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From page 9... ... 9 This chapter focuses on the laboratory tests conducted as part of Task 16 in Phase V The chapter provides a brief review of typical WT cross-frame details in the United States, an overview of the design and detailing of the test specimens, a summary of the experimental testing protocols, stiffness response results from the laboratory tests, and FEA model validation. Read the entire page →
From page 10... ... Figure 3-1. Sample flange-connected WT section. Read the entire page →
From page 11... ... Figure 3-2. Sample stem-connected WT section with coping detail. Read the entire page →
From page 12... ... Figure 3-3. Sample stem-connected WT section with overhang detail. Read the entire page →
From page 13... ... Experimental Program 13 stem-connected (coped) detail for an X-type cross-frame, and Figure 3-3 illustrates a stemconnected (overhang) Read the entire page →
From page 14... ... 14 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections as "constants" were established based on several different limiting factors. For instance, many of the parameters related to connection strength (e.g., number of bolts, size of bolts, weld length, overlap dimension of plates) Read the entire page →
From page 15... ... Experimental Program 15 Grouping Constant Value Basis Connection Plate Width 11 inches Limited by the MTS grips Length 13 inches (bolted specimens) ; 11.5 inches (welded) Read the entire page →
From page 16... ... 16 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections Specimen ID Connection Plate-Gusset Plate ConnectionGusset Plate-WT Connection Gusset Plate Thickness (inch) Inclusion of Gusset Plate WT Section Connected Portion; Orientation Number of Tests BB-1 Bolted-Bolted 0.5 Yes/Noa WT4×9 Flange; Bothb 3 BB-2 Bolted-Bolted 0.75 Yes/Noa WT5×15 Flange; Bothb 3 BW-1 Bolted-Welded 0.5 Yes/Noa WT4×9 Flange; Bothb 3 BW-2 Bolted-Welded 0.75 Yes/Noa WT5×15 Flange; Bothb 3 BW-3 Bolted-Welded 0.5 Yes/Noa WT4×9 Stem (coped) Read the entire page →
From page 17... ... Experimental Program 17 • e gusset plate thickness for each specimen was chosen based on the assumed WT section. To maximize out-of-plane eccentricity, a thicker gusset plate (0.75 inch) Read the entire page →
From page 18... ... 18 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections Specimen ID Test ID a Eccentricity (inch) Out-of-Plane In-Plane BB-1 A 1.71 -S 0.46 -NG 1.08 -BB-2 A 2.23 -S 0.73 -NG 1.48 -BW-1 A 1.71 -S 0.46 -NG 1.08 -BW-2 A 2.23 -S 0.73 -NG 1.48 -BW-3 A 1.04 -S 0.21 -NG 0.42 -BW-4 A 1.28 -S 0.23 -NG 0.53 -BW-5 A 1.04 4.94 S 0.21 4.94 NG 0.42 4.94 BW-6 A 1.28 5.00 S 0.23 5.00 NG 0.53 5.00 WW-1 -- 1.71 -WW-2 -- 2.23 -WW-3 -- 2.67 -WW-4 -- 0.46 -WW-5 -- 0.73 -WW-6 -- 1.17 -a "A" represents additive eccentricity; "S" represents subtractive eccentricity; "NG" represents specimens with the connection plates removed. Read the entire page →
From page 19... ... Experimental Program 19 Figure 3-5. Photographs of five sample test specimens. Read the entire page →
From page 20... ... 20 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections Preliminary Sketch Experimental Test Setup Figure 3-6. MTS load frame with installed specimen. Read the entire page →
From page 21... ... Experimental Program 21 of the instrumentation plan, as it pertains to the specific goals outlined above, is summarized herein and further illustrated in Figure 3-7: • To measure the axial load and displacement of the specimen, the load cell and displacement transducer integrated into the MTS load frame were utilized. • To measure the strain/stress response of the specimen, weldable strain gages were installed to the WT sections. Read the entire page →
From page 22... ... 22 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections in behavior. The experimental tests were displacement-controlled, meaning that a specified peak displacement was achieved in axial tension and compression. Read the entire page →
From page 23... ... Experimental Program 23 3.4 Experimental Results As previously mentioned, 14 WT specimens were fabricated and tested in a 220-kip MTS load frame at the Ferguson Structural Engineering Laboratory. Each specimen was loaded in axial tension and compression under a cyclic ramp load, where the following results were measured: (1) Read the entire page →
From page 24... ... 24 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections In addition to the localized eects, the torch-cutting and welding processes induced global imperfections in the WT members. As evidenced by the test specimens, the WT members shipped to the Ferguson Structural Engineering Laboratory typically had an upward camber on the order of 1/16th of an inch in many cases. Read the entire page →
From page 25... ... Experimental Program 25 Additional arrows are provided on the graphs to illustrate the precise location where the measurements were taken. From Figure 3-12, the following observations can be made: • In the plane of the stem, a 1⁄16-inch out-of-straightness was measured at the mid-point of the WT relative to the member ends. Read the entire page →
From page 26... ... 26 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections -60 -40 -20 0 20 40 60 -0.2 -0.1 0 0.1 0.2 -120 -80 -40 0 40 80 120 -0.2 -0.1 0 0.1 0.2 -0.45 -0.3 -0.15 0 0.15 0.3 0.45 -0.2 -0.1 0 0.1 0.2 A xi al L oa d (k ip s) Read the entire page →
From page 27... ... Experimental Program 27 From Figure 3-13, the following observations can be made regarding the measured data from specimen WW-1. These trends are representative of the entire data set, as is documented later in this report. Read the entire page →
From page 28... ... 28 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections cross-frame members in I-girder bridges remain in the elastic range under service loads. Thus, accurately representing the elastic stiffness in structural analysis software is extremely important for the design of cross-frames for girder stability as well as evaluating cross-frame stress ranges for fatigue evaluation. Read the entire page →
From page 29... ... Experimental Program 29 • Plot C compares the response of bolted and welded connections for otherwise similar specimens. The only discernible difference between specimens BB-1_A and BW-1_A is the connection between the gusset plates and the WT member. Read the entire page →
From page 30... ... 30 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections Specimen ID Test ID Equivalent Stiffness (kips/inch* inch × 103) Read the entire page →
From page 31... ... Experimental Program 31 • Stem-connected specimens (coped) generally provide a stiffer response than flange-connected specimens (e.g., comparing BW-3 with BW-1) Read the entire page →
From page 32... ... 32 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections Section 3.4, these modeling parameters were prioritized in terms of potential modifications to achieve improved agreement with the experimental measurements. The following bulleted items summarize the key modeling assumptions used in the development of the 3D FEA preliminary models: • The specimens, including the WT member, gusset plates, and connection plates, were modeled using shell elements. Read the entire page →
From page 33... ... Experimental Program 33 of 65 ksi at a strain of 0.2. The inclusion of strain-hardening effects also minimized convergence issues that can sometimes arise in models adopting elastic-perfectly-plastic material models. Read the entire page →
From page 34... ... 34 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections and modeling techniques outlined above. Figure 3-18 is provided as an example. Read the entire page →
From page 35... ... Experimental Program 35 • Compared to the measured strain gage data, the preliminary FEA model resulted in higher strain/stresses in the flange and stem for the same amount of axial deformation. • The preliminary FEA model slightly underestimated the mid-point lateral deflection of the WT member for the same magnitude of axial deformation. Read the entire page →
From page 36... ... 36 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections It is apparent from this example data set that the preliminary model overestimated the stiffness by more than 30% in tension and compression. After adjusting the three prioritized modeling variables, the analytical solution was within 5% of the measured experimental value. Read the entire page →
From page 37... ... Experimental Program 37 -120 -80 -40 0 40 80 120 -0.2 -0.1 0 0.1 0.2 -60 -40 -20 0 20 40 60 -0.2 -0.1 0 0.1 0.2 -0.45 -0.3 -0.15 0 0.15 0.3 0.45 -0.2 -0.1 0 0.1 0.2 A xi al L oa d (k ip s) Read the entire page →
From page 38... ... 38 Improved Cross-Frame Analysis and Design: Wide-Flange T-Shape Sections The other three key modeling parameters investigated above, especially cross head grip length and restraint, have no effect on the behavior of cross-frames in I-girder bridge systems. These parameters are exclusive to the MTS testing procedures performed at the Ferguson Structural Engineering Laboratory. Read the entire page →

From page 9...

... 9 This chapter focuses on the laboratory tests conducted as part of Task 16 in Phase V The chapter provides a brief review of typical WT cross-frame details in the United States, an overview of the design and detailing of the test specimens, a summary of the experimental testing protocols, stiffness response results from the laboratory tests, and FEA model validation.