transverse reinforcement Transverse reinforcement area and spacing providedAv 1.02 0.62 0.62 0.62 0.31( ) T in2ïïºï½ sv 3 6 6 12 12( )T inïïºï½ xv 0 0.25 hï 1.5 hï 0.3 Lï 0.5 Lï 0.6 Lï( )Tïºï½ xvT 0 0.875 5.25 21 35 42( ) ftïï½ Avs x( ) out Avi svi ï¬ xvi xï£ xvi 1ï«ï£if i 1 last Avï¨ ï©ï®ï®ïfor out ïºï½ . Vs x( ) Avs x( ) fyï dvï cot θ x( )( ) cot α( )ï«( )ï sin α( )ïïºï½ Steel contribution to total shear resistance Vr x( ) Ïv Vc x( ) Vs x( )ï« Vp x( )ï«ï¨ ï©ïïºï½ Factored shear resistance xshr outi i 0.5 Lï 100 ïï¬ i 1 100ï®ï®ïfor out ïºï½ ishr 1 last xshrï¨ ï©ï®ï®ïºï½ Vuxishr Vu xshrishrï¨ ï©ïºï½ Vrxishr Vr xshrishrï¨ ï©ïºï½ DCshr Vux Vrx ïºï½ max DCshrï¨ ï© 0.787ï½ CheckShear if max DCshrï¨ ï© 1.0ï£ "OK"ï¬ï "No Good"ï¬ï ï¨ ï© "OK"ï½ïºï½ Shear resistance check 0 4 8 12 16 20 24 28 32 36 40 0 100 200 300 400 Design Shear and Resistance (Half Beam) Distance along Beam (ft) Sh ea r ( ki ps ) Vu x( ) kip Vr x( ) kip x ft
199 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 13. SHEAR STRENGTH (cont'd) Longitudinal Reinforcement Al.req x( ) a1 MStrI x( ) Ïf fpx x( )ï dp x( ) a x( )2ï ï¦ï§ï¨ ï¶ï·ï¸ï ï¬ a2 Vu x( ) Ïv 0.5 Vs x( )ïï Vp x( )ï ï¦ï§ï¨ ï¶ï·ï¸ cot θ x( )( )ï fpx x( ) ï¬ a3 Mushr x( ) dv Ïfï Vu x( ) Ïv Vp x( )ï 0.5 Vs x( )ïï ï¦ï§ï¨ ï¶ï·ï¸ cot θ x( )( )ïï« fpx x( ) ï¬ min a1 a2ï¬ï ( ) x dv 5 inïï«ï£if min a1 a3ï¬ï ( ) otherwise ïºï½ Longitudinal reinforcement required for shear (5.8.3.5) As.add 0.40 in 2ïïºï½ Ld.add 18.67 ftïïºï½ Additional longitudinal steel and developed length from end of beam Al.prov x( ) if x Ld.add Lendïï¼ As.addï¬ï 0ï¬ï ï¨ ï© Ap Nsï x Lendï«Ldï x Ld Lendïï£if Ap Nsï Ld Lendï xï¼ yh.brg 0.5 hïï slopecgp 0.5 Nhï 1ï 2 ï¦ï§ï¨ ï¶ï·ï¸ 2 inï( )ï cot slopecgpï¨ ï©ïï«ï£if Ap Nh Nsï«ï¨ ï©ï otherwise ï«ïºï½ 0 4 8 12 16 20 24 28 32 36 40 0 2 4 6 Longitudinal Reinforcement Required and Provided (Half Beam) Distance along Beam (ft) St ee l A re a (in 2) Al.req x( ) in2 Al.prov x( ) in2 x ft Al.reqishr Al.req xshrishrï¨ ï©ïºï½ Al.provishr Al.prov xshrishrï¨ ï©ïºï½ DClong Al.req Al.prov ïºï½ max DClongï¨ ï© 0.93ï½ CheckLong if max DClongï¨ ï© 1.0ï£ "OK"ï¬ï "No Good"ï¬ï ï¨ ï© "OK"ï½ïºï½ Longitudinal reinforcement check
200 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 14. SPLITTING RESISTANCE Splitting Resistance Checking splitting resistance provided by first zone of transverse reinforcement defined in the previous section for shear design. As Av1 xv2 ï sv1 3.57 in2ïï½ïºï½ fs 20 ksiïïºï½ Limiting stress in steel for crack control (5.10.10.1) Pr fs Asï 71.4 kipïï½ïºï½ Splitting resistance provided (5.10.10.1-1) Pr.min 0.04 Pjï 47.1 kipïï½ïºï½ Minimum splitting resistance required CheckSplit if Pr Pr.minï³ "OK"ï¬ï "No Good"ï¬ï ï¨ ï© "OK"ï½ïºï½ Splitting resistance check 15. CAMBER AND DEFLECTIONS Îps Piï Eci Ixgï ycgp Lg 2ï 8 ybg yp.brgï«ï¨ ï© Î±hd Lï Lendï«ï¨ ï©2ï 6 ï ï©ïª ï« ï¹ïº ï»ï 2.131 inïï½ïºï½ Deflection due to prestress at release Îgr 5ï384 wg Lg 4ï Eci Ixgï ï 0.917ï inïï½ïºï½ Deflection due to self-weight at release Îbar 5ï384 wbar Lg 4ï Ec Ixgï ï 0.263ï inïï½ïºï½ Deflection due to barrier weight 2Îj 5ï384 wj L 4ï Ec Ixgï ï if BeamLoc 0= 1ï¬ï 0.5ï¬ï ( )ï 0.013ï inïï½ïºï½ Deflection due to longitudinal joint Îfws 5ï384 wfws L 4ï Ec Ixgï ï if BeamLoc 0= 1ï¬ï S Wbï S ï¬ï ï¦ï§ï¨ ï¶ï·ï¸ï 0.079ï inïï½ïºï½ Deflection due to future wearing surface tbar 20ïºï½ Age at which barrier is assumed to be cast T ti 7 14 21 28 60 120 240 âï¨ ï©Tïºï½ Concrete ages at which camber is computed
201 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 15. CAMBER AND DEFLECTIONS (cont'd) Îcr1 t( ) Ï t tiï tiï¬ï ï¨ ï© Îgr Îpsï«ï¨ ï©ïºï½ Îcr2 t( ) Ï t tiï tiï¬ï ï¨ ï© Ï tbar tiï tiï¬ï ï¨ ï©ïï¨ ï© Îgr Îpsï«ï¨ ï©ï Ï t tbarï tbarï¬ï ï¨ ï© Îbarïï«ïºï½ Îcr3 t( ) Ï t tiï tiï¬ï ï¨ ï© Ï td tiï tiï¬ï ï¨ ï©ïï¨ ï© Îgr Îpsï«ï¨ ï©ï Ï t tbarï tbarï¬ï ï¨ ï© Ï td tbarï tbarï¬ï ï¨ ï©ïï¨ ï© Îbarïï« Ï t tdï tdï¬ï ï¨ ï© Îjï¨ ï©ïï« ï®ï®ï®ïºï½ Îcr t( ) Îcr1 t( ) t tbarï£if Îcr1 tbarï¨ ï© Îcr2 t( )ï« tbar tï¼ tdï£if Îcr1 tbarï¨ ï© Îcr2 tdï¨ ï©ï« Îcr3 t( )ï« t tdï¾if ïºï½ Defl t( ) Îgr Îpsï«ï¨ ï© Îcr1 t( )ï« t tbarï£if Îgr Îpsï«ï¨ ï© Îcr1 tbarï¨ ï©ï« Îbarï« Îcr2 t( )ï« tbar tï¼ tdï£if Îgr Îpsï«ï¨ ï© Îcr1 tbarï¨ ï©ï« Îbarï« Îcr2 tdï¨ ï©ï« Îjï« Îcr3 t( )ï« t tdï¾if ïºï½ C outj Defl Tjï¨ ï©ï¬ j 1 last T( )ï®ï®ïfor out ïºï½ CT 1.213 1.439 1.632 1.506 1.581 1.78 1.955 2.081 2.247( ) inïï½ 0 20 40 60 0 1 2 3 60-Day Deflection at Midspan Age of Concrete (days) D ef le ct io n (in ) Îcr t( ) in Defl t( ) in t 0 500 1000 1500 2000 0 1 2 3 Long-term Deflection at Midspan Age of Concrete (days) D ef le ct io n (in ) Îcr t( ) in Defl t( ) in t
202 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 16. NEGATIVE MOMENT FLEXURAL STRENGTH Compute the factored moment to be resisted across the interior pier and determine the required reinforcing steel to be fully developed in the top flange. Negative Live Load Moment Compute the negative moment over the interior support due to the design live load load, in accordance with AASHTO LRFD 3.6.1.3.1. Live Load Truck and Truck Train Moment Calculations Maximum negative moment due to a single truckmin Mtruckï¨ ï© 889ï kip ftïïï½ Maximum negative moment due to two trucks in a single lanemin Mtrainï¨ ï© 1650ï kip ftïïï½ Negative moment due to lane load on adjacent spansMneg.lane wlaneï L2ï 2 1568ï kip ftïïï½ïºï½ Mneg.truck Mneg.lane 1 IMï«( ) min Mtruckï¨ ï©ïï« 2750ï kip ftïïï½ïºï½ Live load negative moment for single truck Live load negative moment for two trucks in a single laneMneg.train 0.9 Mneg.lane 1 IMï«( ) min Mtrainï¨ ï©ïï«ï©ï« ï¹ï»ï 3387ï kip ftïïï½ïºï½ Design negative live load moment, per design laneMHL93.neg min Mneg.truck Mneg.trainï¬ï ï¨ ï© 3387ï kip ftïïï½ïºï½ Design negative live load moment at interior beamMll.neg.i MHL93.neg gmintï 2144ï kip ftïïï½ïºï½ Design negative live load moment at exterior beamMll.neg.e MHL93.neg gmextï 2233ï kip ftïïï½ïºï½ MLL.neg if BeamLoc 1= Mll.neg.eï¬ï Mll.neg.iï¬ï ï¨ ï© 2233ï kip ftïïï½ïºï½ Design negative live load moment Factored Negative Design Moment Dead load applied to the continuity section at interior supports is limited to the future overlay. Superimposed dead load resisted by continuity sectionMDW.neg wfwsï L2ï 2 487ï kip ftïïï½ïºï½ Mu.neg.StrI 1.5 MDW.negï 1.75 MLL.negïï« 4638ï kip ftïïï½ïºï½ Strength Limit State Mu.neg.StrI 1.0 MDW.negï 1.0 MLL.negïï« 2720ï kip ftïïï½ïºï½ Service Limit State
203 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 16. NEGATIVE MOMENT FLEXURAL STRENGTH (cont'd) Reinforcing Steel Requirement in the Top Flange for Strength Reduction factor for strength in tension- controlled reinforced concrete (5.5.4.2)Ïf 0.90ïºï½ bc b1 26 inïï½ïºï½ Width of compression block at bottom flange Distance to centroid of negative moment steel, taken at mid-depth of top flangednms h tsacï 0.5 tflange tsacïï¨ ï©ïï 37 inïï½ïºï½ Factored load, in terms of stress in concrete at depth of steel, for computing steel requirement Ru Mu.neg.StrI Ïf bcï dnms2ï 1.019 ksiïï½ïºï½ m fy 0.85 fcï 8.824ï½ïºï½ Steel-to-concrete strength ratio Ïreq 1m 1 1 2 mï Ruï fy ïïï¦ï§ï¨ ï¶ï·ï¸ ï 0.0185ï½ïºï½ Required negative moment steel ratio Anms.req Ïreq bcï dnmsï 17.787 in2ïï½ïºï½ Required negative moment steel in top flange Full-length longitudinal reinforcement to be made continuous across jointAs.long.t 2.0 in 2ïïºï½ As.long.b 2.0 in2ïïºï½ Additional negative moment reinforcing bar areaAbar 0.44 in 2ïïºï½ Additional reinforcement area required in the top mat (2/3 of total)Anms.t 2 3 Anms.reqï As.long.tï 9.858 in2ïï½ïºï½ nbar.t ceil Anms.t Abar ï¦ï§ï¨ ï¶ï·ï¸ 23ï½ïºï½ Additional bars required in the top mat Additional reinforcement area required in the bottom matAnms.b 1 3 Anms.reqï As.long.bï 3.929 in2ïï½ïºï½ nbar.b ceil Anms.b Abar ï¦ï§ï¨ ï¶ï·ï¸ 9ï½ïºï½ Additional bars required in the top mat sbar.top S Wjï 6 inïï nbar.t 1ï 3.788 inïï½ïºï½ Spacing of bars in top mat As.nms nbar.t nbar.bï«ï¨ ï© Abarï As.long.tï« As.long.bï« 18.08 in2ïï½ïºï½ Total reinforcing steel provided over pier a As.nms fyï 0.85 fcï bcï 6.136 inïï½ïºï½ Depth of compression block Mr.neg Ïf As.nmsï fyï dnms a2ï ï¦ï§ï¨ ï¶ï·ï¸ï 2761 kip ftïïï½ïºï½ Factored flexural resistance at interior pier DCneg.mom Mu.neg.StrI Mr.neg 0.985ï½ïºï½ CheckNegMom if DCneg.mom 1.0ï£ "OK"ï¬ï "No Good"ï¬ï ï¨ ï© "OK"ï½ïºï½ Negative flexure resistance check
204 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ABC SAMPLE CALCULATION â 3a Precast Pier Design for ABC (70â Span Straddle Bent)
205 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT PRECAST PIER DESIGN FOR ABC (70' SPAN STRADDLE BENT) Nomenclature FNofBm Total Numberï ofï Beamsï inï Forwardï Spanï= BNofBm Total Numberï ofï Beamsï inï Backwardï Spanï= FSpan Forward Spanï Lengthï= BSpan Backward Spanï Lengthï= FDeckW Out toï Outï Forwardï Spanï Deckï Widthï= BDeckW Out toï Outï Backwardï Spanï Deckï Widthï= FBmAg Forward Spanï Beamï Xï Sectionalï Areaï= BBmAg Backward Spanï Beamï Xï Sectionalï Areaï= FBmFlange Forward Spanï Beamï Topï Flangeï Widthï= BBmFlange Backward Spanï Beamï Topï Flangeï Widthï= FHaunch Forward Spanï Haunchï Thicknessï= BHaunch Backward Spanï Haunchï Thicknessï= FBmD Forward Spanï Beamï Depthï orï Heightï= BBmD Backward Spanï Beamï Depthï orï Heightï= FBmIg Forward Spanï Beamï Momentï ofï Inertiaï= BBmIg Backward Spanï Beamï Momentï ofï Inertiaï= yFt Forward Spanï Beamï Topï Distanceï fromï cgï= yBt Backward Spanï Beamï Topï Distanceï fromï cgï= NofCol Number ofï Columnsï perï Bentsï=SlabTh Slab Thicknessï= NofDs Number ofï Drilledï Shaftï perï Bentsï=RailWt Railing Weightï= wCol Width ofï Columnï Sectionï=RailH Railing Heightï= bCol Breadth ofï Columnï Sectionï=RailW Rail Baseï Widthï= DsDia Drilled Shaftï Diameterï=LeftOH Left Overhangï Distanceï= HCol Height ofï Columnï=RightOH Right Overhangï Distanceï= wEarWall Width ofï Earï Wallï=DeckW Out toï Outï Deckï Widthï atï Bentï= hEarWall Height ofï Earï Wallï=RoadW Roadway Widthï= tEarWall Thickness ofï Earï Wallï=BrgTh Bearing Padï Thicknessï Bearing Seatï Thicknessïï«= tSWalk Thickness ofï Sideï Walkï=NofLane Number ofï Lanesï= bSWalk Breadth ofï Sideï Walkï=wCap Cap Widthï= BmMat Beam Materialï eitherï Steelï orï Concreteï=hCap Cap Depthï= hbS Bottom Solidï Heightï atï Foamï=CapL Cap Lengthï= htS Top Solidï Heightï atï Foamï=wFoam Width ofï Foamï forï Blockoutï= γst Unit Weightï ofï Steelï=hFoam heigth ofï Foamï forï Blockoutï= γc wc Unit Weightï ofï Concreteï=ï¬ï LFoam Length foï Foamï forï Blockoutï=
206 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT SlabDCInt Dead Loadï forï Slabï perï Interiorï Beamï= SlabDCExt Dead Loadï forï Slabï perï Exteriorï Beamï= BeamDC Self Weightï ofï Beamï= HaunchDC Dead Loadï ofï Haunchï Concreteï perï Beamï= RailDC Weight ofï Railï perï Beamï= FSuperDCInt Half ofï Forwardï Spanï Superï Structureï Deadï Loadï Componentï perï Interiorï Beamï= FSuperDCExt Half ofï Forwardï Spanï Superï Structureï Deadï Loadï Componentï perï Exteriorï Beamï= FSuperDW Half ofï Forwardï Spanï Overlayï Deadï Loadï Componentï perï Beamï= BSuperDCInt Half ofï Backwardï Spanï Superï Structureï Deadï Loadï Componentï perï Interiorï Beamï= BSuperDCExt Half ofï Backwardï Spanï Superï Structureï Deadï Loadï Componentï perï Exteriorï Beamï= BSuperDW Half ofï Backwardï Spanï Overlayï Deadï Loadï Componentï perï Beamï= TorsionDCInt DeadLoad Torsionï inï aï Capï dueï toï differenceï inï Forwardï andï Backwardï spanï lengthï perï Interiorï Beamï= TorsionDCExt DeadLoad Torsionï inï aï Capï dueï toï differenceï inï Forwardï andï Backwardï spanï lengthï perï Exteriorï Beamï= TorsionDW DW Torsionï inï aï Capï dueï toï differenceï inï Forwardï andï Backwardï spanï lengthï perï Beamï= DiapWt Weight ofï Diaphragmï= tBrgSeat Thickness ofï Bearingï Seatï= bBrgSeat Breadth ofï Bearingï Seatï=
207 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Note: Use of Light-Weight-Concrete (LWC) may be considered to reduce the weight of the pier cap instead of styrofoam blockouts.
208 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT FORWARD SPAN PARAMETER INPUT: FNofBm 12ïºï½ FSpan 70 ftïïºï½ FDeckW 283 6 ftïïºï½ FBmAg 29.1 in2ïïºï½ FBmFlange 10.5 inïïºï½ yFt 14.85 inïïºï½FHaunch 0 inïïºï½ FBmD 29.7 inïïºï½ FBmIg 3990 in4ïïºï½ BACKWARD SPAN PARAMETER INPUT: BNofBm 12ïºï½ BSpan 70 ftïïºï½ BDeckW 283 6 ftïïºï½ BBmAg 29.1 in2ïïºï½ BBmFlange 10.5 inïïºï½ yBt 14.85 inïïºï½BHaunch 0 inïïºï½ BBmD 29.7 inïïºï½ BBmIg 3990 in4ïïºï½ COMMON BRIDGE PARAMETER INPUT: Intermediate Bent between Forward and Backward span Parameters SlabTh 9 inïïºï½ Overlay 25 psfïïºï½ θ 0 degïïºï½ DeckOH 1.75 ftïïºï½ BrgTh 3.5 inïïºï½ RailWt 0.43 klfïïºï½ RailW 19 inïïºï½ RailH 34.0 inïïºï½ tBrgSeat 0 inïïºï½ bBrgSeat 0 ftïïºï½ DeckW 283 6 ftïïºï½ NofLane 3ïºï½ m 0.85ïºï½ wc 0.150 kcfïïºï½ f'c 5 ksiïïºï½ Cap( ) wCap 4.5 ftïïºï½ hCap 5 ftïïºï½ CapL 47 ftïïºï½ NofDs 2ïºï½ DsDia 6 ftïïºï½ wCol 4 ftïïºï½ bCol 4 ftïïºï½ NofCol 2ïºï½ HCol 22.00 ftïïºï½ f'cs 4 ksiïïºï½ Slab( ) γc 0.150 kcfïïºï½ ebrg 13 inïïºï½ NofBm 12ïºï½ Sta 0.25 ftincrïïºï½ DiapWt 0.2 kipïïºï½ wEarWall 0 ftïïºï½ hEarWall 0 ftïïºï½ tEarWall 0 inïïºï½ IM 0.33ïºï½ BmMat Steelïºï½ LFoam 35 ftïïºï½ wFoam 14 inïïºï½ hFoam 31 inïïºï½ hbS 15 inïïºï½ (Bottom Solid Depth of Section) Es 29000 ksiïïºï½ γst 490 pcfïïºï½ steel( ) Modulus of elasticity of Concrete: E fcï¨ ï© 33000 wcï¨ ï©1.5ï fc ksiïïïºï½ (AASHTO LRFD EQ 5.4.2.4-1 for K1 = 1) Eslab E f'csï¨ ï©ïºï½ Eslab 3834.254 ksiïï½ Ecap E f'cï¨ ï©ïºï½ Ecap 4286.826 ksiïï½ Modulus of Beam or Girder: Input Beam Material, BmMat = Steel or Concrete Ebeam if BmMat Steel= Esï¬ï E f'cï¨ ï©ï¬ï ï¨ ï©ïºï½ Ebeam 29000 ksiïï½
209 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 1. BENT CAP LOADING DEAD LOAD FROM SUPERSTRUCTURE: The permanent dead load components (DC) consist of slab, rail, sidewalk, haunch weight and beam self weight. Slab dead weight components will be distributed to each beam by slab tributary width between beams. Interior Beam tributary width (IntBmTriW) is taken as the average of consecutive beam spacing for a particular interior beam. Exterior Beam tributary width (ExtBmTriW) is taken as half of beam spacing plus the overhang distance. Rail, sidewalk dead load components and future wearing surface weight components (DW) can be distributed evenly among each beam. Half of DC and DW components from forward span and backward span comprise the total superstructure load or dead load reaction per beam on the pier cap or the bent cap. FORWARD SPAN SUPERSTRUCTURE DEAD LOAD: consists of 12 W30x99 Beams 12 beams were spaced 4.5' and 3'-4" alternately in forward span. For beam spacing see Typical Section Details sheet FBmSpa1 4.5 ftïïºï½ FBmSpa2 10 3 ftïïºï½ FIntBmTriW FBmSpa1 2 FBmSpa2 2 ï«ïºï½ FIntBmTriW 3.917 ftïï½ FExtBmTriW FBmSpa1 2 DeckOHï«ïºï½ FExtBmTriW 4 ftïï½ RoadW 0.25 FDeckW 3 DeckWïï«( )ï 2 RailWïïïºï½ RoadW 44 ftïï½ SlabDCInt γc FIntBmTriWï SlabThï FSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ SlabDCInt 15.422 kip beam ïï½ SlabDCExt γc FExtBmTriWï SlabThï FSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ SlabDCExt 15.75 kip beam ïï½ BeamDC γst FBmAgï FSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ BeamDC 3.466 kip beam ïï½ HaunchDC γc FHaunchï FBmFlangeï FSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ HaunchDC 0 kip beam ïï½ NOTE: Permanent loads such as the weight of the Rail (Barrier), Future wearing surface may be distributed uniformly among all beams if following conditions are met. Apply for live load distribution factors too. AASHTO LRFD 4.6.2.2.1 1. Width of deck is constant 2. Number of Beams >= 4 beams 3. Beams are parallel and have approximately same stiffness 4. The Roadway part of the overhang, de<= 3ft 5. Curvature in plan is < 4o 6. Bridge cross-section is consistent with one of the x-section shown in AASHTO LRFD TABLE 4.6.2.2.1-1 RailDC 2 RailWtï FNofBm FSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ RailDC 2.508 kip beam ïï½ OverlayDW RoadW Overlayï FNofBm FSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ OverlayDW 3.208 kip beam ïï½
210 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Forward Span Superstructure DC & DW per Interior and Exterior Beam: FSuperDCInt RailDC BeamDCï« SlabDCIntï« HaunchDCï« DiapWtï«ïºï½ FSuperDCInt 21.596 kip beam ïï½ FSuperDCExt RailDC BeamDCï« SlabDCExtï« HaunchDCï« 0.5 DiapWtïï«ïºï½ FSuperDCExt 21.824 kip beam ïï½ FSuperDW OverlayDWïºï½ FSuperDW 3.208 kip beam ïï½ BACKWARD SPAN SUPERSTRUCTURE DEAD LOAD: consists of 12 W30x99 beams 12 beams were spaced 4.5' and 3'-4" alternately in backward span. For beam spacing see Typical Section Details sheet BBmSpa1 4.5 ftïïºï½ BBmSpa2 10 3 ftïïºï½ BIntBmTriW BBmSpa1 2 BBmSpa2 2 ï«ïºï½ BIntBmTriW 3.917 ftïï½ BExtBmTriW BBmSpa1 2 DeckOHï«ïºï½ BExtBmTriW 4 ftïï½ RoadW 0.25 BDeckW 3 DeckWïï«( )ï 2 RailWïïïºï½ RoadW 44 ftïï½ SlabDCInt γc BIntBmTriWï SlabThï BSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ SlabDCInt 15.422 kip beam ïï½ SlabDCExt γc BExtBmTriWï SlabThï BSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ SlabDCExt 15.75 kip beam ïï½ BeamDC γst BBmAgï BSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ BeamDC 3.466 kip beam ïï½ HaunchDC γc BHaunchï BBmFlangeï BSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ HaunchDC 0 kip beam ïï½ RailDC 2 RailWtï BNofBm BSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ RailDC 2.508 kip beam ïï½ OverlayDW RoadW Overlayï BNofBm BSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ OverlayDW 3.208 kip beam ïï½ Total Backward Span Superstructure DC & DW per Interior and Exterior Beam: BSuperDCInt RailDC BeamDCï« SlabDCIntï« HaunchDCï« DiapWtï«ïºï½ BSuperDCInt 21.596 kip beam ïï½ BSuperDCExt RailDC BeamDCï« SlabDCExtï« HaunchDCï« 0.5 DiapWtïï«ïºï½ BSuperDCExt 21.824 kip beam ïï½ BSuperDW OverlayDWïºï½ BSuperDW 3.208 kip beam ïï½
211 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Total Superstructure DC & DW per Beam on Bent Cap: SuperDCInt FSuperDCInt BSuperDCIntï«ïºï½ SuperDCInt 43.192 kip beam ïï½ SuperDCExt FSuperDCExt BSuperDCExtï«ïºï½ SuperDCExt 43.648 kip beam ïï½ SuperDW FSuperDW BSuperDWï«ïºï½ SuperDW 6.417 kip beam ïï½ TorsionDCInt max FSuperDCInt BSuperDCIntï¬ï ï¨ ï© min FSuperDCInt BSuperDCIntï¬ï ï¨ ï©ïï¨ ï© ebrgïïºï½ TorsionDCInt 0 kftbeamïï½ TorsionDCExt max FSuperDCExt BSuperDCExtï¬ï ï¨ ï© min FSuperDCExt BSuperDCExtï¬ï ï¨ ï©ïï¨ ï© ebrgïïºï½ TorsionDCExt 0 kftbeamïï½ TorsionDW max FSuperDW BSuperDWï¬ï ( ) min FSuperDW BSuperDWï¬ï ( )ï( ) ebrgïïºï½ TorsionDW 0 kft beam ïï½ CAP, EAR WALL & BEARING SEAT WEIGHT: The Bent cap has two sections along the length. One is a solid rectangular section 6ft from the both ends. The middle section is made hollow by placing foam blockouts in two sides of mid section as can be seen in the typical section and pier elevation figure. CapDC1 is the weight of the solid section and CapDC2 is the weight of the hollow section. CapDC1 wCap hCapï γcïïºï½ Applicable forï 0 ftï CapLï£ 6 ftïï£( )ï 41 ftï CapLï£ 47 ftïï£( )ï¬ï CapDC1 3.375 kipftïï½ CapDC2 wCap hCapï 2 wFoamï hFoamïï( ) γcïïºï½ Applicable forï 6 ftï CapLï£ 41 ftïï£( )ï CapDC2 2.471 kipftïï½ EarWallDC wEarWall hEarWallï tEarWallï( ) γcïïºï½ EarWallDC 0 kipïï½ BrgSeatDC tBrgSeat bBrgSeatï wCap( )ï γcïïºï½ BrgSeatDC 0 kipbeamïï½ Distribution Factor RESULTS OF DISTRIBUTION FACTORS: Forward Span Distribution Factors: DFMFmax 0.391ï½ (Distribution Factor for Moment) DFSFmax 0.558ï½ (Distribution Factor for Shear) Backward Span Distribution Factors: DFMBmax 0.391ï½ (Distribution Factor for Moment) DFSBmax 0.558ï½ (Distribution Factor for Shear)
212 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT LIVE LOAD FOR SIMPLY SUPPORTED BRIDGE: HL-93 Loading: According to AASHTO LRFD 3.6.1.2.1, HL-93 consists of Design Truck + Design Lane Load or Design Tandem + Design Lane Load. Design Truck rather than Design Tandem + Design Lane Load controls the maximum Live Load Reactions at an interior bent for a span longer than 26'. For maximum reaction, place middle axle (P2 = 32 kip) of design truck over the support at a bent between the forward and the backward span and place rear axle (P3 = 32 kip) 14' away from P2 on the longer span while placing P1 14' away from P1 on either spans yielding maximum value. P1 Front Axleï ofï Designï Truckï= P2 Middle Axleï ofï Designï Truckï= P3 Rear Axleï ofï Designï Truckï= Design Truck Axle Load: P1 8 kipïïºï½ P2 32 kipïïºï½ P3 32 kipïïºï½ AASHTO LRFDï 3.6.1.2.2ï( ) TruckT P1 P2ï« P3ï«ïºï½ Design Lane Load: wlane 0.64 klfïïºï½ AASHTO LRFDï 3.6.1.2.4ï( ) LongSpan max FSpan BSpanï¬ï ( )ïºï½ ShortSpan min FSpan BSpanï¬ï ( )ïºï½ Llong LongSpanïºï½ Lshort ShortSpanïºï½ Lane Load Reaction Lane wlane Llong Lshortï« 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Lane 44.8 kip lane ïï½ Truck Load Reaction Truck P2 P3 Llong 14ftïï¨ ï© Llong ïï« P1 max Llong 28ftïï¨ ï© Llong Lshort 14ftïï¨ ï© Lshort ï¬ï ï©ïª ï« ï¹ïº ï» ïï«ïºï½ Truck 64 kip lane ïï½ Maximum Live Load Reaction with Impact (LLRxn) over support on Bent: The Dynamic Load Allowance or Impact Factor, IM 0.33ï½ AASHTO LRFDï Tableï 3.6.2.1ï 1ï( ) LLRxn Lane Truck 1 IMï«( )ïï«ïºï½ LLRxn 129.92 kip lane ïï½ Live Load Model for Cap Loading Program: AASHTO LRFD Recommended Live Load Model For Cap Loading Program: Live Load reaction on the pier cap using distribution factors are not sufficient to design bent cap for moment and shear. Therefore, the reaction from live load is uniformly distributed to over a 10' width (which becomes W) and the reaction from the truck is applied as two concentrated loads (P and P) 6' apart. The loads act within a 12' wide traffic lane. The reaction W and the truck move across the width of the traffic lane. However, neither of the P loads can be placed closer than 2' from the edge of the traffic lane. One lane, two lanes, three lanes and so forth loaded traffic can be moved across the width of the roadway to create maximum load effects. Load on one rear wheel out of rear axle of the truck with Impact: P 0.5 P3ïï¨ ï© 1 IMï«( )ïïºï½ P 21.28 kipïï½ The Design Lane Load Width Transversely in a Lane wlaneTransW 10 ftïïºï½ AASHTO LRFD Article 3.6.1.2.1 The uniform load portion of the Live Load, kip/station for Cap Loading Program: W LLRxn 2 Pïï( ) Staï wlaneTransW ïºï½ W 2.184 kip incr ïï½
213 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT LOADS generated above will be placed into a CAP LOADING PROGRAM to obtain moment and shear values for Bent Cap. Torsion on Bent Cap per Beam and per Drilled Shaft: Torsional load about center line of bent cap occurs due to horizontal loads acting on the superstructure perpendicular to the bent length or along the bridge length. Braking force, Centrifugal force, WS on superstructure, and WL cause torsion on bent. In addition, torque about center line of bent cap for the dead load reaction on beam brg location occurs due to differences in forward and backward span length and eccentricity between center line of bent cap and brg location. Torsion can be neglected if Tu<0.25ï¦Tcr (AASHTO LRFD 5.8.2.1) The maximum torsional effects on the pier cap will be obtained from RISA frame analysis under loading as stated in AASHTO LRFD SECTION 3 for different load combinations using AASHTO LRFD Table 3.4.1-1
214 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 2. BENT CAP FLEXURAL DESIGN FLEXURAL DESIGN OF BENT CAP: h( ) b( ) f'c 5.0 ksiïïºï½ fy 60 ksiïïºï½ Es 29000 ksiïïºï½ Ïm 0.9ïºï½ Ïv 0.9ïºï½ Ïn 1ïºï½ γc 0.150 kcfïïºï½ bcover 2 inïïºï½ tcover 2 inïïºï½ h 5 ftïïºï½ b 4.5 ftïïºï½ Ec Ecapïºï½ n round Es Ec 0ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ (AASHTO LRFD 5.7.1) n 7ï½ EIcap1 Ec b h3ïï¨ ï© 12 ïïºï½ Applicable forï 0ï CapLï£ 6ï£ 41 CapLï£ 47ï£ï¬ï EIcap1 2.894 10 7ï´ kip ft2ïïï½ ycg2 wCap hCapï hCap 2 ï 2 wFoam hFoamï( )ï hFoam 2 hbSï«ï¦ï§ï¨ ï¶ï·ï¸ïï wCap hCapï 2 wFoam hFoamï( )ïïïºï½ (ycg of from Bottom of Cap Section) ycg2 29.817 inïï½ Icap2 wCap hCap3ï 12 wCap hCapï hCap 2 ycg2ïï¦ï§ï¨ ï¶ï·ï¸ 2 ïï« 2ï wFoam hFoam 3ï 12 wFoam hFoamï hFoam 2 hbSï« ycg2ïï¦ï§ï¨ ï¶ï·ï¸ 2 ïï« ï©ïªï« ï¹ïºï»ïï« ï®ï®ï®ïºï½ Icap2 902191.259 in 4ïï½ EIcap2 Ec Icap2ïïºï½ Applicable forï 6ï CapLï£ 41ï£ EIcap2 2.686 10 7ï´ kip ft2ïïï½ OUTPUT of BENT CAP LOADING PROGRAM: The maximum load effects from different applicable limit states: DEAD LOAD MdlPos 3309.6 kftïïºï½ MdlNeg 30.1 kftïïºï½ SERVICE I MsPos 5377.1 kftïïºï½ MsNeg 45.1 kftïïºï½
215 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT STRENGTH I MuPos 7830.6 kftïïºï½ MuNeg 64.6 kftïïºï½ FLEXURE DESIGN: AASHTO LRFD 5.7.3.3.2 MINIMUM FLEXURAL REINFORCEMENT Factored Flexural Resistance, Mr, must be greater than or equal to the lesser of 1.2Mcr or 1.33 Mu. Applicable to both positive and negative moment. Modulus of rupture fr 0.37 f'c ksiïïºï½ (AASHTO LRFD EQ 5.4.2.6) fr 0.827 ksiïï½ S Icap2 ycg2 ïºï½ (Bottom Section Modulus for Positive Moment) S 30257.581 in3ïï½ Cracking moment Mcr S frïïºï½ (AASHTO LRFD EQ 5.7.3.3.2-1) Mcr 2086.122 kip ftïïï½ Mcr1 1.2 Mcrïïºï½ Mcr1 2503.346 kip ftïïï½ Mcr2 1.33 max MuPos MuNegï¬ï ï¨ ï©ïïºï½ Mcr2 10414.698 kip ftïïï½ Mcr_min min Mcr1 Mcr2ï¬ï ï¨ ï©ïºï½ Therefore Mr must be greater than Mcr_min 2503.346 kip ftïïï½ Moment Capacity Design (Positive Moment, Bottom Bars B) AASHTO LRFD 5.7.3.2 Bottom Steel arrangement for the Cap: Input no. of total rebar in a row from bottom of cap up to 12 rows (in unnecessary rows input zero) Np 9 9 9 0 0 0 0 0 0 0 0 0( )ïºï½ Input area of rebar corresponding to above rows from bottom of cap, not applicable for mixed rebar in a single row Abp 1.56 1.56 1.56 0 0 0 0 0 0 0 0 0( ) in 2ïïºï½ Input center to center vertical distance between each rebar row starting from bottom of cap clp 3.5 4 4 0 0 0 0 0 0 0 0 0( ) inïïºï½ dc Calc for Pos Moment nsPos 3ï½ (No. of Bottom or Positive Steel Layers) Distance from centroid of positive rebar to extreme bottom tension fiber (dcPos): dcPos Ayp0 0ï¬ï ï¨ ï© inïïºï½ dcPos 7.5 inïï½ Effective depth from centroid of bottom rebar to extreme compression fiber (dPos): dPos h dcPosïïºï½ dPos 52.5 inïï½
216 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Compression Block depth under ultimate load AASHTO LRFD 5.7.2.2 β1 min 0.85 max 0.65 0.85 0.05ksi f'c 4 ksiïïï¨ ï©ïï¬ï ï©ïªï« ï¹ïºï»ï¬ï ï©ïªï« ï¹ïºï»ïºï½ β1 0.8ï½ The Amount of Bottom or Positive Steel As Required, AsReq 0.85 f'cï bï dPosï fy ï¦ï§ ï¨ ï¶ï· ï¸ 1 1 2 MuPosï 0.85 Ïmï f'cï bï dPos2ï ïï ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ïïºï½ AsReq 36.454 in 2ïï½ The Amount of Positive As Provided, NofBarsPos Npï¥ïºï½ NofBarsPos 27ï½ AsPos Ayp0 1ï¬ï ï¨ ï© in2ïïºï½ AsPos 42.12 in2ïï½ htS h hFoamï hbSïïºï½ (Top solid depth) htS 14 inïï½ Compression depth under ultimate load cPos AsPos fyï 0.85 f'cï β1ï bï ïºï½ (AASHTO LRFD EQ 5.7.3.1.1-4) cPos 13.765 inïï½ aPos β1 cPosïïºï½ aPos htSï¼ OKï¬ï ï¨ ï© (AASHTO LRFD 5.7.3.2.2) aPos 11.012 inïï½ Nominal flexural resistance: MnPos AsPos fyï dPos aPos 2 ïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ (AASHTO LRFD EQ 5.7.3.2.2-1) MnPos 9896.961 kip ftïïï½ Tension controlled resistance factor for flexure ÏmPos min 0.65 0.15 dPos cPos 1ïï¦ï§ ï¨ ï¶ï· ï¸ ïï« 0.9ï¬ï ï©ïª ï« ï¹ïº ï» ïºï½ (AASHTO LRFD EQ 5.5.4.2.1-2) ÏmPos 0.9ï½ or simply use, Ïm 0.9ï½ (AASHTO LRFD 5.5.4.2) MrPos ÏmPos MnPosïïºï½ (AASHTO LRFD EQ 5.7.3.2.1-1) MrPos 8907.265 kip ftïïï½ MuPos 7830.6 kip ftïïï½ MinReinChkPos if MrPos Mcr_minï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ MinReinChkPos "OK"ï½
217 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT UltimateMomChkPos if MrPos MuPosï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ UltimateMomChkPos "OK"ï½ Moment Capacity Design (Negative Moment, Top Bars A) AASHTO LRFD 5.7.3.2 Top Steel arrangement for the Cap: Input no. of total rebar in a row from top of cap up to 12 rows (in unnecessary rows input zero) Nn 6 6 0 0 0 0 0 0 0 0 0 0( )ïºï½ Input area of rebar corresponding to above rows from top of cap, not applicable for mixed rebar in a single row Abn 0.6 1.27 0 0 0 0 0 0 0 0 0 0( ) in 2ïïºï½ Input center to center vertical distance between each rebar row starting from top of cap cln 3.5 4 0 0 0 0 0 0 0 0 0 0( ) inïïºï½ dc Calc for Neg. Moment nsNeg 2ï½ (No. of Negative or Top Steel Layers) Distance from centroid of negative rebar to top extreme tension fiber (dcNeg): dcNeg Ayn0 0ï¬ï ï¨ ï© inïïºï½ dcNeg 6.217 inïï½ Effective depth from centroid of top rebar to extreme compression fiber (dNeg): dNeg h dcNegïïºï½ dNeg 53.783 inïï½ The Amount of Negative As Required, AsReq 0.85 f'cï bï dNegï fy ï¦ï§ ï¨ ï¶ï· ï¸ 1 1 2 MuNegï 0.85 Ïmï f'cï bï dNeg2ï ïï ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ïïºï½ AsReq 0.267 in 2ïï½ The Amount of Negative As Provided, NofBarsNeg Nnï¥ïºï½ NofBarsNeg 12ï½ AsNeg Ayn0 1ï¬ï ï¨ ï© in2ïïºï½ AsNeg 11.22 in2ïï½ Compression depth under ultimate load cNeg AsNeg fyï 0.85 f'cï β1ï bï ïºï½ cNeg 3.667 inïï½ aNeg β1 cNegïïºï½ aNeg 2.933 inïï½ Thus, nominal flexural resistance:
218 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT MnNeg AsNeg fyï dNeg aNeg 2 ïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MnNeg 2934.97 kip ftïïï½ Factored flexural resistance MrNeg Ïm MnNegïïºï½ MrNeg 2641.473 kip ftïïï½ MuNeg 64.6 kip ftïïï½ MinReinChkNeg if MrNeg Mcr_minï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ MinReinChkNeg "OK"ï½ UltimateMomChkNeg if MrNeg MuNegï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ UltimateMomChkNeg "OK"ï½ Control of Cracking at Service Limit State AASHTO LRFD 5.7.3.4 exposure_cond 1ïºï½ (for exposure condition, input Class 1 = 1 and Class 2 = 2) γe if exposure_cond 1= 1ï¬ï 0.75ï¬ï ( )ïºï½ (Exposure condition factor) γe 1ï½ sidecTop sidecBotï¨ ï© 5.625 4.75( ) inïïºï½ (Input side cover for Top and Bottom Rebars) Positive Moment (Bottom Bars B) To find Smax: S is spacing of first layer of rebar closest to tension face n round Es Ec 0ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ (modular ratio) n 7ï½ ÏPos AsPos b dPosï ïºï½ ÏPos 0.0149ï½ kPos ÏPos nï 1ï«ï¨ ï©2 1ï ÏPos nïïïºï½ kPos 0.364ï½(Applicable for Solid Rectangular Section) kdP kPos dPosïïºï½ Location of NA from Top of Cap for Pos Moment kdP 19.098 inïï½ StressBlockPos if kdP htSï³ "T-Section"ï¬ï "Rec-Section"ï¬ï ï¨ ï©ïºï½ StressBlockPos "T-Section"ï½ Comression Forceï Tension Forceï= OR Moment ofï Comressionï Areaï Moment ofï Tensionï Areaï aboutï NAï= b kdPosï¨ ï©2ï 2 wFoamï kdPos hStopïï¨ ï©2ïï 2 nï AsPosï dPos kdPosïï¨ ï©ï= b 2 wFoamïï( ) kdPosï¨ ï©2ï 2 nï AsPosï 4 wFoamï hStopïï«ï¨ ï© kdPosï¨ ï©ïï« 2 wFoam hStop2ï n AsPosï dPosïï«ï¦ï¨ ï¶ï¸ïï 0=
219 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT kdPos 2 nï AsPosï 4 wFoamï htSïï«ï¨ ï©ï 2 nï AsPosï 4 wFoamï htSïï«ï¨ ï©2 4 b 2 wFoamïï( )ï 2ï wFoam htS 2ï n AsPosï dPosïï«ï¦ï¨ ï¶ï¸ïï« ï®ï®ï®ï« 2 b 2 wFoamïï( )ïïºï½ kdPos 19.405 inïï½ Location of NA from Top of Cap Location of Resultant Compression force from NA for Positive Moment: xPos b kdPosï¨ ï©2 3 ï 2 3 wFoamï kdPos htSïï¨ ï©2ï 1 htSkdPosï ï¦ï§ ï¨ ï¶ï· ï¸ ïï 1 2 bï kdPosï wFoam kdPos htSïï¨ ï©ï 1 htSkdPosï ï¦ï§ ï¨ ï¶ï· ï¸ ïï ïºï½ xPos 13.328 inïï½ jdPos dPos kdPosï xPosï«ïºï½ jdPos 46.423 inïï½ Tensile Stress at Service Limit State fssPos MsPos AsPos jdPosï ïºï½ fssPos 33 ksiïï½ dc1Pos clp0 0ï¬ï ïºï½ (Distance of bottom first row rebar closest to tension face) dc1Pos 3.5 inïï½ Î²sPos 1 dc1Pos 0.7 h dc1Posïï¨ ï©ïï«ïºï½ βsPos 1.088ï½ smaxPos 700 kip in γeï βsPos fssPosï 2 dc1Posïïïºï½ AASHTO LRFD EQ (5.7.3.4-1) smaxPos 12.488 inïï½ sActualPos b 2 sidecBotïï Np0 0ï¬ï 1ïïºï½ (Equal horizontal spacing of bottom first rebar row closest to tension face) sActualPos 5.563 inïï½ Actual Max Spacing Provided in Bottom first row closest to Tension Face, saPosProvided 7 inïïºï½ sActualPos max saPosProvided sActualPosï¬ï ï¨ ï©ïºï½ sActualPos 7 inïï½ SpacingCheckPos if smaxPos sActualPosï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ SpacingCheckPos "OK"ï½
220 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Negative Moment (Top Bars A) ÏNeg AsNeg b dNegï ïºï½ ÏNeg 3.863 10 3ïï´ï½ kNeg ÏNeg nï 1ï«ï¨ ï©2 1ï ÏNeg nïïïºï½ (Applicable for Solid Rectangular Section) kNeg 0.207ï½ kdN kNeg dNegïïºï½ Location of NA from Bottom of Cap for Neg Moment kdN 11.138 inïï½ StressBlockNeg if kdN hbSï³ "T-Section"ï¬ï "Rec-Section"ï¬ï ï¨ ï©ïºï½ StressBlockNeg "Rec-Section"ï½ jNeg 1 kNeg 3 ïïºï½ jNeg 0.931ï½ fssNeg MsNeg AsNeg jNegï dNegï ïºï½ fssNeg 0.963 ksiïï½ dc1Neg cln0 0ï¬ï ïºï½ (Distance of top first row rebar closest to tension face) dc1Neg 3.5 inïï½ Î²sNeg 1 dc1Neg 0.7 h dc1Negïï¨ ï©ïï«ïºï½ βsNeg 1.088ï½ smaxNeg 700 kip in γeï βsNeg fssNegï 2 dc1Negïïïºï½ smaxNeg 660.561 inïï½ sActualNeg b 2 sidecTopïï Nn0 0ï¬ï 1ïïºï½ (Equal horizontal spacing of top first rebar row closest to tension face) sActualNeg 8.55 inïï½ Actual Max Spacing Provided in Top first row closest to Tension Face, saNegProvided 11.125 inïïºï½ sActualNeg max saNegProvided sActualNegï¬ï ï¨ ï©ïºï½ sActualNeg 11.125 inïï½ SpacingCheckNeg if smaxNeg sActualNegï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ SpacingCheckNeg "OK"ï½ SUMMARY OF FLEXURE DESIGN:
221 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Bottom Rebar or B Bars: use 27~#11 bars @ 9 bars in each row of 3 rows Top Rebar or A Bars: use 6~#7 bars and 6~#10 bars in first and 2nd row from top SKIN REINFORCEMENT (BARS T) AASHTO LRFD 5.7.3.4 SkBarNo 8ïºï½ (Size of a skin bar) Area of a skin bar, AskBar 0.79 in 2ïïºï½ dcTop clnï¥ïºï½ dcTop 7.5 inïï½ dcBot clpï¥ïºï½ dcBot 11.5 inïï½ Effective Depth from centroid of ExtremeTension Steel to Extreme compression Fiber (dl): dl max h clp0 0ï¬ï ï h cln0 0ï¬ï ïï¬ï ï¨ ï©ïºï½ dl 56.5 inïï½ Effective Depth from centroid of Tension Steel to Extreme compression Fiber (de): de max dPos dNegï¬ï ï¨ ï©ïºï½ de 53.783 inïï½ As min AsNeg AsPosï¬ï ï¨ ï©ïºï½ min. of negative and positive reinforcement As 11.22 in2ïï½ dskin h dcTop dcBotï«ï¨ ï©ïïºï½ dskin 41 inïï½ Skin Reinforcement Requirement: AASHTO LRFD EQ 5.7.3.4-2 AskReq if dl 3ftï¾ min 0.012 in ft ï dl 30 inïïï¨ ï©ï dskinï As Apsï«4ï¬ï ï©ïªï« ï¹ïºï»ï¬ï 0in 2ï¬ï ï©ïªï« ï¹ïºï»ïºï½ AskReq 1.087 in 2ïï½ NoAskbar1 R AskReq AskBar ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ NoAskbar1 2ï½ per Side Maximum Spacing of Skin Reinforcement: SskMax min de 6 12 inïï¬ï ï¦ï§ï¨ ï¶ï·ï¸ïºï½ AASHTO LRFD 5.7.3.4 SskMax 8.964 inïï½ NoAskbar2 if dl 3ftï¾ R dskin SskMax 1ïï¦ï§ ï¨ ï¶ï· ï¸ ï¬ï 1ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ NoAskbar2 4ï½ per Side NofSideBarsreq max NoAskbar1 NoAskbar2ï¬ï ï¨ ï©ïºï½ NofSideBarsreq 4ï½ SskRequired dskin 1 NofSideBarsreqï« ïºï½ SskRequired 8.2 inïï½
222 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT NofSideBars 5ïºï½ (No. of Side Bars Provided) SskProvided dskin 1 NofSideBarsï«ïºï½ SskProvided 6.833 inïï½ SskChk if SskProvided SskMaxï¼ "OK"ï¬ï "N.G."ï¬ï ï¨ ï©ïºï½ SskChk "OK"ï½ Therefore Use: NofSideBars 5ï½ and Size SkBarNo 8ï½ 3. BENT CAP SHEAR AND TORSION DESIGN SHEAR DESIGN OF CAP: Effective Shear Depth, dv max de a 2 ï 0.9 deï 0.72 hï ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ = (AASHTO LRFD 5.8.2.9) dv Distance betweenï theï resultantsï ofï tensileï andï compressiveï Forceï= ds Effective depthï fromï cgï ofï theï nonprestressedï tensileï steelï toï extremeï compressionï fiberï= dp Effective depthï fromï cgï ofï theï prestressedï tendonï toï extremeï compressionï fiberï= de Effective depthï fromï centroidï ofï theï tensileï forceï toï extremeï compressionï fiberï atï criticalï shearï Locationï= θ Angle ofï inclinationï diagonalï compressiveï stressï= Ao Area enclosedï byï shearï flowï pathï includingï areaï ofï holesï thereinï= Ac Area ofï concreteï onï flexuralï tensionï sideï ofï memberï shownï inï AASHTOï LRFDï Figureï 5.8.3.4.2ï 1ï= Aoh Area enclosedï byï centerlineï ofï exteriorï closedï transverseï torsionï reinforcementï includingï areaï ofï holesï thereinï= Total Pos Flexural Steel Area, As AsPosïºï½ As 42.12 in 2ïï½ Nominal Flexure, Mn MnPosïºï½ Mn 9896.961 kftïï½ Stress block Depth, a aPosïºï½ a 11.012 inïï½ Effective Depth, de dPosïºï½ de 52.5 inïï½ Effective web Width at critical Location, bv bïºï½ bv 4.5 ftïï½ Input initial ï±ï¬ θ 35 degïïºï½ cotθ cot θ( )ïºï½ Shear Resistance Factor, Ïv 0.9ïºï½ Cap Depth & Width, h 60 inïï½ b 54 inïï½
223 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Moment Arm, de a 2 ïï¦ï§ï¨ ï¶ï·ï¸ 46.994 inïï½ 0.9 deï 47.25 inïï½ 0.72 hï 43.2 inïï½ Effective Shear Depth at Critical Location, dv max de a 2 ï 0.9 deï 0.72 hï ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ ïºï½ (AASHTO LRFD 5.8.2.9) dv 47.25 inïï½ hh h tcoverï bcoverïïºï½ (Height of shear reinforcement) hh 56 inïï½ bh b 2 bcoverïïïºï½ (Width of shear reinforcement) bh 50 inïï½ ph 2 hh bhï«ï¨ ï©ïºï½ (Perimeter of shear reinforcement) ph 212 inïï½ Aoh hhï¨ ï© bhï¨ ï©ïïºï½ (Area enclosed by the shear reinforcement) Aoh 2800 in2ïï½ Ao 0.85 Aohïïºï½ (AASHTO LRFD C5.8.2.1) Ao 2380 in 2ïï½ Ac 0.5 bï hïïºï½ AASHTO LRFDï FIGUREï 5.8.3.4.2ï 1ï( ) Ac 1620 in 2ïï½ Yield strength & Modulus of Elasticity of Steel Reinforcement: fy Esï¨ ï© 60 29000( ) ksiïïºï½ AASHTO LRFDï 5.4.3.1ï 5.4.3.2ï¬ï ( ) Input Mu, Tu, Vu, Nu for the critical section to be investigated: (Loads from Bent Cap & RISA Analysis) Mu Tuï¨ ï© 1314.8 964.6( ) kftïïºï½ Vu Nuï¨ ï© 665.4 0( ) kipïïºï½ M'u max Mu Vu Vpï dvïï¬ï ï¨ ï©ïºï½ AASHTO LRFD B5.2 M'u 2620.013 kip ftïïï½ V'u Vu 2 0.9 phï Tuï 2 Aoï ï¦ï§ ï¨ ï¶ï· ï¸ 2 ï«ïºï½ (Equivalent shear) AASHTO LRFD EQ (5.8.2.1-6) for solid section V'u 811.194 kipïï½ Assuming atleastï minimumï transverseï reinforcementï isï providedï (Always provide min. transverse reinf.) εx M'u dv ï¦ï§ ï¨ ï¶ï· ï¸ 0.5 Nuïï« 0.5 V'u Vpïï¨ ï©ï cotθïï« Aps fpoïï 2 Es Asï Ep Apsïï«ï¨ ï©ï= (Strain from Appendix B5) AASHTO LRFD EQ (B5.2-1)
224 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT vu Vu Ïv Vpïïï¨ ï© Ïv bvï dvï ïºï½ (Shear Stress) AASHTO LRFD EQ (5.8.2.9-1) vu 0.29 ksiïï½ r max 0.075 vu f'c ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ (Shear stress ratio) r 0.075ï½ Determining Beta & Theta After Interpolating the value of Î Î( ) Î 30.773 degïï½ Î 2.572ï½ Nominal Shear Resistance by Concrete, Vc 0.0316 Îï f'c ksiïï bvï dvïïºï½ AASHTO LRFD EQ (5.8.3.3-3) Vc 463.7 kipïï½ Vu 665.4 kipïï½ 0.5 Ïvï Vc Vpï«ï¨ ï©ï 208.673 kipïï½ REGION REQUIRING TRANSVERSE REINFORCEMENT: AASHTO LRFD 5.8.2.4 Vu 0.5 Ïvï Vc Vpï«ï¨ ï©ïï¾ AASHTO LRFD EQ (5.8.2.4-1) check if Vu 0.5 Ïvï Vc Vpï«ï¨ ï©ïï¾ "Provide Shear Reinf"ï¬ï "No reinf."ï¬ï ï©ï« ï¹ï»ïºï½ check "Provide Shear Reinf"ï½ Vn min Vc Vsï« Vpï« 0.25 f'cï bvï dvï Vpï« ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ = (Nominal Shear Resistance) AASHTO LRFDï EQï 5.8.3.3 1ï 2ï¬ï ( )ï Vs Av fyï dvï cotθ cotαï«( )ï sinαï S = (Shear Resistance of Steel) AASHTO LRFDï EQï 5.8.3.3 4ï( )ï Vs Av fyï dvï cotθï S = Shear Resistanceï ofï Steelï whenï α 90 degï=ï¬ï ( ) AASHTO LRFD EQ (C5.8.3.3-1) Sv 6 inïïºï½ (Input Stirrup Spacing) Vp 0 kipïï½ Vu Vcï¨ ï© 665.4 463.718( ) kipïï½ fy 60 ksiïï½ dv 47.25 inïï½ Î 30.773 degïï½ (Derive from AASHTO LRFD EQ 5.8.3.3-1, C5.8.3.3-1 and ï¦Vn >= Vu)Av_req Vu Ïv Vcï Vpï ï¦ï§ ï¨ ï¶ï· ï¸ Sv fy dvï cotÎï ï¦ï§ ï¨ ï¶ï· ï¸ ïïºï½ Av_req 0.3474 in 2ïï½ Torsional Steel:
225 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT At Tu 2 Ïvï Aoï fyï cotÎï Svïïºï½ (Derive from AASHTO LRFD EQ 5.8.3.6.2-1 and ï¦Tn >= Tu) At 0.161 in 2ïï½ Avt_req Av_req 2 Atïï«ïºï½ Shear Torsionï«( ) Avt_req 0.669 in 2ïï½ Avt 4 0.44 in 2ïï¨ ï©ïïºï½ (Use 2 #6 double leg Stirrup at Sv c/c,) Provided, Avt 1.76 in2ïï½ Avt_check if Avt Avt_reqï¾ "OK"ï¬ï "NG"ï¬ï ï¨ ï©ïºï½ Avt_check "OK"ï½ AASHTO LRFDï Articleï 5.8.2.7ïMaximum Spacing Check: Vu 665.4 kipïï½ 0.125 f'cï bvï dvï 1594.69 kipïï½ Svmax if Vu 0.125 f'cï bvï dvïï¼ min 0.8 dvï 24 inïï¬ï ï¨ ï©ï¬ï min 0.4 dvï 12 inïï¬ï ï¨ ï©ï¬ï ï¨ ï©ïºï½ Svmax 24 inïï½ Svmax_check if Sv Svmaxï¼ "OK"ï¬ï "use lower spacing"ï¬ï ï¨ ï©ïºï½ Svmax_check "OK"ï½ Av Avt Atïïºï½ (Shear Reinf. without Torsion Reinf.) Av 1.599 in 2ïï½ Vs Av fyï dvï cotÎï Sv ïºï½ Vs 1268.855 kipïï½ AASHTO LRFDï Articleï 5.8.2.5ïMinimum Transverse Reinforcement Check: bv 54 inïï½ Avmin 0.0316 f'c ksiïï bv Svï fy ïïºï½ AASHTO LRFDï EQï 5.8.2.5 1ï( )ï Avmin 0.382 in 2ïï½ Avmin_check if Avt Avminï¾ "OK"ï¬ï "NG"ï¬ï ï¨ ï©ïºï½ Avmin_check "OK"ï½ Maximum Nominal Shear: To ensure that the concrete in the web of beam will not crush prior to yield of shear reinforcement, LRFD Specification has given an upper limit of 0.25 f'cï bvï dvï Vpï« 3189.375 kipïï½ Vc Vsï« Vpï« 1732.573 kipïï½ Vn min Vc Vsï« Vpï« 0.25 f'cï bvï dvï Vpï« ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ïºï½ AASHTO LRFDï EQï 5.8.3.3 1ï 2ï¬ï ( )ï Vn 1732.573 kipïï½ Ïv Vnï 1559.316 kipïï½ Vu 665.4 kipïï½ ÏVn_check if Ïv Vnï Vuï¾ "OK"ï¬ï "NG"ï¬ï ï¨ ï©ïºï½ ÏVn_check "OK"ï½ Torsional Resistance,
226 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Tn 2 Aoï 0.5 Avtïï¨ ï©ï fyï cotÎï Sv ïºï½ AASHTO LRFDï EQï 5.8.3.6.2 1ï( )ï Ïv Tnï 5275.8 kip ftïïï½ Longitudinal Reinforcement Requirements including Torsion: AASHTO LRFDï 5.8.3.6.3ï AASHTO LRFDï EQ 5.8.3.6.3 1ï( )ï Applicable for solid section with Torsion Aps fpsï As fyïï« M'u Ïm dvï ï¦ï§ ï¨ ï¶ï· ï¸ 0.5 Nuï Ïn ï« cotÎ VuÏv Vpï 0.5 V'sïï ï¦ï§ ï¨ ï¶ï· ï¸ 2 0.45 phï Tuï 2 Ïvï Aoï ï¦ï§ ï¨ ï¶ï· ï¸ 2 ï«ïï«ï³ Ïm Ïv Ïnï¨ ï© 0.9 0.9 1( )ïºï½ As fyï Aps fpsïï« 2527.2 kipïï½ M'u 2620.013 kip ftïïï½ Vu 665.4 kipïï½ Nu 0 kipïï½ Vs 1268.855 kipïï½ Tu 964.6 kip ftïïï½ ph 212 inïï½ Vp 0 kipïï½ As 42.12 in 2ïï½ V's min Vu Ïv Vsï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ AASHTO LRFDï 5.8.3.5ï V's 739.333 kipïï½ F M'u Ïm dvï ï¦ï§ ï¨ ï¶ï· ï¸ 0.5 Nuï Ïn ï« cotÎ VuÏv Vpï 0.5 V'sïï ï¦ï§ ï¨ ï¶ï· ï¸ 2 0.45 Tuï phï 2 Ïvï Aoï ï¦ï§ ï¨ ï¶ï· ï¸ 2 ï«ïï«ïºï½ F 1496.141 kipïï½ Fcheck if Aps fpsï As fyïï« Fï³ "OK"ï¬ï "NG"ï¬ï ï¨ ï©ïºï½ AASHTO LRFDï EQ 5.8.3.6.3 1ï( )ï Fcheck "OK"ï½
227 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 4. COLUMN/DRILLED SHAFT LOADING AND DESIGN Superstructure to substructure force: AASHTO LRFDï SECTIONï 3ï LOADSï andï LOADï COMBINATIONSï Subscript: X = Parallel to the Bent cap Length and Z = Perpendicular to the bent Cap Length th 2 inïïºï½ (Haunch Thickness) Beam Depth, BmH FBmDïºï½ ColH HCol 0 ftïï«ïºï½ (Column height + 0 ft Column Capital) TribuLength FSpan BSpanï« 2 ïºï½ Scour Depth: hscour 0 ftïïºï½ Scour to Fixity Depth: hscf min 3 DsDiaï 10 ftïï¬ï ( )ïºï½ Total Drilled Shaft height: DsH hscour hscfï«ïºï½ DsH 10 ftïï½ ho BrgTh BmHï« thï« SlabThï«ïºï½ (Top of cap to top of slab height) ho 3.683 ftïï½ h6 ho 6ftï«ïºï½ (Top of cap to top of slab height + 6 ft) h6 9.683 ftïï½ hsup BmH thï« SlabThï« RailHï«ïºï½ (Height of Superstructure) hsup 6.225 ftïï½ h1 DsH ColHï« hCap 2 ï«ïºï½ (Height of Cap cg from Fixity of Dshaft) h1 34.5 ftïï½ h2 DsH ColHï« hCapï« h6ï«ïºï½ h2 46.683 ftïï½ h3 DsH ColHï« hCapï« BrgThï« hsup 2 ï«ïºï½ h3 40.404 ftïï½ Tributary area for Superstructure, Asuper hsup( ) TribuLength( )ïïºï½ Asuper 435.75 ft 2ïï½
228 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT LIVE LOAD REACTIONS: LL Live load Reaction LL on cap can be taken only the vertical Rxn occurs when HL93 is on both the forward and backward span or when HL93 Loading is on one span only which causes torsion too. To maximize the torsion, LL only acts on the longer span between forward and backward span. For maximum reaction, place rear axle (P3 = 32 kip) over the support at bent while the design truck traveling along the span. Maximum Forward Span Design Truck (FTruck) & Lane Load Reaction (FLane): FTruck P3 P2 FSpan 14 ftïï( ) FSpan ï©ïªï« ï¹ïºï»ïï« P1 FSpan 28ftï( ) FSpan ïï«ïºï½ FTruck 62.4 kipïï½ FLane wlane FSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ FLane 22.4 kip lane ïï½ Forward Span Live Load Reactions with Impact (FLLRxn): FLLRxn FLane FTruck 1 IMï«( )ïï«ïºï½ FLLRxn 105.392 kip lane ïï½ Maximum Backward Span Design Truck (BTruck) & Lane Load Reaction (BLane): BTruck P3 P2 BSpan 14 ftïï( ) BSpan ï©ïªï« ï¹ïºï»ïï« P1 BSpan 28ftï( ) BSpan ïï«ïºï½ BTruck 62.4 kipïï½ BLane wlane BSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ BLane 22.4 kip lane ïï½ Backward Span Live Load Reactions with Impact (BLLRxn): BLLRxn BLane BTruck 1 IMï«( )ïï«ïºï½ BLLRxn 105.392 kip lane ïï½ Live Load Reactions per Beam with Impact (BmLLRxn) using Distribution Factors: BmLLRxn LLRxn( ) max DFSFmax DFSBmaxï¬ï ï¨ ï©ïïºï½ Max reactionï whenï midï axleï onï supportï( ) BmLLRxn 72.556 kipbeamïï½ FBmLLRxn FLLRxn( ) DFSFmaxïïºï½ Only Forwardï Spanï isï Loadedï( ) FBmLLRxn 58.858 kip beam ïï½ BBmLLRxn BLLRxn( ) DFSBmaxïïºï½ Only Backwardï Spanï isï Loadedï( ) BBmLLRxn 58.858 kip beam ïï½ Torsion due to the eccentricity from CL of Bearing to CL of Bent when only Longer Span is loaded with HL-93 Loading TorsionLL max FBmLLRxn BBmLLRxnï¬ï ( ) ebrgïïºï½ TorsionLL 63.763 kip ftï beam ïï½ Live Load Reactions per Beam without Impact (BmLLRxnn) using Distribution Factors: BmLLRxnn Lane Truckï«( ) max DFSFmax DFSBmaxï¬ï ï¨ ï©ïïºï½ BmLLRxnn 60.761 kipbeamïï½ FBmLLRxnn FLane FTruckï«( ) DFSFmaxï¨ ï©ïïºï½ FBmLLRxnn 47.358 kipbeamïï½ BBmLLRxnn BLane BTruckï«( ) DFSBmaxï¨ ï©ïïºï½ BBmLLRxnn 47.358 kipbeamïï½ Torsion due to the eccentricity of CL of Bearing and CL of Bent without Impact
229 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT TorsionLLn max FBmLLRxnn BBmLLRxnnï¬ï ï¨ ï© ebrgïïºï½ TorsionLLn 51.305 kftbeamïï½ CENTRIFUGAL FORCE: CF (AASHTO LRFD 3.6.3) Skew Angle of Bridge, θ 0 degïïºï½ Design Speed v 45 mphïïºï½ f g( ) 4 3 32.2 ft sec2 ïï¦ï§ï¨ ï¶ï·ï¸ ïºï½Degree of Curve, Ïc 0.00001 degïïºï½ (Input 4o curve or 0.00001o for 0o curve) Radius of Curvature, Rc 360 degï( ) 100ï ftï 2 Ïï Ïcï ïºï½ Rc 572957795.131 ftïï½ Rc â ftï=ï¨ ï© Centri. Force Factor, C f v2 Rc gï ïïºï½ AASHTO LRFDï EQï 3.6.3ï 1ï( ) C 0ï½ Pcf C TruckTï NofLane( )ï m( )ïïºï½ Pcf 0 kipïï½ Centrifugal force parallel to bent (X-direction) CFX Pcf cos θ( )ï NofBm ï¦ï§ï¨ ï¶ï·ï¸ïºï½ CFX 0 kip beam ïï½ Centrifugal force normal to bent (Z-direction) CFZ Pcf sin θ( )ï NofBm ï¦ï§ï¨ ï¶ï·ï¸ïºï½ CFZ 0 kip beam ïï½ Moments at cg of the Bent Cap due to Centrifugal Force MCF_X CFZ h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MCF_X 0 kft beam ïï½ MCF_Z CFX h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MCF_Z 0 kft beam ïï½ BRAKING FORCE: BR (AASHTO LRFD 3.6.4) The braking force shall be taken as maximum of 5% of the Resultant Truck plus lane load OR 5% of the Design Tandem plus Lane Load or 25% of the design truck. Pbr1 5% Lane TruckTï«( )ï NofLane( )ï m( )ïïºï½ Truck Laneï«( ) Pbr1 14.892 kipïï½ Pbr2 5% Lane 50 kipïï«( )ï NofLane( )ï m( )ïïºï½ Tandem Laneï«( ) Pbr2 12.087 kipïï½ Pbr3 25% TruckT( )ï NofLane( )ï m( )ïïºï½ DesignTruck( ) Pbr3 kipïï½ Pbr max Pbr1 Pbr2ï¬ï Pbr3ï¬ï ï¨ ï©ïºï½ Pbr 45.9 kipïï½ Braking force parallel to bent (X-direction) BRX Pbr sin θ( )ï NofBm ïºï½ BRX 0 kip beam ïï½
230 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Braking force normal to bent (Z-direction) BRZ Pbr cos θ( )ï NofBm ïºï½ BRZ 3.825 kip beam ïï½ Moments at cg of the Bent Cap due to Braking Force MBR_X BRZ h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MBR_X 46.601 kft beam ïï½ MBR_Z BRX h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MBR_Z 0 kft beam ïï½ WATER LOADS: WA (AASHTO LRFD 3.7) Note : To be applied only on bridge components below design high water surface. Substructure: V 0 ft sec ïºï½ (Design Stream Velocity) Specific Weight, γwater 62.4 pcfïïºï½ Longitudinal Stream Pressure: AASHTO LRFD 3.7.3.1 AASHTO LRFD Table 3.7.3.1-1 for Drag Coefficient, CD semicircular-nosed pier 0.7 square-ended pier 1.4 debries lodged against the pier 1.4 wedged-nosed pier with nose angle 90 deg or less 0.8 Columns and Drilled Shafts: Longitudinal Drag Force Coefficient for Column, CD_col 1.4ïºï½ Longitudinal Drag Force Coefficient for Drilled Shaft, CD_ds 0.7ïºï½ pT CD V2 2 gïï γwaterï= (Longitudinal stream pressure) AASHTO LRFD EQ (C3.7.3.1-1) pT_col CD_col V2 2 gïï γwaterïïºï½ pT_col 0 ksfïï½ pT_ds CD_ds V2 2 gïï γwaterïïºï½ pT_ds 0 ksfïï½ Lateral Stream Pressure: AASHTO LRFD 3.7.3.2
231 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT AASHTO LRFD Table 3.7.3.2-1 for Lateral Drag Coefficient, CL Angle,ï±, between direction of flowr and longitudina axis of the pie 0deg 0 5deg 0.5 10deg 0.7 20deg 0.9 >30deg 1 CL Lateral Drag Force Coefficient, CL 0.0ïºï½ Lateral stream pressure, pL CL V2 2 gïï γwaterïïºï½ pL 0 ksfïï½ Bent Cap: Longitudinal stream pressure CL 1.4ïºï½ pTcap CL V2 2 gïï γwaterïïºï½ pTcap 0 ksfïï½ WA on Columns Water force on column parallel to bent (X-direction) WAcol_X wCol pT_colïïºï½ WAcol_X 0 kip ft ïï½ If angle between direction of flow and longitudinal axis of pile = 0 then apply load at one exterior column only otherwise apply it on all columns. WA at all columns will be distributed uniformly rather than triangular distribution on Column Height. Water force on column normal to bent (Z-direction) WAcol_Z bCol pLïïºï½ WAcol_Z 0 kip ft ïï½ WA on Drilled Shafts Water force on drilled shaft parallel to bent (X-direction) WAdshaft_X DsDia pT_dsïïºï½ WAdshaft_X 0 kip ft ïï½ Water force on drilled shaft normal to bent (Z-direction) WAdshaft_Z DsDia pLïïºï½ WAdshaft_Z 0 kip ft ïï½ WA on Bent Cap (input as a punctual load) Water force on bent cap parallel to bent (X-direction) WAcap_X wCap hCapï pTcapï¨ ï©ïïºï½ (If design HW is below cap then input zero) WAcap_X 0 kipïï½ Water force on bent cap normal to bent (Z-direction) WAcap_Z hCap pLïïºï½ (If design HW is below cap then input zero) WAcap_Z 0 kip ft ïï½ WIND ON SUPERSTRUCTURE: WS (AASHTO LRFD 3.8.1.2.2) Note : Wind Loads to be applied only on bridge exposed components above water surface
232 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT AASHTO LRFD Table 3.8.1.2.2-1 specifies the wind load components for various angles of attack. In order to simplify the analysis, this calculation considers as default values those for girders which generate the maximum effect on structure. The results can be considered as conservative. For a superstructure other than a girder type and/or for a more detailed analysis, use the proper values as specified in the above mentioned table. AASHTO LRFD table 3.8.1.2.2-1 (modified) If the bridge is approximately 30â high and local wind velocities are known to be less than 100 mph, wind load for this bridge should be from AASHTO LRFD TABLE 3.8.2.2-1. Otherwise use AASHTO LRFD EQ 3.8.1.2.1-1 as mentioned above. ptsup 0.05ksfïºï½ Normal to superstructure (conservative suggested value 0.050 ksf) plsup 0.012ksfïºï½ Along Superstructure (conservative suggested value 0.019 ksf) WSchk if ptsup hsupï 0.3 klfïï³ "OK"ï¬ï "N.G."ï¬ï ï¨ ï©ïºï½ WSchk "OK"ï½ WsupLong plsup hsupï TribuLengthï NofBm ïºï½ WsupLong 0.436 kip beam ïï½ WsupTrans ptsup hsupï TribuLengthï NofBm ïºï½ WsupTrans 1.816 kip beam ïï½ Wind force on superstructure parallel to bent (X-direction) WSsuper_X WsupLong sin θ( )ï WsupTrans cos θ( )ïï«ïºï½ WSsuper_X 1.816 kipbeamïï½ Wind force on superstructure normal to bent (Z-direction) WSsuper_Z WsupLong cos θ( )ï WsupTrans sin θ( )ïï«ïºï½ WSsuper_Z 0.436 kipbeamïï½ Moments at cg of the Bent Cap due to Wind load on superstructure Msuper_X WSsuper_Z hCap 2 BrgThï« hsup 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Msuper_X 2.573 kft beam ïï½ Msuper_Z WSsuper_X hCap 2 BrgThï« hsup 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Msuper_Z 10.72 kft beam ïï½ WIND ON SUBSTRUCTURE: WS (AASHTO LRFD 3.8.1.2.3) Base Wind pressure, psub 0.04 ksfïïºï½ will be applied on exposed substructure both transverse & longitudinal direction Wind on Columns Wind force on columns parallel to bent (X-direction)
233 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT WScol_X psub bCol cos θ( )ï wCol sin θ( )ïï«( )ïï©ï« ï¹ï»ïºï½ WScol_X 0.16 kip ft ïï½ Apply WS loads at all columns even with zero degree attack angle. Wind force on columns normal to bent (Z-direction) WScol_Z psub bCol sin θ( )ï wCol cos θ( )ïï«( )ïï©ï« ï¹ï»ïºï½ WScol_Z 0.16 kip ft ïï½ Wind on Bent Cap & Ear Wall WSew_X psub hEarWallï wEarWall sin θ( )ï wCap cos θ( )ïï«( )ïïºï½ WSew_X 0 kipïï½ WSew_Z psub hEarWallï wEarWall cos θ( )ï wCap sin θ( )ïï«( )ïïºï½ WSew_Z 0 kipïï½ Wind force on bent cap parallel to bent (X-direction) WScap_X psub hCapï CapL sin θ( )ï wCap cos θ( )ïï«( )ïï©ï« ï¹ï» WSew_Xï«ïºï½ (punctual load) WScap_X 0.9 kipïï½ Wind force on bent cap normal to bent (Z-direction) WScap_Z psub hCapï CapL cos θ( )ï wCap sin θ( )ïï«( )ïï©ï« ï¹ï» WSew_Zï« CapL ïºï½ WScap_Z 0.2 kip ft ïï½ WIND ON VEHICLES: WL (AASHTO LRFD 3.8.1.3) AASHTO LRFD Table 3.8.1.3-1 specifies the wind on live load components for various angles of attack. In order to simplify the analysis, this calculation considers as default values the maximum wind components as defined in the above mentioned table. The results can be considered conservative. For a more detailed analysis, use the proper skew angle according to the table. AASHTO LRFD table 3.8.1.3-1 (suggested value 0.1 kip/ft) pWLt 0.1 kip ft ïºï½ (suggested value 0.038 kip/ft) pWLl 0.04 kip ft ïºï½ WLPar pWLl TribuLengthï NofBm ïºï½ WLPar 0.233 kip beam ïï½ WLNor pWLt TribuLengthï NofBm ïºï½ WLNor 0.583 kip beam ïï½ Wind force on live load parallel to bent (X-direction)
234 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT WLX WLNor cos θ( )ï WLPar sin θ( )ïï«ïºï½ WLX 0.583 kipbeamïï½ Wind force on live load normal to bent (Z-direction) WLZ WLNor sin θ( )ï WLPar cos θ( )ïï«ïºï½ WLZ 0.233 kipbeamïï½ Moments at cg of the Bent Cap due to Wind load on Live Load MWL_X WLZ h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MWL_X 2.843 kft beam ïï½ MWL_Z WLX h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MWL_Z 7.107 kft beam ïï½ Vertical Wind Pressure: (AASHTO LRFD 3.8.2) DeckWidth FDeckWïºï½ Bridge deck width including parapet and sidewalk Puplift 0.02ksf( )ï DeckWidthï TribuLengthïïºï½ (Acts upword Y-direction) Puplift 66.033ï kipïï½ Applied at the windward quarter-point of the deck width. Note: Applied only for Strength III and for Service IV for minimum permanent loads only. (AASHTO LRFD table 3.4,1-2, factors for permanent loads) Load Combinations: using AASHTO LRFD Table 3.4.1-1 STRENGTH_I 1.25 DCï 1.5 DWïï« 1.75 LL BRï« CFï«( )ïï« 1.0 WAïï«= STRENGTH_IA 0.9 DCï 0.65 DWïï« 1.75 LL BRï« CFï«( )ïï« 1.0 WAïï«= STRENGTH_III 1.25 DCï 1.5 DWïï« 1.4 WSïï« 1.0 WAïï« 1.4 Pupliftïï«= STRENGTH_IIIA 0.9 DCï 0.65 DWïï« 1.4 WSïï« 1.0 WAïï« 1.4 Pupliftïï«= STRENGTH_V 1.25 DCï 1.5 DWïï« 1.35 LL BRï« CFï«( )ïï« 0.4 WSïï« 1.0 WAïï« 1.0 WLïï«= STRENGTH_VA 0.9 DCï 0.65 DWïï« 1.35 LL BRï« CFï«( )ïï« 0.4 WSïï« 1.0 WAïï« 1.0 WLïï«= SERVICE_I 1.0 DCï 1.0 DWïï« 1.0 LLno_Impact BRï« CFï«ï¨ ï©ïï« 0.3 WSïï« 1.0 WAïï« 1.0 WLïï«= All these loadings as computed above such as DC, DW, LL, WL, WA, WS etc. are placed on the bent frame composed of bent cap and columns and drilled shafts. The frame is analyzed in RISA using load combinations as stated above. Output Loadings for various load combinations for column and drilled shaft are used to run PCA Column program to design the columns. It is found that 4'X4' Column with 20~#11 bars is sufficient for the loadings. Drilled shaft or other foundation shall be designed for appropriate loads. Total Vertical Foundation Load at Service I Limit State: Forward Span Superstructure DC (FFDC) & DW (FFDW):
235 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT FFDC FNofBm 2ï( ) FSuperDCIntï 2 FSuperDCExtïï«ïºï½ FFDC 259.607 kipïï½ FFDW FNofBm( ) FSuperDWïïºï½ FFDW 38.5 kipïï½ Backward Span Superstructure DC (FBDC) & DW (FBDW): FBDC BNofBm 2ï( ) BSuperDCIntï 2 BSuperDCExtïï«ïºï½ FBDC 259.607 kipïï½ FBDW BNofBm( ) BSuperDWïïºï½ FBDW 38.5 kipïï½ Total Cap Dead Load Weight (TCapDC): CapDC CapDC1 CapL LFoamï( )ï CapDC2 LFoamïï«ïºï½ CapDC 126.979 kipïï½ TCapDC CapDC NofBm( ) BrgSeatDC( )ïï« EarWallDCï«ïºï½ TCapDC 126.979 kipïï½ Total DL on columns including Cap weight (FDC): FDL FFDC FFDWï«ï¨ ï© FBDC FBDWï«ï¨ ï©ï« TCapDCï«ïºï½ FDL 723.194 kipïï½ Column & Drilled Shaft Self Weight: DSahft Length, DsHt 0 ftïïºï½ if Rounded Col, ColDia 0 ftïïºï½ ColDC if ColDia 0ftï¾ Ï 4 ColDia( )2ï HCol( )ï γcïï¬ï wCol bColï HColï γcïï¬ï ï©ïªï« ï¹ïºï»ïºï½ Column Wt, ColDC 52.8 kipïï½ DsDC Ï 4 DsDia( )2ï DsHt( )ï γcïïºï½ Dr Shaft Wt, DsDC 0 kipïï½ Total Dead Load on Drilled Shaft (DL_on_DShaft): DL_on_DShaft FDL NofCol( ) ColDC( )ïï« NofDs( ) DsDC( )ïï«ïºï½ DL_on_DShaft 828.794 kipïï½ Live Load on Drilled Shaft: m 0.85ï½ (Multiple Presence Factors for 3 Lanes) AASHTO LRFDï Tableï 3.6.1.1.2ï 1ï( RLL Lane Truckï«( ) NofLane( )ï m( )ïïºï½ (Total LIVE LOAD without Impact) RLL 277.44 kipïï½ Total Load, DL+LL per Drilled Shaft of Intermediate Bent: Load_on_DShaft DL_on_DShaft RLLï« NofDs ïºï½ Load_on_DShaft 276.6 tonïï½
236 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 5. PRECAST COMPONENT DESIGN Precast Cap Construction and Handling: w1 b hï γcïïºï½ applicable for 0 ftï Lcapï£ 6 ftïï£ w1 3.375 klfïï½ (Cap selfweight) w2 b hï 2 wFoamï hFoamïï( ) γcïïºï½ applicable for 6 ftï Lcapï£ 41 ftïï£ w2 2.471 klfïï½ (Cap selfweight) w3 b hï γcïïºï½ applicable for 41 ftï Lcapï£ 47 ftïï£ w3 3.375 klfïï½ (Cap selfweight) l1 6 ftïïºï½ l2 35 ftïïºï½ l3 6 ftïïºï½ Lcap l1 l2ï« l3ï«ïºï½ (Total Cap Length) Lcap 47 ftïï½ Due to the location of girder bolts, pickup points at 8' from both ends. Indeed, we can model cap lifting points as simply supported beam under self weight supported at 8' and 39' respectively from very end.  l2 = 35 ft l1 = 6 ft l3 = 6 ft lc = 8 ftlb = 31 ft la = 8 ft la 8 ftïïºï½ lb 31 ftïïºï½ lc 8ftïºï½ Construction factor: λcons 1.25ïºï½ λcons 1.25ï½ Maximum Positive Moment (MmaxP) & Negative Moment (MmaxN): Rxn 0.5 w1 l1ï w2 l2ïï« w3 l3ïï«ï¨ ï©ïïºï½ Rxn 63.49 kipïï½ MmaxP Rxn lb 2 ï w1 l1ï l1 2 laï« l1ï lb 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïï w2 2 la l1ï lb 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ 2 ïïïºï½ MmaxP 190.617 kftïï½ MmaxN w1 l1ï l1 2 laï« l1ï ï¦ï§ï¨ ï¶ï·ï¸ï w2 2 la l1ïï¨ ï©2ïï«ïºï½ MmaxN 106.192 kftïï½ Factored Maximum Positive Moment (MuP) & Negative Moment (MuN): MuP λcons MmaxPïïºï½ (Positive Moment at the middle of the cap) MuP 238.271 kftïï½ MuN λcons MmaxNïïºï½ (Negative Moment at the support point) MuN 132.74 kftïï½ Maximum Positive Stress (ftP) & Negative Stress (ftN):
237 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ftP MuP h ycg2ïï¨ ï©ï Icap2 ïºï½ ftP 95.657 psiïï½ ftN MuN ycg2ï Icap2 ïºï½ ftN 52.644 psiïï½ Modulus of Rupture: According PCI hand book 6th edition modulus of rupture, fr = 7.5\/f'c is divided by a safety factor 1.5 in order to design a member without cracking f'c 5 ksiïïºï½ (Compressive Strength of Concrete) Unit weight factor, λ 1ïºï½ fr 5 λï f'c psiïïïºï½ (PCI EQ 5.3.3.2) fr 353.553 psiïï½ fr_check if fr ftPï¾ï¨ ï© fr ftNï¾ï¨ ï©ï "OK"ï¬ï "N.G."ï¬ï ï©ï« ï¹ï»ïºï½ fr_check "OK"ï½ Precast Column Construction and Handling: wCol 4 ftïï½ (Column width) Column breadth, bCol 4 ftïï½ wcol wCol bColï γcïïºï½ (Column self weight) wcol 2.4 klfïï½ Due to the location of girder bolts on column, pickup points at 3' from both ends. Indeed, we can model column lifting points as simply supported beam under self weight supported at 3' and 19' respectively from very end.  w  = 2.4 klf lc = 3 ft lb = 16 ftla = 3 ft la 3 ftïïºï½ lb 16 ftïïºï½ lc 3 ftïïºï½ Maximum Positive Moment (MmaxP) & Negative Moment (MmaxN): MmaxP wcol HColï 2 HCol 4 laïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MmaxP 66 kftïï½ MmaxN wcol la 2ï 2 ïºï½ MmaxN 10.8 kftïï½ Factored Maximum Positive Moment (MuP) & Negative Moment (MuN): MuP λcons MmaxPïïºï½ MuP 82.5 kftïï½ MuN λcons MmaxNïïºï½ MuN 13.5 kftïï½
238 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Scol wCol bCol2ï 6 ïºï½ (Column Section Modulus) Scol 18432 in 3ïï½ Maximum Positive Stress (ftP) & Negative Stress (ftN): ftP MuP Scol ïºï½ ftP 53.711 psiïï½ ftN MuN Scol ïºï½ ftN 8.789 psiïï½ Modulus of Rupture: According PCI hand book 6th edition modulus of rupture, fr = 7.5\/f'c is divided by a safety factor 1.5 in order to design a member without cracking f'c 5 ksiïïºï½ (Compressive Strength of Concrete) Unit weight factor, λ 1ïºï½ fr 5 λï f'c psiïïïºï½ (PCI EQ 5.3.3.2) fr 353.553 psiïï½ fr_check if fr ftPï¾ï¨ ï© fr ftNï¾ï¨ ï©ï "OK"ï¬ï "N.G."ï¬ï ï©ï« ï¹ï»ïºï½ fr_check "OK"ï½ DEVELOPMENT LENGTH: AASHTO LRFD 5.11 Ab 1.56 in 2ïïºï½ (Area of Bar) db 1.41 inïïºï½ (Diameter of Bar) f'c 5 ksiïïºï½ Modification Factor: According to AASHTO LRFD 5.11.2.1.2, the basic development length, ldb is required to multiply by the modification factor to obtain the development length ld for tension or compression. λmod 1.0ïºï½ Basic Tension Development: AASHTO LRFD 5.11.2.1 for bars upto #11 ldb max 1.25 Ab in ï¦ï§ï¨ ï¶ï·ï¸ï fy f'c ksiï ï 0.4 dbï fy ksi ïï¬ï 12 inïï¬ï ï©ïªïªï« ï¹ïº ïºï» ïºï½ (AASHTO LRFD 5.11.2.1.1) ldb 52.324 inïï½ ld λmodï¨ ï© ldbïïºï½ ld 4.36 ftïï½ Basic Compression Development: AASHTO LRFD 5.11.2.2 ldb max 0.63 dbï fyï f'c ksiï 0.3 dbï fy ksi ïï¬ï 8 inïï¬ï ï¦ï§ï§ï¨ ï¶ï· ï·ï¸ ïºï½ AASHTO LRFDï EQï 5.11.2.2.1 1ï 2ï¬ï ( )ï ldb 25.38 inïï½ ld λmodï¨ ï© ldbïïºï½ ld 2.115 ftïï½
239 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ABC SAMPLE CALCULATION â 3b Precast Pier Design for ABC (70â Conventional Pier)
240 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT PRECAST PIER DESIGN FOR ABC (70' SPAN CONVENTIONAL PIER) Nomenclature kip 1000 lbïïºï½ * plf lb ft ïºï½klf kip ft ïºï½ ksi kip in2 ïºï½ psi lb in2 ïºï½ kcf kip ft3 ïºï½ ksf kip ft2 ïºï½ pcf lb ft3 ïºï½ incr 1ïºï½ kft kip ftïïºï½ beam 1ïºï½psf lb ft2 ïºï½ wingwall 1ïºï½ lane 1ïºï½ SlabTh = Thickness of Slab, in BmWt = Weight of Beam per unit length, klf BmSpa = Spacing of beams, ft Haunch = Haunch thickness, in wcap = Width of Abutment/Bent Cap, ft hcap = Depth of Abutment/Bent Cap, ft Railwt =Weight of rail per unit length, klf Ohang = Length of overhang from centreline of the edge beam, ft BmH = height of beam, in BmFlange = Top flange Width of the Beam, in NofCol = Number of Columns per bent DsH = length of Drilled shaft from pt. of fixity to col base, ft DsDia= Shaft diameter, ft ColH = ht of column, ft V= Stream flo velocity, ft/sec Ncomp =Normal wind load component, kip/ft Pcomp= Parallel wind load component, kip/ft BrWidth = Overall Bridge width, ft CapL = Length of Bent cap, ft hâ= superstructure depth below surface of water, ft LatLoad = Wind pressure normal to superstructure, ksf LongLoad= wind pressure parallel to superstructure, ksf Steel 1ïºï½ Concrete 2ïºï½ Nomenclature FNofBm Total Numberï ofï Beamsï inï Forwardï Spanï= BNofBm Total Numberï ofï Beamsï inï Backwardï Spanï= FSpan Forward Spanï Lengthï= BSpan Backward Spanï Lengthï= FDeckW Out toï Outï Forwardï Spanï Deckï Widthï= BDeckW Out toï Outï Backwardï Spanï Deckï Widthï= FBmAg Forward Spanï Beamï Xï Sectionalï Areaï= BBmAg Backward Spanï Beamï Xï Sectionalï Areaï= FBmFlange Forward Spanï Beamï Topï Flangeï Widthï= BBmFlange Backward Spanï Beamï Topï Flangeï Widthï= FHaunch Forward Spanï Haunchï Thicknessï= BHaunch Backward Spanï Haunchï Thicknessï= FBmD Forward Spanï Beamï Depthï orï Heightï= BBmD Backward Spanï Beamï Depthï orï Heightï= FBmIg Forward Spanï Beamï Momentï ofï Inertiaï= BBmIg Backward Spanï Beamï Momentï ofï Inertiaï=
241 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT yFt Forward Spanï Beamï Topï Distanceï fromï cgï= yBt Backward Spanï Beamï Topï Distanceï fromï cgï= NofCol Number ofï Columnsï perï Bentï=SlabTh Slab Thicknessï= NofDs Number ofï Drilledï Shaftï perï Bentï=RailWt Railing Weightï= wCol Width ofï Columnï Sectionï=RailH Railing Heightï= bCol Breadth ofï Columnï Sectionï=RailW Rail Baseï Widthï= DsDia Drilled Shaftï Diameterï=DeckOH Deck Overhangï Distanceï= HCol Height ofï Columnï=DeckW Out toï Outï Deckï Widthï atï Bentï= wEarWall Width ofï Earï Wallï=RoadW Roadway Widthï= hEarWall Height ofï Earï Wallï=BrgTh Bearing Padï Thicknessï Bearing Seatï Thicknessïï«= tEarWall Thickness ofï Earï Wallï=NofLane Number ofï Lanesï= tSWalk Thickness ofï Sideï Walkï=wCap Cap Widthï= bSWalk Breadth ofï Sideï Walkï=hCap Cap Depthï= CapL Cap Lengthï= BmMat Beam Materialï eitherï Steelï orï Concreteï= γc Unit Weightï ofï Concreteï= DiapWt Weight ofï Diaphragmï= wc Unit Weightï ofï Concreteï= γst Unit Weightï ofï Steelï= SlabDCInt Dead Loadï forï Slabï perï Interiorï Beamï= SlabDCExt Dead Loadï forï Slabï perï Exteriorï Beamï= BeamDC Self Weightï ofï Beamï= HaunchDC Dead Loadï ofï Haunchï Concreteï perï Beamï= RailDC Weight ofï Railï perï Beamï= FSuperDCInt Half ofï Forwardï Spanï Superï Structureï Deadï Loadï Componentï perï Interiorï Beamï= FSuperDCExt Half ofï Forwardï Spanï Superï Structureï Deadï Loadï Componentï perï Exteriorï Beamï= FSuperDW Half ofï Forwardï Spanï Overlayï Deadï Loadï Componentï perï Beamï= BSuperDCInt Half ofï Backwardï Spanï Superï Structureï Deadï Loadï Componentï perï Interiorï Beamï= BSuperDCExt Half ofï Backwardï Spanï Superï Structureï Deadï Loadï Componentï perï Exteriorï Beamï= BSuperDW Half ofï Backwardï Spanï Overlayï Deadï Loadï Componentï perï Beamï= TorsionDCInt DeadLoad Torsionï inï aï Capï dueï toï differenceï inï Forwardï andï Backwardï spanï lengthï perï Interiorï Beamï= TorsionDCExt DeadLoad Torsionï inï aï Capï dueï toï differenceï inï Forwardï andï Backwardï spanï lengthï perï Exteriorï Beamï= TorsionDW DW Torsionï inï aï Capï dueï toï differenceï inï Forwardï andï Backwardï spanï lengthï perï Beamï=
242 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT tBrgSeat Thickness ofï Bearingï Seatï= bBrgSeat Breadth ofï Bearingï Seatï=
243 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Note: Use of Light Weight Concrete (LWC) may be considered to reduce the weight of the pier cap instead of using styrofoam blockouts.
244 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT FORWARD SPAN PARAMETER INPUT: FNofBm 12ïºï½ FSpan 70 ftïïºï½ FDeckW 283 6 ftïïºï½ FBmAg 29.1 in2ïïºï½ FBmFlange 10.5 inïïºï½ yFt 14.85 inïïºï½FHaunch 0 inïïºï½ FBmD 29.7 inïïºï½ FBmIg 3990 in4ïïºï½ BACKWARD SPAN PARAMETER INPUT: BNofBm 12ïºï½ BSpan 70 ftïïºï½ BDeckW 283 6 ftïïºï½ BBmAg 29.1 in2ïïºï½ BBmFlange 10.5 inïïºï½ yBt 14.85 inïïºï½BHaunch 0 inïïºï½ BBmD 29.7 inïïºï½ BBmIg 3990 in4ïïºï½ COMMON BRIDGE PARAMETER INPUT: Bent in Question Parameters SlabTh 9 inïïºï½ Overlay 25 psfïïºï½ θ 0 degïïºï½ DeckOH 1.75 ftïïºï½ BrgTh 3.5 inïïºï½ RailWt 0.43 klfïïºï½ RailW 19 inïïºï½ RailH 34.0 inïïºï½ tBrgSeat 0 inïïºï½ bBrgSeat 0 ftïïºï½ DeckW 283 6 ftïïºï½ NofLane 3ïºï½ m 0.85ïºï½ wc 0.150 kcfïïºï½ f'c 5 ksiïïºï½ Cap( ) wCap 4.0 ftïïºï½ hCap 4.0 ftïïºï½ CapL 47 ftïïºï½ NofDs 2ïºï½ DsDia 5 ftïïºï½ wCol 3.5 ftïïºï½ bCol 3.5 ftïïºï½ NofCol 2ïºï½ HCol 22.00 ftïïºï½ f'cs 4 ksiïïºï½ Slab( ) γc 0.150 kcfïïºï½ ebrg 13 inïïºï½ NofBm 12ïºï½ Sta 0.25 ftincrïïºï½ DiapWt 0.2 kipïïºï½ wEarWall 0 ftïïºï½ hEarWall 0 ftïïºï½ tEarWall 0 inïïºï½ IM 0.33ïºï½ BmMat Steelïºï½ Es 29000 ksiïïºï½ γst 490 pcfïïºï½ steel( ) Modulus of elasticity of Concrete: E fcï¨ ï© 33000 wcï¨ ï©1.5ï fc ksiïïïºï½ (AASHTO LRFD EQ 5.4.2.4-1 for K1 = 1) Eslab E f'csï¨ ï©ïºï½ Eslab 3834.254 ksiïï½ Ecap E f'cï¨ ï©ïºï½ Ecap 4286.826 ksiïï½ Modulus of Beam or Girder: Input Beam Material, BmMat = Steel or Concrete Ebeam if BmMat Steel= Esï¬ï E f'cï¨ ï©ï¬ï ï¨ ï©ïºï½ Ebeam 29000 ksiïï½
245 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 1. BENT CAP LOADING DEAD LOAD FROM SUPERSTRUCTURE: The permanent dead load components (DC) consist of slab, rail, sidewalk, haunch weight and beam self weight. Slab Dead weight components will be distributed to each beam by slab tributary width between beams. Interior Beam tributary width (IntBmTriW) is taken as the average of consecutive beam spacing for a particular interior beam. Exterior Beam tributary width (ExtBmTriW) is taken as half of beam spacing plus the overhang distance. Rail, sidewalk dead load components and future wearing surface weight components (DW) can be distributed evenly among each beam. Half of DC and DW components from forward span and backward span comprise the total superstructure load or dead load reaction per beam on the pier cap or the bent cap. FORWARD SPAN SUPERSTRUCTURE DEAD LOAD: consists of 12 W30x99 Beams 12 beams were spaced 4.5' and 3'-4" alternately in forward span. For beam spacing see Typical Section Details sheet FBmSpa1 4.5 ftïïºï½ FBmSpa2 10 3 ftïïºï½ FIntBmTriW FBmSpa1 2 FBmSpa2 2 ï«ïºï½ FIntBmTriW 3.917 ftïï½ FExtBmTriW FBmSpa1 2 DeckOHï«ïºï½ FExtBmTriW 4 ftïï½ RoadW 0.25 FDeckW 3 DeckWïï«( )ï 2 RailWïïïºï½ RoadW 44 ftïï½ SlabDCInt γc FIntBmTriWï SlabThï FSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ SlabDCInt 15.422 kip beam ïï½ SlabDCExt γc FExtBmTriWï SlabThï FSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ SlabDCExt 15.75 kip beam ïï½ BeamDC γst FBmAgï FSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ BeamDC 3.466 kip beam ïï½ HaunchDC γc FHaunchï FBmFlangeï FSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ HaunchDC 0 kip beam ïï½ NOTE: Permanent loads such as the weight of the Rail (Barrier), Future wearing surface may be distributed uniformly among all beams if following conditions are met. Apply for live load distribution factors too. AASHTO LRFD 4.6.2.2.1 1. Width of deck is constant 2. Number of Beams >= 4 beams 3. Beams are parallel and have approximately same stiffness 4. The Roadway part of the overhang, de<= 3ft 5. Curvature in plan is < 4o 6. Bridge cross-section is consistent with one of the x-section shown in AASHTO LRFD TABLE 4.6.2.2.1-1 RailDC 2 RailWtï FNofBm FSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ RailDC 2.508 kip beam ïï½
246 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT OverlayDW RoadW Overlayï FNofBm FSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ OverlayDW 3.208 kip beam ïï½ Forward Span Superstructure DC & DW per Interior and Exterior Beam: FSuperDCInt RailDC BeamDCï« SlabDCIntï« HaunchDCï« DiapWtï«ïºï½ FSuperDCInt 21.596 kip beam ïï½ FSuperDCExt RailDC BeamDCï« SlabDCExtï« HaunchDCï« 0.5 DiapWtïï«ïºï½ FSuperDCExt 21.824 kip beam ïï½ FSuperDW OverlayDWïºï½ FSuperDW 3.208 kip beam ïï½ BACKWARD SPAN SUPERSTRUCTURE DEAD LOAD: consists of 12 W30x99 beams 12 beams were spaced 4.5' and 3'-4" alternately in Backward span. For beam spacing see Typical Section Details sheet BBmSpa1 4.5 ftïïºï½ BBmSpa2 10 3 ftïïºï½ BIntBmTriW BBmSpa1 2 BBmSpa2 2 ï«ïºï½ BIntBmTriW 3.917 ftïï½ BExtBmTriW BBmSpa1 2 DeckOHï«ïºï½ BExtBmTriW 4 ftïï½ RoadW 0.25 BDeckW 3 DeckWïï«( )ï 2 RailWïïïºï½ RoadW 44 ftïï½ SlabDCInt γc BIntBmTriWï SlabThï BSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ SlabDCInt 15.422 kip beam ïï½ SlabDCExt γc BExtBmTriWï SlabThï BSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ SlabDCExt 15.75 kip beam ïï½ BeamDC γst BBmAgï BSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ BeamDC 3.466 kip beam ïï½ HaunchDC γc BHaunchï BBmFlangeï BSpan2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ HaunchDC 0 kip beam ïï½ RailDC 2 RailWtï BNofBm BSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ RailDC 2.508 kip beam ïï½ OverlayDW RoadW Overlayï BNofBm BSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ OverlayDW 3.208 kip beam ïï½ Total Backward Span Superstructure DC & DW per Interior and Exterior Beam: BSuperDCInt RailDC BeamDCï« SlabDCIntï« HaunchDCï« DiapWtï«ïºï½ BSuperDCInt 21.596 kip beam ïï½ BSuperDCExt RailDC BeamDCï« SlabDCExtï« HaunchDCï« 0.5 DiapWtïï«ïºï½ BSuperDCExt 21.824 kip beam ïï½
247 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT BSuperDW OverlayDWïºï½ BSuperDW 3.208 kip beam ïï½ Total Superstructure DC & DW Reactions per Beam on Bent Cap: SuperDCInt FSuperDCInt BSuperDCIntï«ïºï½ SuperDCInt 43.192 kip beam ïï½ SuperDCExt FSuperDCExt BSuperDCExtï«ïºï½ SuperDCExt 43.648 kip beam ïï½ SuperDW FSuperDW BSuperDWï«ïºï½ SuperDW 6.417 kip beam ïï½ TorsionDCInt max FSuperDCInt BSuperDCIntï¬ï ï¨ ï© min FSuperDCInt BSuperDCIntï¬ï ï¨ ï©ïï¨ ï© ebrgïïºï½ TorsionDCInt 0 kftbeamïï½ TorsionDCExt max FSuperDCExt BSuperDCExtï¬ï ï¨ ï© min FSuperDCExt BSuperDCExtï¬ï ï¨ ï©ïï¨ ï© ebrgïïºï½ TorsionDCExt 0 kftbeamïï½ TorsionDW max FSuperDW BSuperDWï¬ï ( ) min FSuperDW BSuperDWï¬ï ( )ï( ) ebrgïïºï½ TorsionDW 0 kft beam ïï½ CAP, EAR WALL & BEARING SEAT WEIGHT: The bent cap has only one solid section along the length. The solid rectangular section of 4'X4' can be seen in typical section and pier elevation figure. CapDC is the weight of the section of the bent or pier cap. CapDC wCap hCapï γcïïºï½ CapDC 2.4 klfïï½ CapDCsta wCap hCapï γcïï¨ ï© Sta( )ïïºï½ CapDCsta 0.6 kipincrïï½ EarWallDC wEarWall hEarWallï tEarWallï( ) γcïïºï½ EarWallDC 0 kipïï½ BrgSeatDC tBrgSeat bBrgSeatï wCap( )ï γcïïºï½ BrgSeatDC 0 kipbeamïï½ EIcap Ecap wCap hCap3ï 12 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ EIcap 1.317 10 7ï´ kip ft2ïïï½ Distribution Factor RESULTS OF DISTRIBUTION FACTORS: Forward Span Distribution Factors: DFMFmax 0.391ï½ (Distribution Factor for Moment) DFSFmax 0.558ï½ (Distribution Factor for Shear) Backward Span Distribution Factors:
248 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT DFMBmax 0.391ï½ (Distribution Factor for Moment) DFSBmax 0.558ï½ (Distribution Factor for Shear) LIVE LOAD FOR SIMPLY SUPPORTED BRIDGE: HL-93 Loading: According to AASHTO LRFD 3.6.1.2.1 HL-93, consists of Design Truck + Design Lane Load or Design Tandem + Design Lane Load. Design Truck rather than Design Tandem + Design Lane Load controls the maximum Live Load Reactions at an interior bent for a span longer than 26'. For maximum reaction, place middle axle (P2 = 32 kip) of design truck over the support at a bent between the forward and the backward span and place rear axle (P3 = 32 kip) 14' away from P2 on the longer span while placing P1 14' away from P1 on either spans yielding maximum value. P1 Front Axleï ofï Designï Truckï= P2 Middle Axleï ofï Designï Truckï= P3 Rear Axleï ofï Designï Truckï= Design Truck Axle Load: P1 8 kipïïºï½ P2 32 kipïïºï½ P3 32 kipïïºï½ AASHTO LRFDï 3.6.1.2.2ï( ) TruckT P1 P2ï« P3ï«ïºï½ Design Lane Load: wlane 0.64 klfïïºï½ AASHTO LRFDï 3.6.1.2.4ï( ) Longer Span Length, Llong max FSpan BSpanï¬ï ( )ïºï½ Shorter Span Length, Lshort min FSpan BSpanï¬ï ( )ïºï½ Lane Load Reaction: Lane wlane Llong Lshortï« 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Lane 44.8 kip lane ïï½ Truck Load Reaction: Truck P2 P3 Llong 14ftïï¨ ï© Llong ïï« P1 max Llong 28ftïï¨ ï© Llong Lshort 14ftïï¨ ï© Lshort ï¬ï ï©ïª ï« ï¹ïº ï» ïï«ïºï½ Truck 64 kip lane ïï½ Maximum Live Load Reaction with Impact (LLRxn) over support on Bent: The Dynamic Load Allowance or Impact Factor, IM 0.33ï½ AASHTO LRFDï Tableï 3.6.2.1ï 1ï( ) LLRxn Lane Truck 1 IMï«( )ïï«ïºï½ LLRxn 129.92 kip lane ïï½ Live Load Model for Cap Loading Program: AASHTO LRFD Recommended Live Load Model For Cap Loading Program: Live Load reaction on the pier cap using distribution factors are not sufficient to design bent cap for moment and shear. Therefore, the reaction from live load is uniformly distributed to over a 10' width (which becomes W) and the reaction from the truck is applied as two concentrated loads (P and P) 6' apart. The loads act within a 12' wide traffic lane. The reaction W and the truck move across the width of the traffic lane. However, neither of the P loads can be placed closer than 2' from the edge of the traffic lane. One lane, two lane, three lane and so forth loaded traffic can be moved across the width of the roadway to create maximum load effects. Load on one rear wheel out of rear axle of the truck with Impact: P 0.5 P3ïï¨ ï© 1 IMï«( )ïïºï½ P 21.28 kipïï½ The Design Lane Load Width Transversely in a Lane wlaneTransW 10 ftïïºï½ AASHTO LRFD Article 3.6.1.2.1 The uniform load portion of the Live Load, kip/station for Cap Loading Program:
249 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT W LLRxn 2 Pïï( ) Staï wlaneTransW ïºï½ W 2.184 kip incr ïï½ LOADS generated above will be placed into a CAP LOADING PROGRAM to obtain moment and shear values for Bent Cap design. Torsion on Bent Cap per Beam and per Drilled Shaft: Torsional load about center line of bent cap occurs due to horizontal loads acting on the superstructure perpendicular to the bent length or along the bridge length. Braking force, Centrifugal force, WS on superstructure, and WL cause torsion on bent. In addition, torque about center line of bent cap for the dead load reaction on beam brg location occurs due to differences in forward and backward span length and eccentricity between center line of bent cap and brg location. Torsion can be neglected if Tu<0.25ï¦Tcr (AASHTO LRFD 5.8.2.1) The maximum torsional effects on the pier cap will be obtained from RISA frame analysis under loading as stated in AASHTO LRFD SECTION 3 for different load combinations using AASHTO LRFD Table 3.4.1-1
250 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 2. BENT CAP FLEXURAL DESIGN FLEXURAL DESIGN OF BENT CAP: h( ) b( ) f'c 5.0 ksiïïºï½ fy 60 ksiïïºï½ Es 29000 ksiïïºï½ Ïm 0.9ïºï½ Ïv 0.9ïºï½ Ïn 1ïºï½ γc 0.150 kcfïïºï½ bcover 2.5 inïïºï½ tcover 2.5 inïïºï½ h 4.0 ftïïºï½ b 4.0 ftïïºï½ Ec Ecapïºï½ OUTPUT of BENT CAP LOADING PROGRAM: The maximum load effects from different applicable limit states: DEAD LOAD MdlPos 627.2 kftïïºï½ MdlNeg 783.4 kftïïºï½ SERVICE I MsPos 1462.5 kftïïºï½ MsNeg 1297.7 kftïïºï½ STRENGTH I MuPos 1900.5 kftïïºï½ MuNeg 2262.8 kftïïºï½
251 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT FLEXURE DESIGN: Minimum Flexural Reinforcement AASHTO LRFD 5.7.3.3.2 Factored Flexural Resistance, Mr, must be greater than or equal to the lesser of 1.2Mcr or 1.33 Mu. Applicable to both positive and negative moment. Modulus of rupture fr 0.37 f'c ksiïïºï½ (AASHTO LRFD EQ 5.4.2.6) fr 0.827 ksiïï½ S b h2ï 6 ïºï½ (Section Modulus) S 18432 in3ïï½
252 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Cracking moment Mcr S frïïºï½ (AASHTO LRFD EQ 5.7.3.3.2-1) Mcr 1270.802 kip ftïïï½ Mcr1 1.2 Mcrïïºï½ Mcr1 1524.963 kip ftïïï½ Mcr2 1.33 max MuPos MuNegï¬ï ï¨ ï©ïïºï½ Mcr2 3009.524 kip ftïïï½ Mcr_min min Mcr1 Mcr2ï¬ï ï¨ ï©ïºï½ Therefore Mr must be greater than Mcr_min 1524.963 kip ftïïï½ Moment Capacity Design (Positive Moment, Bottom Bars B) AASHTO LRFD 5.7.3.2 Bottom Steel arrangement for the Cap: Input no. of total rebar in a row from bottom of cap up to 12 rows (in unnecessary rows input zero) Np 5 5 0 0 0 0 0 0 0 0 0 0( )ïºï½ Input area of rebar corresponding to above rows from bottom of cap, not applicable for mixed rebar in a single row Abp 1.56 1.56 0 0 0 0 0 0 0 0 0 0( ) in 2ïïºï½ Input center to center vertical distance between each rebar row starting from bottom of cap clp 3.5 4 0 0 0 0 0 0 0 0 0 0( ) inïïºï½ dc Calc for Pos Moment nsPos 2ï½ (No. of Bottom or Positive Steel Layers) Distance from centroid of positive rebar to extreme bottom tension fiber (dcPos): dcPos Ayp0 0ï¬ï ï¨ ï© inïïºï½ dcPos 5.5 inïï½ Effective depth from centroid of bottom rebar to extreme compression fiber (dPos): dPos h dcPosïïºï½ dPos 42.5 inïï½ Compression Block depth under ultimate load AASHTO LRFD 5.7.2.2 β1 min 0.85 max 0.65 0.85 0.05ksi f'c 4 ksiïïï¨ ï©ïï¬ï ï©ïªï« ï¹ïºï»ï¬ï ï©ïªï« ï¹ïºï»ïºï½ β1 0.8ï½ The Amount of Bottom or Positive Steel As Required, b 48 inïï½ AsReq 0.85 f'cï bï dPosï fy ï¦ï§ ï¨ ï¶ï· ï¸ 1 1 2 MuPosï 0.85 Ïmï f'cï bï dPos2ï ïï ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ïïºï½ AsReq 10.305 in 2ïï½ The Amount of Positive As Provided,
253 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT NofBarsPos Npï¥ïºï½ NofBarsPos 10ï½ AsPos Ayp0 1ï¬ï ï¨ ï© in2ïïºï½ AsPos 15.6 in2ïï½ Compression depth under ultimate load cPos AsPos fyï 0.85 f'cï β1ï bï ïºï½ (AASHTO LRFD EQ 5.7.3.1.1-4) cPos 5.735 inïï½ aPos β1 cPosïïºï½ (AASHTO LRFD 5.7.3.2.2) aPos 4.588 inïï½ Nominal flexural resistance: MnPos AsPos fyï dPos aPos 2 ïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ (AASHTO LRFD EQ 5.7.3.2.2-1) MnPos 3136.059 kip ftïïï½ Tension controlled resistance factor for flexure ÏmPos min 0.65 0.15 dPos cPos 1ïï¦ï§ ï¨ ï¶ï· ï¸ ïï« 0.9ï¬ï ï©ïª ï« ï¹ïº ï» ïºï½ (AASHTO LRFD EQ 5.5.4.2.1-2) ÏmPos 0.9ï½ or simply use, Ïm 0.9ï½ (AASHTO LRFD 5.5.4.2) MrPos ÏmPos MnPosïïºï½ (AASHTO LRFD EQ 5.7.3.2.1-1) MrPos 2822.453 kip ftïïï½ MinReinChkPos if MrPos Mcr_minï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ MinReinChkPos "OK"ï½ UltimateMomChkPos if MrPos MuPosï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ UltimateMomChkPos "OK"ï½ Moment Capacity Design (Negative Moment, Top Bars A) AASHTO LRFD 5.7.3.2 Top Steel arrangement for the Cap: Input no. of total rebar in a row from top of cap up to 12 rows (in unnecessary rows input zero) Nn 8 0 0 0 0 0 0 0 0 0 0 0( )ïºï½ Input area of rebar corresponding to above rows from top of cap, not applicable for mixed rebar in a single row Abn 1.56 0 0 0 0 0 0 0 0 0 0 0( ) in 2ïïºï½ Input center to center vertical distance between each rebar row starting from top of cap cln 3.5 0 0 0 0 0 0 0 0 0 0 0( ) inïïºï½ dc Calc for Neg. Moment
254 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT nsNeg 1ï½ (No. of Negative or Top Steel Layers) Distance from centroid of negative rebar to top extreme tension fiber (dcNeg): dcNeg Ayn0 0ï¬ï ï¨ ï© inïïºï½ dcNeg 3.5 inïï½ Effective depth from centroid of top rebar to extreme compression fiber (dNeg): dNeg h dcNegïïºï½ dNeg 44.5 inïï½ The Amount of Negative As Required, AsReq 0.85 f'cï bï dNegï fy ï¦ï§ ï¨ ï¶ï· ï¸ 1 1 2 MuNegï 0.85 Ïmï f'cï bï dNeg2ï ïï ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ïïºï½ AsReq 11.757 in 2ïï½ The Amount of Negative As Provided, NofBarsNeg Nnï¥ïºï½ NofBarsNeg 8ï½ AsNeg Ayn0 1ï¬ï ï¨ ï© in2ïïºï½ AsNeg 12.48 in2ïï½ Compression depth under ultimate load cNeg AsNeg fyï 0.85 f'cï β1ï bï ïºï½ cNeg 4.588 inïï½ aNeg β1 cNegïïºï½ aNeg 3.671 inïï½ Thus, nominal flexural resistance: MnNeg AsNeg fyï dNeg aNeg 2 ïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MnNeg 2662.278 kip ftïïï½ MrNeg Ïm MnNegïïºï½ (Factored flexural resistance) MrNeg 2396.05 kip ftïïï½ MinReinChkNeg if MrNeg Mcr_minï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ MinReinChkNeg "OK"ï½ UltimateMomChkNeg if MrNeg MuNegï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ UltimateMomChkNeg "OK"ï½ Control of Cracking at Service Limit State AASHTO LRFD 5.7.3.4 exposure_cond 1ïºï½ (for exposure condition, input Class 1 = 1 and Class 2 = 2) γe if exposure_cond 1= 1ï¬ï 0.75ï¬ï ( )ïºï½ (Exposure condition factor) γe 1ï½ sidecTop sidecBotï¨ ï© 4.75 4.75( ) inïïºï½ (Input side cover for Top and Bottom Rebars) Positive Moment (Bottom Bars B) To find Smax: S is spacing of first layer of rebar closest to tension face
255 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT n round Es Ec 0ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ (modular ratio) (AASHTO LRFD 5.7.1) n 7ï½ ÏPos AsPos b dPosï ïºï½ ÏPos 0.0076ï½ kPos ÏPos nï 1ï«ï¨ ï©2 1ï ÏPos nïïïºï½ (Applicable for Solid Rectangular Section) kPos 0.278ï½ jPos 1 kPos 3 ïïºï½ jPos 0.907ï½ fssPos MsPos AsPos jPosï dPosï ïºï½ fssPos 29.174 ksiïï½(Tensile Stress at Service Limit State) dc1Pos clp0 0ï¬ï ïºï½ (Distance of bottom first row rebar closest to tension face) dc1Pos 3.5 inïï½ Î²sPos 1 dc1Pos 0.7 h dc1Posïï¨ ï©ïï«ïºï½ βsPos 1.112ï½ smaxPos 700 kip in γeï βsPos fssPosï 2 dc1Posïïïºï½ AASHTO LRFD EQ (5.7.3.4-1) smaxPos 14.57 inïï½ sActualPos b 2 sidecBotïï Np0 0ï¬ï 1ïïºï½ (Equal horizontal spacing of Bottom first Rebar row closest to Tension Face) sActualPos 9.625 inïï½ Actual Max Spacing in Bottom first Layer, saPosProvided 7 inïïºï½ sActualPos max saPosProvided sActualPosï¬ï ï¨ ï©ïºï½ sActualPos 9.625 inïï½ SpacingCheckPos if smaxPos sActualPosï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ SpacingCheckPos "OK"ï½ Negative Moment (Top Bars A) ÏNeg AsNeg b dNegï ïºï½ ÏNeg 0.006ï½ kNeg ÏNeg nï 1ï«ï¨ ï©2 1ï ÏNeg nïïïºï½ (Applicable for Solid Rectangular Section) kNeg 0.248ï½ jNeg 1 kNeg 3 ïïºï½ jNeg 0.917ï½
256 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT fssNeg MsNeg AsNeg jNegï dNegï ïºï½ fssNeg 30.567 ksiïï½ dc1Neg cln0 0ï¬ï ïºï½ (Distance of Top first layer rebar closest to tension face) dc1Neg 3.5 inïï½ Î²sNeg 1 dc1Neg 0.7 h dc1Negïï¨ ï©ïï«ïºï½ βsNeg 1.112ï½ smaxNeg 700 kip in γeï βsNeg fssNegï 2 dc1Negïïïºï½ smaxNeg 13.587 inïï½ sActualNeg b 2 sidecTopïï Nn0 0ï¬ï 1ïïºï½ (Equal horizontal spacing of top first Rebar row closest to Tension Face) sActualNeg 5.5 inïï½ Actual Max Spacing Provided in Top first row closest to Tension Face, saNegProvided 11.125 inïïºï½ sActualNeg max saNegProvided sActualNegï¬ï ï¨ ï©ïºï½ sActualNeg 11.125 inïï½ SpacingCheckNeg if smaxNeg sActualNegï³ï¨ ï© "OK"ï¬ï "NG"ï¬ï ï©ï« ï¹ï»ïºï½ SpacingCheckNeg "OK"ï½ SUMMARY OF FLEXURE DESIGN: Bottom Rebar or B Bars: use 10~#11 bars @ 5 bars in each row of 2 rows Top Rebar or A Bars: use 8~#11 bars @ 8 bars in top row SKIN REINFORCEMENT (BARS T) AASHTO LRFD 5.7.3.4 SkBarNo 5ïºï½ (Size of a skin bar) Area of a skin bar, AskBar 0.31 in 2ïïºï½ dcTop clnï¥ïºï½ dcTop 3.5 inïï½ dcBot clpï¥ïºï½ dcBot 7.5 inïï½ Effective Depth from centroid of Extreme Tension Steel to Extreme compression Fiber (dl): dl max h clp0 0ï¬ï ï h cln0 0ï¬ï ïï¬ï ï¨ ï©ïºï½ dl 44.5 inïï½ Effective Depth from centroid of Tension Steel to Extreme compression Fiber (de):
257 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT de max dPos dNegï¬ï ï¨ ï©ïºï½ de 44.5 inïï½ As min AsNeg AsPosï¬ï ï¨ ï©ïºï½ min. of negative and positive reinforcement As 12.48 in2ïï½ dskin h dcTop dcBotï«ï¨ ï©ïïºï½ dskin 37 inïï½ Skin Reinforcement Requirement: AASHTO LRFD EQ 5.7.3.4-2 AskReq if dl 3ftï¾ min 0.012 in ft ï dl 30 inïïï¨ ï©ï dskinï As Apsï«4ï¬ï ï©ïªï« ï¹ïºï»ï¬ï 0in 2ï¬ï ï©ïªï« ï¹ïºï»ïºï½ AskReq 0.537 in 2ïï½ NoAskbar1 R AskReq AskBar ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ NoAskbar1 2ï½ per Side Maximum Spacing of Skin Reinforcement: SskMax min de 6 12 inïï¬ï ï¦ï§ï¨ ï¶ï·ï¸ïºï½ AASHTO LRFD 5.7.3.4 SskMax 7.417 inïï½ NoAskbar2 if dl 3ftï¾ R dskin SskMax 1ïï¦ï§ ï¨ ï¶ï· ï¸ ï¬ï 1ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ NoAskbar2 4ï½ per Side NofSideBarsreq max NoAskbar1 NoAskbar2ï¬ï ï¨ ï©ïºï½ NofSideBarsreq 4ï½ SskRequired dskin 1 NofSideBarsreqï« ïºï½ SskRequired 7.4 inïï½ NofSideBars 4ïºï½ (No. of Side Bars Provided) SskProvided dskin 1 NofSideBarsï«ïºï½ SskProvided 7.4 inïï½ SskChk if SskProvided SskMaxï¼ "OK"ï¬ï "N.G."ï¬ï ï¨ ï©ïºï½ SskChk "OK"ï½ Therefore Use: NofSideBars 4ï½ and Size SkBarNo 5ï½
258 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 3. BENT CAP SHEAR AND TORSION DESIGN SHEAR DESIGN OF CAP: Effective Shear Depth, dv max de a 2 ï 0.9 deï 0.72 hï ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ = (AASHTO LRFD 5.8.2.9) dv Distance betweenï theï resultantsï ofï tensileï andï compressiveï Forceï= ds Effective depthï fromï cgï ofï theï nonprestressedï tensileï steelï toï extremeï compressionï fiberï= dp Effective depthï fromï cgï ofï theï prestressedï tendonï toï extremeï compressionï fiberï= de Effective depthï fromï centroidï ofï theï tensileï forceï toï extremeï compressionï fiberï atï criticalï shearï Locationï= θ Angle ofï inclinationï diagonalï compressiveï stressï= Ao Area enclosedï byï shearï flowï pathï includingï areaï ofï holesï thereinï= Ac Area ofï concreteï onï flexuralï tensionï sideï ofï memberï shownï inï AASHTOï LRFDï Figureï 5.8.3.4.2ï 1ï= Aoh Area enclosedï byï centerlineï ofï exteriorï closedï transverseï torsionï reinforcementï includingï areaï ofï holesï thereinï= Total Flexural Steel Area, As AsNegïºï½ As 12.48 in 2ïï½ Nominal Flexure, Mn MnNegïºï½ Mn 2662.278 kftïï½ Stress block Depth, a aNegïºï½ a 3.671 inïï½ Effective Depth, de dNegïºï½ de 44.5 inïï½ Effective web Width at critical Location, bv bïºï½ bv 4 ftïï½ Input initial ï±ï¬ θ 35 degïïºï½ cotθ cot θ( )ïºï½ Shear Resistance Factor, Ïv 0.9ïºï½
259 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Cap Depth & Width, h 48 inïï½ b 48 inïï½ Moment Arm, de a 2 ïï¦ï§ï¨ ï¶ï·ï¸ 42.665 inïï½ 0.9 deï 40.05 inïï½ 0.72 hï 34.56 inïï½ Effective Shear Depth at Critical Location, dv max de a 2 ï 0.9 deï 0.72 hï ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ ï¦ï§ ï§ ï§ ï§ï¨ ï¶ï· ï· ï· ï·ï¸ ïºï½ (AASHTO LRFD 5.8.2.9) dv 42.665 inïï½ hh h tcoverï bcoverïïºï½ (Height of shear reinforcement) hh 43 inïï½ bh b 2 bcoverïïïºï½ (Width of shear reinforcement) bh 43 inïï½ ph 2 hh bhï«ï¨ ï©ïºï½ (Perimeter of shear reinforcement) ph 172 inïï½ Aoh hhï¨ ï© bhï¨ ï©ïïºï½ (Area enclosed by the shear reinforcement) Aoh 1849 in2ïï½ Ao 0.85 Aohïïºï½ (AASHTO LRFD C5.8.2.1) Ao 1571.65 in 2ïï½ Ac 0.5 bï hïïºï½ AASHTO LRFDï FIGUREï 5.8.3.4.2ï 1ï( ) Ac 1152 in 2ïï½ Yield strength & Modulus of Elasticity of Steel Reinforcement: fy Esï¨ ï© 60 29000( ) ksiïïºï½ AASHTO LRFDï 5.4.3.1ï 5.4.3.2ï¬ï ( ) Input Mu, Tu, Vu, Nu for the critical section to be investigated: (Loads from Bent Cap & RISA Analysis) Mu Tuï¨ ï© 1398.6 570.2( ) kftïïºï½ Vu Nuï¨ ï© 463.4 0( ) kipïïºï½ M'u max Mu Vu Vpï dvïï¬ï ï¨ ï©ïºï½ AASHTO LRFD B5.2 M'u 1647.569 kip ftïïï½ V'u Vu 2 0.9 phï Tuï 2 Aoï ï¦ï§ ï¨ ï¶ï· ï¸ 2 ï«ïºï½ (Equivalent shear) AASHTO LRFD EQ (5.8.2.1-6) for solid section V'u 572.966 kipïï½ Assuming atleastï minimumï transverseï reinforcementï isï providedï (Always provide min. transverse reinf.) εx M'u dv ï¦ï§ ï¨ ï¶ï· ï¸ 0.5 Nuïï« 0.5 V'u Vpïï¨ ï©ï cotθïï« Aps fpoïï 2 Es Asï Ep Apsïï«ï¨ ï©ï= (Strain from Appendix B5) AASHTO LRFD EQ (B5.2-1)
260 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT vu Vu Ïv Vpïïï¨ ï© Ïv bvï dvï ïºï½ (Shear Stress) AASHTO LRFD EQ (5.8.2.9-1) vu 0.251 ksiïï½ r max 0.075 vu f'c ï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ (Shear stress ratio) r 0.075ï½ Determining Beta & Theta After Interpolating the value of Î Î( ) Î 36.4 degïï½ Î 2.23ï½ Nominal Shear Resistance by Concrete, Vc 0.0316 Îï f'c ksiïï bvï dvïïºï½ AASHTO LRFD EQ (5.8.3.3-3) Vc 322.7 kipïï½ Vu 463.4 kipïï½ 0.5 Ïvï Vc Vpï«ï¨ ï©ï 145.211 kipïï½ REGION REQUIRING TRANSVERSE REINFORCEMENT: AASHTO LRFD 5.8.2.4 Vu 0.5 Ïvï Vc Vpï«ï¨ ï©ïï¾ AASHTO LRFD EQ (5.8.2.4-1) check if Vu 0.5 Ïvï Vc Vpï«ï¨ ï©ïï¾ "Provide Shear Reinf"ï¬ï "No reinf."ï¬ï ï©ï« ï¹ï»ïºï½ check "Provide Shear Reinf"ï½ Vn min Vc Vsï« Vpï« 0.25 f'cï bvï dvï Vpï« ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ = (Nominal Shear Resistance) AASHTO LRFDï EQï 5.8.3.3 1ï 2ï¬ï ( )ï Vs Av fyï dvï cotθ cotαï«( )ï sinαï S = (Shear Resistance of Steel) AASHTO LRFDï EQï 5.8.3.3 4ï( )ï Vs Av fyï dvï cotθï S = Shear Resistanceï ofï Steelï whenï α 90 degï=ï¬ï ( ) AASHTO LRFD EQ (C5.8.3.3-1) Sv 9 inïïºï½ (Input Stirrup Spacing) Vp 0 kipïï½ Vu Vcï¨ ï© 463.4 322.691( ) kipïï½ fy 60 ksiïï½ dv 42.665 inïï½ Î 36.4 degïï½ (Derive from AASHTO LRFD EQ 5.8.3.3-1, C5.8.3.3-1 and ï¦Vn >= Vu)Av_req Vu Ïv Vcï Vpï ï¦ï§ ï¨ ï¶ï· ï¸ Sv fy dvï cotÎï ï¦ï§ ï¨ ï¶ï· ï¸ ïïºï½ Av_req 0.4982 in 2ïï½ Torsional Steel:
261 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT At Tu 2 Ïvï Aoï fyï cotÎï Svïïºï½ (Derive from AASHTO LRFD EQ 5.8.3.6.2-1 and ï¦Tn >= Tu) At 0.267 in 2ïï½ Avt_req Av_req 2 Atïï«ïºï½ Shear Torsionï«( ) Avt_req 1.033 in 2ïï½ Avt 4 0.44 in 2ïï¨ ï©ïïºï½ (Use 2 #6 double leg Stirrup at Sv c/c,) Provided, Avt 1.76 in2ïï½ Avt_check if Avt Avt_reqï¾ "OK"ï¬ï "NG"ï¬ï ï¨ ï©ïºï½ Avt_check "OK"ï½ Maximum Spacing Check: AASHTO LRFDï Articleï 5.8.2.7ï Vu 463.4 kipïï½ 0.125 f'cï bvï dvï 1279.94 kipïï½ Svmax if Vu 0.125 f'cï bvï dvïï¼ min 0.8 dvï 24 inïï¬ï ï¨ ï©ï¬ï min 0.4 dvï 12 inïï¬ï ï¨ ï©ï¬ï ï¨ ï©ïºï½ Svmax 24 inïï½ Svmax_check if Sv Svmaxï¼ "OK"ï¬ï "use lower spacing"ï¬ï ï¨ ï©ïºï½ Svmax_check "OK"ï½ Av Avt Atïïºï½ (Shear Reinf. without Torsion Reinf.) Av 1.493 in 2ïï½ Vs Av fyï dvï cotÎï Sv ïºï½ Vs 575.804 kipïï½ Minimum Transverse Reinforce Check: AASHTO LRFDï Articleï 5.8.2.5ï bv 48 inïï½ Avmin 0.0316 f'c ksiïï bv Svï fy ïïºï½ AASHTO LRFDï EQï 5.8.2.5 1ï( )ï Avmin 0.509 in 2ïï½ Avmin_check if Avt Avminï¾ "OK"ï¬ï "NG"ï¬ï ï¨ ï©ïºï½ Avmin_check "OK"ï½ Maximum Nominal Shear: To ensure that the concrete in the web of beam will not crush prior to yield of shear reinforcement, LRFD Specification has given an upper limit of 0.25 f'cï bvï dvï Vpï« 2559.882 kipïï½ Vc Vsï« Vpï« 898.495 kipïï½ Vn min Vc Vsï« Vpï« 0.25 f'cï bvï dvï Vpï« ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ï¦ï§ ï§ï¨ ï¶ï· ï·ï¸ ïºï½ AASHTO LRFDï EQï 5.8.3.3 1ï 2ï¬ï ( )ï Vn 898.495 kipïï½ Ïv Vnï 808.645 kipïï½ Vu 463.4 kipïï½ ÏVn_check if Ïv Vnï Vuï¾ "OK"ï¬ï "NG"ï¬ï ï¨ ï©ïºï½ ÏVn_check "OK"ï½ Torsional Resistance,
262 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Tn 2 Aoï 0.5 Avtïï¨ ï©ï fyï cotÎï Sv ïºï½ AASHTO LRFDï EQï 5.8.3.6.2 1ï( )ï Ïv Tnï 1875.9 kip ftïïï½ Longitudinal Reinforcement Requirements including Torsion: AASHTO LRFDï 5.8.3.6.3ï AASHTO LRFDï EQ 5.8.3.6.3 1ï( )ï Applicable for solid section with Torsion Aps fpsï As fyïï« M'u Ïm dvï ï¦ï§ ï¨ ï¶ï· ï¸ 0.5 Nuï Ïn ï« cotÎ VuÏv Vpï 0.5 V'sïï ï¦ï§ ï¨ ï¶ï· ï¸ 2 0.45 phï Tuï 2 Ïvï Aoï ï¦ï§ ï¨ ï¶ï· ï¸ 2 ï«ïï«ï³ Ïm Ïv Ïnï¨ ï© 0.9 0.9 1( )ïºï½ As fyï Aps fpsïï« 748.8 kipïï½ M'u 1647.569 kip ftïïï½ Vu 463.4 kipïï½ Nu 0 kipïï½ Vs 575.804 kipïï½ Tu 570.2 kip ftïïï½ ph 172 inïï½ Vp 0 kipïï½ As 12.48 in 2ïï½ V's min Vu Ïv Vsï¬ï ï¦ï§ ï¨ ï¶ï· ï¸ ïºï½ AASHTO LRFDï 5.8.3.5ï V's 514.889 kipïï½ F M'u Ïm dvï ï¦ï§ ï¨ ï¶ï· ï¸ 0.5 Nuï Ïn ï« cotÎ VuÏv Vpï 0.5 V'sïï ï¦ï§ ï¨ ï¶ï· ï¸ 2 0.45 Tuï phï 2 Ïvï Aoï ï¦ï§ ï¨ ï¶ï· ï¸ 2 ï«ïï«ïºï½ F 946.64 kipïï½ Fcheck if Aps fpsï As fyïï« Fï³ "OK"ï¬ï "N.G."ï¬ï ï¨ ï©ïºï½ AASHTO LRFDï EQ 5.8.3.6.3 1ï( )ï Fcheck "N.G."ï½ N.B.-The longitudinal reinforcement check can be ignored for typical multi-column pier cap. This check must be considered for straddle pier cap with no overhangs. Refer to AASHTO LRFD 5.8.3.5 for further information.
263 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT 4. COLUMN/DRILLED SHAFT LOADING AND DESIGN Superstructure to substructure force: AASHTO LRFDï SECTIONï 3ï LOADSï andï LOADï COMBINATIONSï Subscript: X = Parallel to the Bent cap Length and Z = Perpendicular to the bent Cap Length th 2.5 inïïºï½ (Haunch Thickness) Beam Depth, BmH FBmDïºï½ ColH HCol 0 ftïï«ïºï½ (Column height + 0 ft Column Capital) TribuLength FSpan BSpanï« 2 ïºï½ Scour Depth: hscour 0 ftïïºï½ Scour to Fixity Depth: hscf min 3 DsDiaï 10 ftïï¬ï ( )ïºï½ Total Drilled Shaft height: DsH hscour hscfï«ïºï½ DsH 10 ftïï½ ho BrgTh BmHï« thï« SlabThï«ïºï½ (Top of cap to top of slab height) ho 3.725 ftïï½ h6 ho 6ftï«ïºï½ (Top of cap to top of slab height + 6 ft) h6 9.725 ftïï½
264 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT hsup BmH thï« SlabThï« RailHï«ïºï½ (Height of Superstructure) hsup 6.267 ftïï½ h1 DsH ColHï« hCap 2 ï«ïºï½ (Height of Cap cg from Fixity of Dshaft) h1 34 ftïï½ h2 DsH ColHï« hCapï« h6ï«ïºï½ h2 45.725 ftïï½ h3 DsH ColHï« hCapï« BrgThï« hsup 2 ï«ïºï½ h3 39.425 ftïï½ Tributary area for Superstructure, Asuper hsup( ) TribuLength( )ïïºï½ Asuper 438.667 ft 2ïï½ LIVE LOAD REACTIONS: LL Live load Reaction LL on cap can be taken only the vertical Rxn occurs when HL93 is on both the forward and backward span or when HL93 Loading is on one span only which causes torsion too. To maximize the torsion, LL only acts on the longer span between forward and backward span. For maximum reaction, place rear axle (P3 = 32 kip) over the support at bent while the design truck traveling along the span. Maximum Forward Span Design Truck (FTruck) & Lane Load Reaction (FLane): FTruck P3 P2 FSpan 14 ftïï( ) FSpan ï©ïªï« ï¹ïºï»ïï« P1 FSpan 28ftï( ) FSpan ïï«ïºï½ FTruck 62.4 kipïï½ FLane wlane FSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ FLane 22.4 kip lane ïï½ Forward Span Live Load Reactions with Impact (FLLRxn): FLLRxn FLane FTruck 1 IMï«( )ïï«ïºï½ FLLRxn 105.392 kip lane ïï½ Maximum Backward Span Design Truck (BTruck) & Lane Load Reaction (BLane): BTruck P3 P2 BSpan 14 ftïï( ) BSpan ï©ïªï« ï¹ïºï»ïï« P1 BSpan 28ftï( ) BSpan ïï«ïºï½ BTruck 62.4 kipïï½ BLane wlane BSpan 2 ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ BLane 22.4 kip lane ïï½ Backward Span Live Load Reactions with Impact (BLLRxn): BLLRxn BLane BTruck 1 IMï«( )ïï«ïºï½ BLLRxn 105.392 kip lane ïï½ Live Load Reactions per Beam with Impact (BmLLRxn) using Distribution Factors: BmLLRxn LLRxn( ) max DFSFmax DFSBmaxï¬ï ï¨ ï©ïïºï½ Max reactionï whenï midï axleï onï supportï( ) BmLLRxn 72.556 kipbeamïï½ FBmLLRxn FLLRxn( ) DFSFmaxïïºï½ Only Forwardï Spanï isï Loadedï( ) FBmLLRxn 58.858 kip beam ïï½ BBmLLRxn BLLRxn( ) DFSBmaxïïºï½ Only Backwardï Spanï isï Loadedï( ) BBmLLRxn 58.858 kip beam ïï½ Torsion due to the eccentricity from CL of Bearing to CL of Bent when only Longer Span is loaded with HL-93 Loading
265 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT TorsionLL max FBmLLRxn BBmLLRxnï¬ï ( ) ebrgïïºï½ TorsionLL 63.763 kip ftï beam ïï½ Live Load Reactions per Beam without Impact (BmLLRxnn) using Distribution Factors: BmLLRxnn Lane Truckï«( ) max DFSFmax DFSBmaxï¬ï ï¨ ï©ïïºï½ BmLLRxnn 60.761 kipbeamïï½ FBmLLRxnn FLane FTruckï«( ) DFSFmaxï¨ ï©ïïºï½ FBmLLRxnn 47.358 kipbeamïï½ BBmLLRxnn BLane BTruckï«( ) DFSBmaxï¨ ï©ïïºï½ BBmLLRxnn 47.358 kipbeamïï½ Torsion due to the eccentricity of CL of Bearing and CL of Bent without Impact TorsionLLn max FBmLLRxnn BBmLLRxnnï¬ï ï¨ ï© ebrgïïºï½ TorsionLLn 51.305 kftbeamïï½ CENTRIFUGAL FORCE: CF (AASHTO LRFD 3.6.3) Skew Angle of Bridge, θ 0 degïïºï½ Design Speed v 45 mphïïºï½ f g( ) 4 3 32.2 ft sec2 ïï¦ï§ï¨ ï¶ï·ï¸ ïºï½Degree of Curve, Ïc 0.00001 degïïºï½ (Input 4o curve or 0.00001o for 0o curve) Radius of Curvature, Rc 360 degï( ) 100ï ftï 2 Ïï Ïcï ïºï½ Rc 572957795.131 ftïï½ Rc â=ï¨ ï© Centri. Force Factor, C f v2 Rc gï ïïºï½ AASHTO LRFDï EQï 3.6.3ï 1ï( ) C 0ï½ Pcf C TruckTï NofLane( )ï m( )ïïºï½ Pcf 0 kipïï½ Centrifugal force parallel to bent (X-direction) CFX Pcf cos θ( )ï NofBm ï¦ï§ï¨ ï¶ï·ï¸ïºï½ CFX 0 kip beam ïï½ Centrifugal force normal to bent (Z-direction) CFZ Pcf sin θ( )ï NofBm ï¦ï§ï¨ ï¶ï·ï¸ïºï½ CFZ 0 kip beam ïï½ Moments at cg of the Bent Cap due to Centrifugal Force MCF_X CFZ h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MCF_X 0 kft beam ïï½ MCF_Z CFX h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MCF_Z 0 kft beam ïï½ BRAKING FORCE: BR (AASHTO LRFD 3.6.4) The braking force shall be taken as maximum of 5% of the Resultant Truck plus lane load OR 5% of the Design Tandem plus Lane Load or 25% of the design truck. Pbr1 5% Lane TruckTï«( )ï NofLane( )ï m( )ïïºï½ Truck Laneï«( ) Pbr1 14.892 kipïï½
266 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Pbr2 5% Lane 50 kipïï«( )ï NofLane( )ï m( )ïïºï½ Tandem Laneï«( ) Pbr2 12.087 kipïï½ Pbr3 25% TruckT( )ï NofLane( )ï m( )ïïºï½ DesignTruck( ) Pbr3 45.9 kipïï½ Pbr max Pbr1 Pbr2ï¬ï Pbr3ï¬ï ï¨ ï©ïºï½ Pbr 45.9 kipïï½ Braking force parallel to bent (X-direction) BRX Pbr sin θ( )ï NofBm ïºï½ BRX 0 kip beam ïï½ Braking force normal to bent (Z-direction) BRZ Pbr cos θ( )ï NofBm ïºï½ BRZ 3.825 kip beam ïï½ Moments at cg of the Bent Cap due to Braking Force MBR_X BRZ h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MBR_X 44.848 kft beam ïï½ MBR_Z BRX h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MBR_Z 0 kft beam ïï½ WATER LOADS: WA (AASHTO LRFD 3.7) Note : To be applied only on bridge components below design high water surface. Substructure: V 0 ft sec ïºï½ (Design Stream Velocity) Specific Weight, γwater 62.4 pcfïïºï½ Longitudinal Stream Pressure: AASHTO LRFD 3.7.3.1 AASHTO LRFD Table 3.7.3.1-1 for Drag Coefficient, CD semicircular-nosed pier 0.7 square-ended pier 1.4 debries lodged against the pier 1.4 wedged-nosed pier with nose angle 90 deg or less 0.8 Columns and Drilled Shafts: Longitudinal Drag Force Coefficient for Column, CD_col 1.4ïºï½ Longitudinal Drag Force Coefficient for Drilled Shaft, CD_ds 0.7ïºï½ pT CD V2 2 gïï γwaterï= (Longitudinal stream pressure) AASHTO LRFD EQ (C3.7.3.1-1) pT_col CD_col V2 2 gïï γwaterïïºï½ pT_col 0 ksfïï½
267 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT pT_ds CD_ds V2 2 gïï γwaterïïºï½ pT_ds 0 ksfïï½ Lateral Stream Pressure: AASHTO LRFD 3.7.3.2 AASHTO LRFD Table 3.7.3.2-1 for Lateral Drag Coefficient, CL Angle,ï±, between direction of flowr and longitudina axis of the pie 0deg 0 5deg 0.5 10deg 0.7 20deg 0.9 >30deg 1 CL Lateral Drag Force Coefficient, CL 0.0ïºï½ Lateral stream pressure, pL CL V2 2 gïï γwaterïïºï½ pL 0 ksfïï½ Bent Cap: Longitudinal stream pressure CL 1.4ïºï½ pTcap CL V2 2 gïï γwaterïïºï½ pTcap 0 ksfïï½ WA on Columns Water force on column parallel to bent (X-direction) WAcol_X wCol pT_colïïºï½ WAcol_X 0 kip ft ïï½ If angle between direction of flow and longitudinal axis of pile = 0 then apply load at one exterior column only otherwise apply it on all columns. WA at all columns will be distributed uniformly rather than triangular distribution on column height. Water force on column normal to bent (Z-direction) WAcol_Z bCol pLïïºï½ WAcol_Z 0 kip ft ïï½ WA on Drilled Shafts Water force on drilled shaft parallel to bent (X-direction) WAdshaft_X DsDia pT_dsïïºï½ WAdshaft_X 0 kip ft ïï½ Water force on drilled shaft normal to bent (Z-direction) WAdshaft_Z DsDia pLïïºï½ WAdshaft_Z 0 kip ft ïï½ WA on Bent Cap (input as a punctual load) Water force on bent cap parallel to bent (X-direction) WAcap_X wCap hCapï pTcapï¨ ï©ïïºï½ (If design HW is below cap then input zero) WAcap_X 0 kipïï½ Water force on bent cap normal to bent (Z-direction)
268 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT WAcap_Z hCap pLïïºï½ (If design HW is below cap then input zero) WAcap_Z 0 kip ft ïï½ WIND ON SUPERSTRUCTURE: WS (AASHTO LRFD 3.8.1.2.2) Note : Wind Loads to be applied only on bridge exposed components above water surface AASHTO LRFD Table 3.8.1.2.2-1 specifies the wind load components for various angles of attack. In order to simplify the analysis, this calculation considers as default values those for girders which generate the maximum effect on structure. The results can be considered as conservative. For a superstructure other than a girder type and/or for a more detailed analysis, use the proper values as specified in the above mentioned table. AASHTO LRFD table 3.8.1.2.2-1 (modified) If the bridge is approximately 30â high and local wind velocities are known to be less than 100 mph, wind load for this bridge should be from AASHTO LRFD TABLE 3.8.2.2-1. Otherwise use AASHTO LRFD EQ 3.8.1.2.1-1 as mentioned above. ptsup 0.05ksfïºï½ Normal to superstructure (conservative suggested value 0.050 ksf) plsup 0.012ksfïºï½ Along Superstructure (conservative suggested value 0.019 ksf) WSchk if ptsup hsupï 0.3 klfïï³ "OK"ï¬ï "N.G."ï¬ï ï¨ ï©ïºï½ WSchk "OK"ï½ WsupLong plsup hsupï TribuLengthï NofBm ïºï½ WsupLong 0.439 kip beam ïï½ WsupTrans ptsup hsupï TribuLengthï NofBm ïºï½ WsupTrans 1.828 kip beam ïï½ Wind force on superstructure parallel to bent (X-direction) WSsuper_X WsupLong sin θ( )ï WsupTrans cos θ( )ïï«ïºï½ WSsuper_X 1.828 kipbeamïï½ Wind force on superstructure normal to bent (Z-direction) WSsuper_Z WsupLong cos θ( )ï WsupTrans sin θ( )ïï«ïºï½ WSsuper_Z 0.439 kipbeamïï½ Moments at cg of the Bent Cap due to Wind load on superstructure Msuper_X WSsuper_Z hCap 2 BrgThï« hsup 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Msuper_X 2.38 kft beam ïï½
269 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Msuper_Z WSsuper_X hCap 2 BrgThï« hsup 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ Msuper_Z 9.916 kft beam ïï½ WIND ON SUBSTRUCTURE: WS (AASHTO LRFD 3.8.1.2.3) Base Wind pressure, psub 0.04 ksfïïºï½ will be applied on exposed substructure both transverse & longitudinal direction Wind on Columns Wind force on columns parallel to bent (X-direction) WScol_X psub bCol cos θ( )ï wCol sin θ( )ïï«( )ïï©ï« ï¹ï»ïºï½ WScol_X 0.14 kip ft ïï½ Apply WS loads at all columns even with zero degree attack angle. Wind force on columns normal to bent (Z-direction) WScol_Z psub bCol sin θ( )ï wCol cos θ( )ïï«( )ïï©ï« ï¹ï»ïºï½ WScol_Z 0.14 kip ft ïï½ Wind on Bent Cap & Ear Wall WSew_X psub hEarWallï wEarWall sin θ( )ï wCap cos θ( )ïï«( )ïïºï½ WSew_X 0 kipïï½ WSew_Z psub hEarWallï wEarWall cos θ( )ï wCap sin θ( )ïï«( )ïïºï½ WSew_Z 0 kipïï½ Wind force on bent cap parallel to bent (X-direction) WScap_X psub hCapï CapL sin θ( )ï wCap cos θ( )ïï«( )ïï©ï« ï¹ï» WSew_Xï«ïºï½ (punctual load) WScap_X 0.64 kipïï½ Wind force on bent cap normal to bent (Z-direction) WScap_Z psub hCapï CapL cos θ( )ï wCap sin θ( )ïï«( )ïï©ï« ï¹ï» WSew_Zï« CapL ïºï½ WScap_Z 0.16 kip ft ïï½ WIND ON VEHICLES: WL (AASHTO LRFD 3.8.1.3) AASHTO LRFD Table 3.8.1.3-1 specifies the wind on live load components for various angles of attack. In order to simplify the analysis, this calculation considers as default values the maximum wind components as defined in the above mentioned table. The results can be considered conservative. For a more detailed analysis, use the proper skew angle according to the table. AASHTO LRFD table 3.8.1.3-1 (suggested value 0.1 kip/ft) pWLt 0.1 kip ft ïºï½ (suggested value 0.038 kip/ft) pWLl 0.04 kip ft ïºï½
270 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT WLPar pWLl TribuLengthï NofBm ïºï½ WLPar 0.233 kip beam ïï½ WLNor pWLt TribuLengthï NofBm ïºï½ WLNor 0.583 kip beam ïï½ Wind force on live load parallel to bent (X-direction) WLX WLNor cos θ( )ï WLPar sin θ( )ïï«ïºï½ WLX 0.583 kipbeamïï½ Wind force on live load normal to bent (Z-direction) WLZ WLNor sin θ( )ï WLPar cos θ( )ïï«ïºï½ WLZ 0.233 kipbeamïï½ Moments at cg of the Bent Cap due to Wind load on Live Load MWL_X WLZ h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MWL_X 2.736 kft beam ïï½ MWL_Z WLX h6 hCap 2 ï«ï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MWL_Z 6.84 kft beam ïï½ Vertical Wind Pressure: (AASHTO LRFD 3.8.2) DeckWidth FDeckWïºï½ Bridge deck width including parapet and sidewalk Puplift 0.02ksf( )ï DeckWidthï TribuLengthïïºï½ (Acts upword Y-direction) Puplift 66.033ï kipïï½ Applied at the windward quarter-point of the deck width. Note: Applied only for Strength III and for Service IV limit states only when the direction of wind is perpendicular to the longitudinal axis of the bridge. (AASHTO LRFD table 3.4,1-2, factors for permanent loads) Load Combinations: using AASHTO LRFD Table 3.4.1-1 STRENGTH_I 1.25 DCï 1.5 DWïï« 1.75 LL BRï« CFï«( )ïï« 1.0 WAïï«= STRENGTH_IA 0.9 DCï 0.65 DWïï« 1.75 LL BRï« CFï«( )ïï« 1.0 WAïï«= STRENGTH_III 1.25 DCï 1.5 DWïï« 1.4 WSïï« 1.0 WAïï« 1.4 Pupliftïï«= STRENGTH_IIIA 0.9 DCï 0.65 DWïï« 1.4 WSïï« 1.0 WAïï« 1.4 Pupliftïï«= STRENGTH_V 1.25 DCï 1.5 DWïï« 1.35 LL BRï« CFï«( )ïï« 0.4 WSïï« 1.0 WAïï« 1.0 WLïï«= STRENGTH_VA 0.9 DCï 0.65 DWïï« 1.35 LL BRï« CFï«( )ïï« 0.4 WSïï« 1.0 WAïï« 1.0 WLïï«= SERVICE_I 1.0 DCï 1.0 DWïï« 1.0 LLno_Impact BRï« CFï«ï¨ ï©ïï« 0.3 WSïï« 1.0 WAïï« 1.0 WLïï«=
271 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT All these loadings as computed above such as DC, DW, LL, WL, WA, WS etc. are placed on the bent frame composed of bent cap and columns and drilled shafts. The frame is analyzed in RISA using load combinations as stated above. Output Loadings for various load combinations for column and drilled shaft are used to run PCA Column program to design the columns. It is found that 3'-6"X3'-6" Column with 12~#11 bars is sufficient for the loadings. Drilled shaft and other foundation shall be designed for appropriate loads. Total Vertical Foundation Load at Service I Limit State: Forward Span Superstructure DC (FFDC) & DW (FFDW): FFDC FNofBm 2ï( ) FSuperDCIntï 2 FSuperDCExtïï«ïºï½ FFDC 259.607 kipïï½ FFDW FNofBm( ) FSuperDWïïºï½ FFDW 38.5 kipïï½ Backward Span Superstructure DC (FBDC) & DW (FBDW): FBDC BNofBm 2ï( ) BSuperDCIntï 2 BSuperDCExtïï«ïºï½ FBDC 259.607 kipïï½ FBDW BNofBm( ) BSuperDWïïºï½ FBDW 38.5 kipïï½ Total Cap Dead Load Weight (TCapDC): TCapDC CapDC( ) CapL( )ï NofBm( ) BrgSeatDC( )ïï« EarWallDCï«ïºï½ TCapDC 112.8 kipïï½ Total DL on columns including Cap weight (FDC): FDL FFDC FFDWï«ï¨ ï© FBDC FBDWï«ï¨ ï©ï« TCapDCï«ïºï½ FDL 709.015 kipïï½ Column & Drilled Shaft Self Weight: DSahft Length, DsHt 0 ftïïºï½ if Rounded Col, ColDia 0 ftïïºï½ ColDC if ColDia 0ftï¾ Ï 4 ColDia( )2ï HCol( )ï γcïï¬ï wCol bColï HColï γcïï¬ï ï©ïªï« ï¹ïºï»ïºï½ Column Wt, ColDC 40.425 kipïï½ DsDC Ï 4 DsDia( )2ï DsHt( )ï γcïïºï½ Dr Shaft Wt, DsDC 0 kipïï½ Total Dead Load on Drilled Shaft (DL_on_DShaft): DL_on_DShaft FDL NofCol( ) ColDC( )ïï« NofDs( ) DsDC( )ïï«ïºï½ DL_on_DShaft 789.865 kipïï½ Live Load on Drilled Shaft: m 0.85ï½ (Multile Presence Factors for 3 Lanes) AASHTO LRFDï Tableï 3.6.1.1.2ï 1ï( ) RLL Lane Truckï«( ) NofLane( )ï m( )ïïºï½ (Total LLRxn without Impact) RLL 277.44 kipïï½ Total Load, DL+LL per Drilled Shaft of Intermediate Bent:
272 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT Load_on_DShaft DL_on_DShaft RLLï« NofDs ïºï½ Load_on_DShaft 266.8 tonïï½ 5. PRECAST COMPONENT DESIGN Precast Cap Construction and Handling: w b hï γcïïºï½ (Cap selfweight) w 2.4 klfïï½ Due to the location of girder bolts on cap, pickup points at 8' from both ends. Indeed, we can model cap lifting points as simply supported beam under self weight supported at 8' and 39' respectively from very end.  w = 2.4 klf lc = 8 ft lb = 31 ftla = 8 ft la 8 ftïïºï½ lb 31 ftïïºï½ lc 8ftïºï½ Construction factor: λcons 1.25ïºï½ λcons 1.25ï½ Maximum Positive Moment (MmaxP) & Negative Moment (MmaxN): MmaxP w CapLï 2 CapL 4 laïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MmaxP 211.5 kftïï½ MmaxN w la 2ï 2 ïºï½ MmaxN 76.8 kftïï½ Factored Maximum Positive Moment (MuP) & Negative Moment (MuN):
273 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT MuP λcons MmaxPïïºï½ MuP 264.375 kftïï½ MuN λcons MmaxNïïºï½ MuN 96 kftïï½ S b h2ï 6 ïºï½ (Cap Section Modulus) S 18432 in3ïï½ Maximum Positive Stress (ftP) & Negative Stress (ftN): ftP MuP S ïºï½ ftP 172.119 psiïï½ ftN MuN S ïºï½ ftN 62.5 psiïï½ Modulus of Rupture: According PCI hand book 6th edition modulus of rupture, fr = 7.5\/f'c is divided by a safety factor 1.5 in order to design a member without cracking f'c 5 ksiïïºï½ (Compressive Strength of Concrete) Unit weight factor, λ 1ïºï½ fr 5 λï f'c psiïïïºï½ (PCI EQ 5.3.3.2) fr 353.553 psiïï½ fr_check if fr ftPï¾ï¨ ï© fr ftNï¾ï¨ ï©ï "OK"ï¬ï "N.G."ï¬ï ï©ï« ï¹ï»ïºï½ fr_check "OK"ï½ Precast Column Construction and Handling: wCol 3.5 ftïï½ (Column width) Column breadth, bCol 3.5 ftïï½ wcol wCol bColï γcïïºï½ (Column self weight) wcol 1.837 klfïï½ Due to the location of girder bolts on column, pickup points at 3' from both ends. Indeed, we can model column lifting points as simply supported beam under self weight supported at 3' and 19' respectively from very end.  w  = 1.837 klf lc = 3 ftlb = 16 ft la = 3 ft la 3 ftïïºï½ lb 16 ftïïºï½ lc 3 ftïïºï½ Maximum Positive Moment (MmaxP) & Negative Moment (MmaxN):
274 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT MmaxP wcol HColï 2 HCol 4 laïï¦ï§ï¨ ï¶ï·ï¸ïïºï½ MmaxP 50.531 kftïï½ MmaxN wcol la 2ï 2 ïºï½ MmaxN 8.269 kftïï½ Factored Maximum Positive Moment (MuP) & Negative Moment (MuN): MuP λcons MmaxPïïºï½ MuP 63.164 kftïï½ MuN λcons MmaxNïïºï½ MuN 10.336 kftïï½ Scol wCol bCol2ï 6 ïºï½ (Column Section Modulus) Scol 12348 in 3ïï½ Maximum Positive Stress (ftP) & Negative Stress (ftN): ftP MuP Scol ïºï½ ftP 61.384 psiïï½ ftN MuN Scol ïºï½ ftN 10.045 psiïï½ Modulus of Rupture: According PCI hand book 6th edition modulus of rupture, fr = 7.5\/f'c is divided by a safety factor 1.5 in order to design a member without cracking f'c 5 ksiïïºï½ (Compressive Strength of Concrete) Unit weight factor, λ 1ïºï½ fr 5 λï f'c psiïïïºï½ (PCI EQ 5.3.3.2) fr 353.553 psiïï½ fr_check if fr ftPï¾ï¨ ï© fr ftNï¾ï¨ ï©ï "OK"ï¬ï "N.G."ï¬ï ï©ï« ï¹ï»ïºï½ fr_check "OK"ï½ DEVELOPMENT LENGTH: AASHTO LRFD 5.11 Ab 1.56 in 2ïïºï½ (Area of Bar) db 1.41 inïïºï½ (Diameter of Bar) f'c 5 ksiïïºï½ Modification Factor: According to AASHTO LRFD 5.11.2.1.2, the basic development length, ldb is required to multiply by the modification factor to obtain the development length ld for tension or compression. λmod 1.0ïºï½ Basic Tension Development: AASHTO LRFD 5.11.2.1 for bars upto #11
275 INNOVATIVE BRIDGE DESIGNS FOR RAPID RENEWAL: ABC TOOLKIT ldb max 1.25 Ab in ï¦ï§ï¨ ï¶ï·ï¸ï fy f'c ksiï ï 0.4 dbï fy ksi ïï¬ï 12 inïï¬ï ï©ïªïªï« ï¹ïº ïºï» ïºï½ (AASHTO LRFD 5.11.2.1.1) ldb 52.324 inïï½ ld λmodï¨ ï© ldbïïºï½ ld 4.36 ftïï½ Basic Compression Development: AASHTO LRFD 5.11.2.2 ldb max 0.63 dbï fyï f'c ksiï 0.3 dbï fy ksi ïï¬ï 8 inïï¬ï ï¦ï§ï§ï¨ ï¶ï· ï·ï¸ ïºï½ AASHTO LRFDï EQï 5.11.2.2.1 1ï 2ï¬ï ( )ï ldb 25.38 inïï½ ld λmodï¨ ï© ldbïïºï½ ld 2.115 ftïï½