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From page 247... ... 248 Chapter 9 Flange/Deck Connection: Selection of Most Promising Connection Detail through Two-Phase Experimental Investigation 9.0 Introduction to Two-Phase Experimental Investigation to Finalize Connection Concept Detail for Further Study The headed bar detail and deformed wire reinforcement (DWR) and stainless steel (SS) Read the entire page →
From page 248... ... 249 bars in the transverse direction. The resulting deck thickness for the transverse joint only (or the combined transverse and longitudinal joints) Read the entire page →
From page 249... ... 250 Table 9.1.1: Reinforcement required for the U-bar detail in an 8 in. deck Locations fy = 60 ksi eγ = .75 eγ = 1 Bars Size Spacing (in) Read the entire page →
From page 250... ... 251 Table 9.1.4: Reinforcement required for the headed bar detail in a 6-¼ in. deck - Locations fy = 60 ksi eγ = .75 eγ = 1 Bars Size Spacing (in) Read the entire page →
From page 251... ... 252 Table 9.1.5: Negative moment longitudinal reinforcement Longitudinal Reinforcement (MU- region) Read the entire page →
From page 252... ... 253 metallic coating for the deck reinforcement, and 7 of the 38 states indicated that they were beginning to use solid stainless steel. In order to minimize the joint width between the precast flanges or panels, it is desirable to avoid epoxy-coated reinforcement because that may require a longer lap length to develop the reinforcement. Read the entire page →
From page 253... ... 254 Figure 9.1.1: U-bar longitudinal joint specimen Figure 9.1.2: Headed bar longitudinal joint specimen #5 bars @ 6 in spacing #4 bars @ 12 in spacing 6.25 in 120.0 in 6.0 in 15.0 in 4.5 in 1" 6.0 in 6.25 in #4 bars @ 12 in spacing #5 bars @ 6 in spacing 4.5 in 15.0 in 120.0 in Read the entire page →
From page 254... ... 255 Figure 9.1.3: U-bar transverse joint specimen Figure 9.1.4: Headed bar transverse joint specimen 9.1.2. Experimental Setup and Instrumentation Experimental Set-up Simple static tests were performed for both the longitudinal connections and transverse connections. Read the entire page →
From page 255... ... 256 As stated previously, the specimens representing the longitudinal joint direction were tested in bending. A modified version of the four point bending tested was used for the flexural test set-up. Read the entire page →
From page 256... ... 257 As stated previously the specimens representing the transverse joint direction were tested in tension. The tension test set-up was slightly more complicated than the flexural test set-up. Read the entire page →
From page 257... ... 258 Figure 9.1.6: Tension test set-up (Transverse Joint) Instrumentation The specimens were instrumented to achieve an understanding of the U-bar and headed bar details in bending and tension in the longitudinal and transverse joint tests, respectively. Read the entire page →
From page 258... ... 259 Figure 9.1.7: U-bar joint detail strain gage configuration Figure 9.1.8: Headed bar joint detail strain gage configuration The strain gage notation used in Figures 9.1.7 and 9.1.8 indicates the U-bar or the headed bar set where the gage was located and the relative position of that gage. For example, strain gage 2-3 indicated that the gage was located on U-bar 2 or headed bar set 2 and that it was the third gage away from the bearing surface of that bar. Read the entire page →
From page 259... ... 260 Strain gages were also installed on the transverse lacer bars. A strain gage was installed 1 in. Read the entire page →
From page 260... ... 261 (a) Reinforcement in the forms (b) Read the entire page →
From page 261... ... 262 Comparing the constructability of the U-bar and the headed bar joint details, the U-bar detail seemed to be the easiest to construct for two reasons. The U-bar detail produces a joint that is less congested than the headed bar detail and therefore allows for easier placement of precast deck components. Read the entire page →
From page 262... ... 263 also not a problem for the material. After determining the best fabrication method for the bends, no deformed wire reinforcement was broken during fabrication. Read the entire page →
From page 263... ... 264 An extensometer with the required 2 in. gage length was used to determine the strain in the deformed wire reinforcement (DWR) Read the entire page →
From page 264... ... 265 Figure 9.1.11: Stress versus strain curves for Deformed Wire Reinforcement (DWR) and Stainless Steel (SS) Read the entire page →
From page 265... ... 266 Figure 9.1.12: Connection detail, conceptual drawing Figure 9.1.13: Photo of the top connection detail Read the entire page →
From page 266... ... 267 Figure 9.1.14: Weld test set-up The welds tested were made using the Metal Inert Gas, Tungsten Inert Gas and Shielded Metal Arc Welding (MIG, TIG and SMAW) welding methods on all rebar materials. Read the entire page →
From page 267... ... 268 Table 9.1.9: Weld test results, one pass welds Material Welding Method Capacity (kips) Failure Mode Stainless Steel, fy = 75 ksi MIG 15.5 Weld Broke Deformed wire Reinforcement, fy = 75 ksi MIG 13 Rebar Pulled Out of Weld Conventional Rebar, fy = 60 ksi MIG 13.7 Rebar Pulled Out of Weld Stainless Steel fy = 75 ksi TIG 11.8 Weld Broke Deformed wire Reinforcement fy = 75 ksi TIG 15 Weld Broke Conventional Rebar fy = 60 ksi TIG 15.8 Weld Broke Figure 9.1.15: One pass weld failure The second set of weld tests consisted of the same welding methods and materials, but the threaded rods and rebar were beveled, so larger weld areas and capacities could be produced. Read the entire page →
From page 268... ... 269 of 75 ksi. These results indicated that the welds could yield the reinforcing material, but to account for any unforeseen forces in the experiment, larger weld capacities were preferred. Read the entire page →
From page 269... ... 270 Table 9.1.11: Weld test results, beveled welds and 110 ksi welding stick Material Welding Method Capacity (kips) Failure Mode Stainless Steel, fy = 75 ksi SMAW 21.4 Weld Broke Deformed wire Reinforcement, fy = 75 ksi SMAW 33.5 Weld Broke Conventional Rebar, fy = 60 ksi SMAW 29.5 Weld Broke Table 9.1.11 shows that the 110 ksi welding sticks and the SMAW welding method produced very strong welds with the deformed wire reinforcement and the conventional rebar, but the strength of the weld decreased for the stainless steel reinforcement. Read the entire page →
From page 270... ... 271 reinforcement was kept the same when the Grade 75 reinforcement was used. Considering the specimens with the Grade 75 reinforcement could resist a higher moment, a reinforcement ratio was used to adjust the loading demands to reflect this difference. Read the entire page →
From page 271... ... 272 Figure 9.1.16: Moment versus deflection curves Read the entire page →
From page 272... ... 273 Figure 9.1.17: Moment-versus-curvature curves From Figures 9.1.16 and 9.1.17, the ductility of the specimens can be seen. Figure 9.1.16 shows that the Ubar specimens, SB-1 and WB-1, produced larger deflections than the headed bar detail contained in specimen HB-1. Read the entire page →
From page 273... ... 274 curvature curves were constructed for both the U-bar detail and the headed bar detail. Two separate moment-versus-curvature curves had to be determined because of the different concrete strengths, assumed rebar yield strengths and reinforcement configurations used in the specimens. Read the entire page →
From page 274... ... 275 Table 9.1.14: Calculated moments and curvature (six-bar side) Headed Bar Detail (fy=60ksi) Read the entire page →
From page 275... ... 276 Figure 9.1.20: Measured and theoretical moment-versus-curvature curves for the U-bar details Figure 9.1.21: Measured and theoretical moment-versus-curvature curves for headed bar details Read the entire page →
From page 276... ... 277 Figures 9.1.20 and 9.1.21 show that all specimens produced a larger capacity than the theoretical capacity. Also, the specimens were more ductile than predicted by the theoretical curvature calculations based on nominal properties; the detailed explanation for this difference is provided later in reference to Figure 9.2.22. Read the entire page →
From page 277... ... 278 (a) Specimen SB-1 (b) Read the entire page →
From page 278... ... 279 The numbers written next to the cracks shown in Figure 9.1.22 represent the total force, in kips, applied to the specimen when the cracks formed. All flexural specimen failures were ductile, producing yielding in the reinforcement and crushing of the concrete on the compression face of the specimens, under the joint zone. Read the entire page →
From page 279... ... 280 (a) Bottom of U-bar 2 (Specimen SB-1) Read the entire page →
From page 280... ... 281 (g) Lacer Bars 1 and 2 (Specimen SB-1) Read the entire page →
From page 281... ... 282 (e) Bottom of U-bar 4 (Specimen WB-1) Read the entire page →
From page 282... ... 283 (a) Bottom of U-bar 2 (Specimen HB-1) Read the entire page →
From page 283... ... 284 (g) Lacer Bars 1 and 2 (Specimen HB-1) Read the entire page →
From page 284... ... 285 less than the expected tensile capacity. The low capacity could have been due to the fact that the welds broke during testing at a load of approximately 65 kips. Read the entire page →
From page 285... ... 286 result shows that both joint details could effectively be used as a transverse joint in a negative moment region, which would mainly produce global tension in the deck. Tension Specimen Behavior (Transverse Joint Behavior) Read the entire page →
From page 286... ... 287 (a) Specimen ST-1 (b) Read the entire page →
From page 287... ... 288 systematically throughout the testing of HT-1 and ST-1, but only two crack widths were measured at two different loads for specimen WT-1. The average crack width of all cracks within the joint zone at 55 kips (estimated service load level for ST-1 and WT-1) Read the entire page →
From page 288... ... 289 (a) Bottom of U-bar 2 (b) Read the entire page →
From page 289... ... 290 (a) Bottom Bar of Headed Bar Set 2 (Specimen HT-1) Read the entire page →
From page 290... ... 291 (g) Transverse Lacer Bars 1 and 2 Figure 9.1.29: Total force versus rebar strain for HT-1 9.1.6. Read the entire page →
From page 291... ... 292 fabricated wire mesh. The stainless steel reinforcement had the highest cost of 5000 dollars a ton including fabrication. Read the entire page →
From page 292... ... 293 Table 9.2.1: Testing parameters Specimen ID Concrete Strength Bar Spacing Joint Overlap Length (ksi) Read the entire page →
From page 293... ... 294 Figure 9.2.3: WB-3 longitudinal joint specimen Figure 9.2.4: WB-4 longitudinal joint specimen Figure 9.2.5: WT-1 transverse joint specimen (Tested in Phase I) 6.25 in #4 bars @ 12 in spacing #5 bars @ 6 in spacing #4 Lacer Bars 4.0 in 15.0 in 120.0 in 4.5 in 20.0 in 6.0 in 120.0 in 6.0 in #5 bars @ 6 in spacing #4 bars @ 12 in spacing 6.25 in 4.5 in 6.0 in 72.0 in 15.0 in #4 Lacer Bars 7.25 in #4 bars @ 12 in spacing #5 bars @ 6 in spacing Read the entire page →
From page 294... ... 295 Figure 9.2.6: WT-2 transverse joint specimen Figure 9.2.7: WT-3 transverse joint specimen 4.5 in 6.0 in 72.0 in 15.0 in #4 Lacer Bars 7.25 in #4 bars @ 12 in spacing #5 bars @ 6 in spacing 4.5 in 72.0 in 15.0 in 4.0 in #4 Lacer Bars #5 bars @ 6 in spacing #4 bars @ 12 in spacing 7.25 in Read the entire page →
From page 295... ... 296 Figure 9.2.8: WT-4 transverse joint specimen 9.2.1. Experimental Setup and Instrumentation The Phase I test setups and instrumentation described in Section 9.1.2 were also used for the Phase II test series. Read the entire page →
From page 296... ... 297 Figure 9.2.9: Strain gage configuration for WB-3 and WT-3 Figure 9.2.10: Strain gage configuration for WB-2, WT-2, WB-4, and WT-4 UB-3 UB-4 UB-2 4-1 4-2 4-3 3-13-23-3 2-1 2-2 2-3 LB1-2 LB1-1 LB-2LB-1 UB-5 UB-4 UB-3 UB-2 UB-1 4"2"2" 2"2"4" 4" 2"4" 2" 4-34-24-1 3-13-23-3 2-1 2-2 2-3 LB1-2 LB1-1 LB-2LB-1 UB-5 UB-4 UB-3 UB-2 UB-1 6" 2" 2" 6" 6" 2" 2" 2"2"6" UB-2 UB-4 UB-3 Read the entire page →
From page 297... ... 298 9.2.2. Material Testing Concrete Testing The longitudinal joint specimens were cast on September 16, 2009. Read the entire page →
From page 298... ... 299 Table 9.2.3: Concrete compressive strengths (transverse joint specimens) Cylinder 7-Day Test Day of Test 28-Day Test ID (psi) Read the entire page →
From page 299... ... 300 Table 9.2.4: Service moments M+ M- WB-1, WB-2, WB-3 WB-4 WB-1, WB-2, WB-3 WB-4 (kip-ft) Read the entire page →
From page 300... ... 301 Figure 9.2.11: Moment versus deflection Figure 9.2.12: Moment-versus-curvature From Figures 9.2.11 and 9.2.12, the behavior of each specimen can be compared to one another. Because ACI 318-08 does not provide a specific method for calculating the moment capacity for a staggered U-bar detail at the joint, two continuously reinforced beam sections were analyzed using two different steel reinforcement patterns: (1) Read the entire page →
From page 301... ... 302 longitudinal joint specimen with three U bars. The cross-sections used in theoretical calculations are displayed in Figures 9.2.13 and 9.2.14. Read the entire page →
From page 307... ... 308 Figure 9.2.17: Material properties used in Response 2000 Because the U-bars were staggered in the test specimens, the moment capacities, curvatures, and deflections differed from a continuously reinforced section. The joint was a combination of two U-bars, As=1.24 in 2, and three U-bars, As=1.86 in 2. Read the entire page →
From page 308... ... 309 Table 9.2.5: Flexural test results, nominal moments (Mn Specimen ID ) Read the entire page →
From page 309... ... 310 Flexural Specimen Behavior (Longitudinal Joint Behavior) According to the data, each specimen cracked at the following moments: WB-1 cracked at approximately 5.9 kip-ft; WB-2 cracked at 2.4 kip-ft; WB-3 cracked at 4.7 kip-ft; and WB-4 cracked at 6.8 kip-ft. Read the entire page →
From page 311... ... 312 Strain Gage Data (Longitudinal Joint Behavior) As discussed in Section 9.2.1, strain gages were applied to the reinforcement to determine whether the reinforcement yielded within the overlap length. Read the entire page →
From page 314... ... 315 Table 9.2.7: Tensile test results Specimen ID Tensile Capacity Deflection (kip) Read the entire page →
From page 315... ... 316 Figure 9.2.20: Load versus deflection Tensile Specimen Behavior (Transverse Joint Behavior) For all specimens, the first visible surface cracks developed in the transverse direction and were located outside the joint zone. Read the entire page →
From page 316... ... 317 Diagonal cracks appeared in the joint as the specimens approached capacity. These diagonal cracks propagated toward the first transverse cracks that developed in the joint. Read the entire page →
From page 318... ... 319 Figure 9.2.22: Deformation of lacer bar Tensile Crack Widths at Service Level Loading (Transverse Joint Behavior) As calculated in Section 9.1, the tensile service load for the U-bar detail was determined to be 55.1 kips if the yield strength of reinforcement was 75.0 ksi. Read the entire page →
From page 319... ... 320 Figure 9.2.23: Crack comparator used to measure tension crack widths Strain Gage Data (Transverse Joint Behavior) In Figure 9.2.24, the total applied force versus strain curves for each gage location were plotted for the transverse joint tests. Read the entire page →
From page 323... ... 324 flexural capacity was decreased by 17.8%, and the tensile capacity was decreased by 18.9%. Increasing the spacing of the U-bar reinforcement from 4.5 to 6 in. Read the entire page →
From page 324... ... 325 In the Phase II tests, another six specimens with the U-bar detail were tested, three in flexure and three in tension, to investigate effects of variables including overlap lengths, rebar spacings, and concrete strengths. Based on results of the Phase II tests, the following conclusions can be made. Read the entire page →

From page 247...

... 248 Chapter 9 Flange/Deck Connection: Selection of Most Promising Connection Detail through Two-Phase Experimental Investigation 9.0 Introduction to Two-Phase Experimental Investigation to Finalize Connection Concept Detail for Further Study The headed bar detail and deformed wire reinforcement (DWR) and stainless steel (SS)