Design Guide for Bridges for Service Life (2013) / Chapter Skim
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543 AppENDix A Design Provisions for Self-Stressing System for Bridge Application with Emphasis on Precast Panel Deck System 544 A.1 Construction Procedure Overview 545 A.2 Design Considerations 546 A.3 Design Procedure and Implementation Details 556 A.4 Design Flowchart 557 A.5 Design Aids for Two-Span Bridges 559 AppENDix B Displacement of Skewed Bridge 559 B.1 Background 563 B.2 Analyses for Transverse Response to Thermal Expansion 566 B.3 Expected Transverse Movement with Typical Integral Abutment 570 AppENDix C Design of Piles for Fatigue and Stability 570 C.1 Estimation of Maximum Allowable Strain 573 C.2 Pushover Analysis Example 576 AppENDix D Restraint Moments 576 D.1 Background 581 D.2 Design Recommendations 587 AppENDix E Design Steps for Seamless Bridge System Developed by SHRP 2 Project R19A 590 E.1 Structural Analysis 590 E.2 Design of System Components 593 E.3 Cracked Section Analysis 596 AppENDix F Curved Girder Bridges 596 F.1 Background 597 F.2 Calculating Magnitude and Direction of End Displacement 600 F.3 Optimum Pile Orientation
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602 AppENDix G Design Provision for Sliding Surfaces Used in Bearing Devices for Service Life 602 G.1 Introduction 603 G.2 Elements of Design Provisions 609 G.3 Design Process for Sliding Surfaces
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11 DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK The design for service life is gaining more importance as limited resources demand enhancing the service life of existing and new bridges. As part of SHRP 2 Project R19A, Bridges for Service Life Beyond 100 Years: Innovative Systems, Subsystems, and Components, a systematic and general approach to design for service life has been developed.
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2DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE this line of thinking. It is important to note that in the early 1970s, bridge engineers developed criteria for steel bridge details to protect against fatigue and fracture failure.
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3Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK should be repaired while kept open to traffic.
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4DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE the bridge in 1974. By the early 1990s, traffic on the bridge had dwindled to about 4,000 cars a day, and in 1991, the Eads Bridge was closed.
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5Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK strategies for enhancing the service life of different bridge elements, components, and subsystems must be given critical consideration.
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6DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 1.3 bridge Service LiFe terminoLogy And reLAtionShiPS The following sections define service life–related terms and describe the relationships used in the Guide. 1.3.1 Service Life and Design Life Service life.
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7Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK • The end of service life for a bridge element, component, or subsystem does not necessarily signify the end of bridge system service life as long as the bridge element, component, or subsystem could be replaced or resume its function with a retrofit.
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8DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE particular service life issue is highly dependent on many factors that vary from location to location and state to state. A solution also depends on local practices and preferences.
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9Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK The following sections provide an overview of the general approach used in the Guide.
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10 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 2. Identify feasible bridge system alternatives that satisfy design provisions of LRFD specifications.
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11 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK Guide, the designer may change the deck thickness to 9 in.
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12 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE bridge elements, components, and subsystems are carried out separately. Thus, there is a need to make sure that these changes are compatible and are not contradictory or overly conservative.
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13 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK Steps 9 through 12.
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14 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE basic information for materials used in bridge subsystems and elements specifically addressed in other chapters of the Guide. Chapter 4.
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15 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK 1.6.1 Description of Bridge Elements, Components, and Systems These sections of each chapter provide brief descriptions of, and essential information related to, both commonly used and more recently developed types of bridge components, elements, subsystems, and systems.
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16 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 1.6.3 mitigation Strategies When possible, each chapter provides provable solutions for major factors affecting the service life of a particular bridge element, component, subsystem, or system. Some chapters also include technology tables that summarize major characteristics associated with each solution and provide the potential solutions to factors affecting service life in a form that is easier to comprehend.
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17 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK provided in various chapters of the Guide summarize strategies that can be used to mitigate various basic factors capable of reducing service life.
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18 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE The sample table in Figure 1.9 lists the advantages and disadvantages for each possible solution capable of mitigating the adverse service life consequences of trafficinduced loads. In some cases, more information than just advantages and disadvantages is provided, such as qualitative assessment of maintenance cost.
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19 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK Enhanced service life for bridge elements, components, subsystems, and systems can be achieved through • Use of durable materials; • Use of passive or active protection systems; Identify DEMAND requirements.
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20 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE • Optimum selection of details; • Optimum maintenance and repair; • Reduced service level; • Increased factor of safety or reduction in stress levels; and • Isolation from risk damage. To estimate the service life of bridge elements, components, or subsystems quantitatively, the following information is needed: • Source of deterioration; • Deterioration mechanism; • Deterioration models; and • Failure modes.
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21 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK In practice, the development of realistic behavioral deterioration models is a dataintensive process complicated by lack of knowledge of the underlying physical and chemical processes fostering deterioration, as well as by data availability.
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22 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE In the case of chloride- and carbonation-induced corrosion, there is some level of agreement within the scientific community as to the existence of deterioration models. However, for other deterioration modes, such as sulfate attack, alkali-silica reactivity (ASR)
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23 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK Equation 1.4 should be used in conjunction with probabilistic approaches to account for the variability of several parameters, such as apparent coefficient of diffusion, chloride concentration, and critical chloride level to start corrosion.
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24 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Two general design approaches for service life are the finite service life approach and the target service life approach. When the design service life (ts)
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25 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK a specified or target service life.
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26 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE customarily provided to the bridge owner, except that the Owner's Manual contains much more detailed information. 1.9 indePendent review oF deSign For Service LiFe ProceSS The design for service life processes, results, and recommendations as summarized in the bridge Owner's Manual should be checked by an independent and knowledgeable third party.
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27 Chapter 1.
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28 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Figure 1.14. Aerial conception of bridge project.
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29 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK • Spans over a navigable waterway with primarily brackish conditions, and located adjacent to a park with water access for jet skis; • Located near the coastline with possible salt water storm surge and potential hurricane force winds with gusts up to 150 mph; and • Located in an area where local aggregates are subject to ASR.
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30 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 1b. Identify local factors affecting service life.
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31 Chapter 1.
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32 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Local Site Category (continued) Local Site Criteria to Be Specified (continued)
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33 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK current example, it is assumed that only the cast-in-place option is selected, as indicated in the typical girder cross section shown in Figure 1.16.
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34 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Figure 1.19. Screenshot of navigation through fault tree using an Excel worksheet.
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35 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK loads or system-dependent loads can reduce bridge-deck service life.
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36 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 1.11.3 Developing Strategies and Alternative Solutions Once the fault tree is completed and all applicable factors are identified, the individual strategies capable of mitigating the factors can be collected. If software is used to work through the fault tree, then this step can be automated based on the selections made.
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37 Chapter 1.
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38 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Se rv ic e Li fe Is su e C o rr es p o n d in g P ro je ct R eq u ir em en ts Se ct io n M it ig at in g S tr at eg y A d va n ta g e D is ad va n ta g e Sy st em fr am in g re st ra in t D ec k sh rin ka ge r es tr ai nt fr om s he ar s tu ds 4.
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39 Chapter 1.
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40 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE tABLE 1.3. LiSt oF StrAtegieS SPeciFic For deveLoPing deck ALternAtiveS Issue Strategy Overload Increase deck thinness Fatigue Design per AASHTO Wear Concrete mix Membrane and overlay Increase thickness System restraint Accurate modeling during structural analysis of bridge system Differential shrinkage Concrete mix: Use mix with low modulus Deicing Impermeable concrete Stainless steel Specify nonchloride-based deicing Membrane and overlay Freeze–thaw Concrete mix: Air content Salt spray Stainless steel Stay-in-place metal deck to protect bottom Deck bottom sealer and top membrane Humidity Use aggregate that is not sensitive to humidity ASR/ACR Concrete mix nonreactive aggregate For each alternative shown in Table 1.4, Rows 2 through 11 show the service life design factors identified in Table 1.3 and corresponding strategies selected for each alternative.
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41 Chapter 1.
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42 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE 1.11.4 Evaluating Alternatives The next step is predicting the service life of each alternative (Step 5 in Figure 1.17) and comparing it with the design service life of the bridge system as specified by the owner and project requirements.
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43 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK Life-365 assumes that repair action is at set time intervals, say, every 10 or 20 years, and set cost per unit area in square feet.
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44 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE every 10 years, during which 20% of the surface area is repaired. These assumptions are used for the sake of demonstration and will vary based on various DOT preferences and practices.
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45 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK tABLE 1.6 PArAmeterS SPeciFic to eAch ALternAtive From tAbLe 1.4 Analysis Parameter AASHTO Design Alternative 1 Alternative 2 Alternative 3 Alternative 4 Concrete mix type Regular Silica fume Regular Regular Regular Water-cement ratio 0.42 0.35 0.42 0.42 0.42 Slag (%)
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46 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Alternative 1. This alternative uses impermeable concrete by incorporating 5% silica fume into the mix.
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47 Chapter 1. DESiGN FOR SERviCE LiFE: GENERAL FRAMEWORK Alternative 4.
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48 DESiGN GUiDE FOR BRiDGES FOR SERviCE LiFE Design for service life is a context-sensitive problem: local agency practices and preferences are important. Customizing the Guide can be achieved by using the general framework outlined in these pages and incorporating strategies and solutions preferred by each DOT for factors affecting the service life of its bridges.
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