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15 tudinal bar extending through a hole in the cap beam flange into the deck are compared with the strain profiles of the opposite bar which was terminated in the connection region next to the flange near the deck (i.e., was not extended into the bridge deck). The comparison is shown for two different load steps, 0.5 Fy and = 1.0. Most of the load is seen to be dissipated near the column-to-cap beam interface (embed- ment length = 0 in.) for the smaller load step for both bars, while both bars exhibit a more linear distribution at the higher load step. The good comparison indicates that extension of the bars into the bridge deck is not necessary if adequate anchorage length is provided within the connection region. The dilatation of the cap beam in the connection region was investigated to determine the adequacy of the steel box beam in providing confinement. This investigation revealed that, although the cap beam behaved elastically throughout the test, the dilatation began increasing more drastically at loads exceeding 1.0 Fy, indicating that the cap beam by itself would perhaps become ineffective in providing confinement at higher loads and that spiral reinforcement in the connec- tion region is required for confinement at higher loads. 2.5.2 Simulated Service Load Testing Four simulated service load tests were conducted as illus- trated in Figure 14: SLC1, SLC2, SLC3, and SLC4 with two different support conditions (i.e., all girders supported and only exterior girders supported) and two types of loading (i.e., vertical and lateral). The primary purpose of these tests was to investigate the distribution of moments between the inte- rior and exterior girders and to validate the analytical model by comparing the analytical results to test results. Because of the small magnitude of loads and strains for these four load conditions, three load conditions from the seis- mic loading with similar support and load configurations were also used in the analysis of the girder distribution factors. Girder strains were used to determine the experimental load distribution. Analytical models were used to predict the load distribution for loading in both the vertical and horizontal directions. Comparisons of the experimental and analytical load distributions from SPC1 and SPC2 are shown in Tables 1 and 2. The strain in the flanges of the interior and exterior gird- ers is shown in Figure 15. The comparisons for SLC1 and SLC3 are very good for both specimens. However, in both Figure 10. Tension side of the specimens the experimental distribution for SLC2 and SLC4 column in the push loading revealed a significant percentage of the load being carried by direction after seismic testing the interior girders, whereas the analytical model indicates a (SPC2). distribution of 100 percent to the exterior girders. At least two explanations are possible. First, the experimentally based load ductility = 3.0 because of slippage of the extreme bar that distributions may not be accurate because of experimental was not mechanically anchored. errors at the low strain levels for these two tests. Second, and To investigate the necessity of extending the column lon- much more likely, the transverse stiffness of the concrete slab gitudinal bars into the bridge deck, the strains measured on and end diaphragm distributed forces to the interior girders the longitudinal bars in the connection region were investi- even though they were not supported. The analytical model did gated. In Figure 13, the strain profiles from SPC1 of a longi- not account for transverse stiffness between the girders.

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16 400 300 Lateral force resistance (kN) 200 100 0 -100 -200 -300 -400 -250 -150 -50 50 150 250 Displacement at column end (mm) (a) Entire simulated seismic test 400 = 1.5 3.0 4.0 300 Lateral force resistance (kN) 200 100 0 -100 -200 -300 Experimental = -4.0 -3.0 -2.0 -1.0 Predicted -400 -200 -150 -100 -50 0 50 100 150 200 Displacement at column end (mm) (b) Up to = 4.0 Figure 11. Column lateral force-displacement response of SPC1 (1 kN = 0.225 kips, 1 mm = 0.039 in.).

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400 300 Lateral force resistance (kN) 200 100 0 -100 -200 -300 -400 -250 -200 -150 -100 -50 0 50 100 150 200 250 Displacement at column end (mm) (a) Entire seismic test 400 = 1.5 3.0 4.0 300 Lateral force resistance (kN) 200 100 0 -100 -200 -300 Experimental = -4.0 Predicted -3.0 -2.0 -1.0 -400 -200 -150 -100 -50 0 50 100 150 200 Displacement at column end (mm) (b) Up to = 4.0 Figure 12. Experimental force-displacement response of SPC2 (1 kN = 0.225 kips, 1 in. = 25.4 in.). Microstrain 0 500 1000 1500 2000 2500 0 Distance from the cap beam interface (mm) 100 200 -1.0 300 -1.0 Fy (short) -0.75 Fy (short) 400 -0.5 Fy (short) -0.25 Fy (short) +0.25 Fy (long) 500 +0.5 Fy (long) +0.75 Fy (long) 600 1.0 Fy (long) 1.0 700 Figure 13. Tension strain profiles for the reinforcing bars (SPC1).

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P = 90 kN (20 kips) P = 90 kN (20 kips) (a) SLC1 (b) SLC2 H = 45 kN (10 kips) H = 45 kN (10 kips) (c) SLC3 (d) SLC4 Figure 14. Service-load test condition. TABLE 1 Comparison of experimental TABLE 2 Comparison of experimental and analytical load distributions (SPC1) and analytical load distributions (SPC2) Load Distributions Load distributions Load Condition Girder Load Condition Girder Average Experimental Analytical Average Experimental Analytical Exterior 50% 45% Exterior 47% 46% SLC1 SLC1 Interior 50% 55% Interior 53% 54% Exterior 76% 100% Exterior 75% 100% SLC2 SLC2 Interior 24% 0% Interior 25% 0% Exterior 35% 28% Exterior 32% 30% SLC3 SLC3 Interior 65% 72% Interior 68% 70% Exterior 72% 100% Exterior 60% 100% SLC4 SLC4 Interior 28% 0% Interior 40% 0% 60 30 Microstrain SLC1 0 SLC2 SLC3 -30 SLC4 -60 -90 (a) Strains at gages S3 and S11 for SLC1 through SLC4 S1, S3 S9, S11 Exterior Interior Girder Girder (b) Cross-sectional view showing the relative location for strain gages S1, S3, S9, and S11 Figure 15. Top flange strains for the exterior and interior girders for SLC1 through SLC4.