# Tension Performance of Precast Bridge Deck Longitudinal Joints with Different Configurations
## 3 Results and Discussion  
The test results were compared using the following three characteristic values reported in Table 2: the initial cracking load, final load, and final relative displacement. An analysis of the load-relative displacement curves for each specimen was also conducted to determine the effects of each evaluated parameter. Figure 4: Test setup: (**a**) experimental view, (**b**) test setup for loading, and (**c**) measurement of relative displacement. Figure 5 compares the load-relative displacement curves of specimens J100-HB-SP and J150-HB-SP to evaluate the effects of joint widths of 100 mm and 150 mm, respectively. Table 2 shows that the initial cracking load decreased by more than 20%, the final load decreased by 18%, and the final relative displacement increased by 120% when the joint width increased from 100 mm to 150 mm. This suggests that the precast bridge deck joint exhibited less integral behavior as the joint width increased. Therefore, a smaller joint width of 100 mm is preferable to ensure that precast bridge deck joints exhibit high initial cracking and final loads. Figure 6 compares the load-relative displacement curves of J100-HB-SP and J100-NB-SP to evaluate the effects of the presence of steel rebar. As reported in Table 2, the initial cracking load for J100-NB-SP was considerably lower than that for J100-HB-SP, but both reached the final load value--although J100-NB-SP did so at a much larger final displacement (5.75 mm). Although the two specimens reached the final load, owing to the presence of the steel plate, the initial cracking load was 61% lower in the specimen without hooked rebars. This indicates that steel rebars are required to prevent the initial cracking of precast bridge deck joints. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Test Unit Name** & \
\begin{tabular}{c} **Initial Cracking** \\ **Load (kN)** \\ \end{tabular} & **Final Load (kN)** &
\begin{tabular}{c} **Final Relative** \\ **Displacement (mm)** \\ \end{tabular} \\ \hline J100-HB-SP & 490 & 800 & 2.34 \\ J150-HB-SP & 390 & 660 & 5.15 \\ J100-NB-SP & 190 & 800 & 5.75 \\ J0-LB-NP & 450 & 800 & 3.67 \\ J0-LB-SP & 460 & 800 & 3.23 \\ C-SB-NP & 450 & 800 & 3.12 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Test results. Figure 5: Load–relative displacement curves according to joint width. Figure 7 compares the load-relative displacement curves of J100-HB-SP and J0-LB-SP to evaluate the effects of rebar type and steel plate usage. Overall, the behavior of J0-LB-NP was similar to that of J100-HB-SP; however, as shown in Table 2, the final relative displacement of J0-LB-NP (3.67 mm) was approximately 56% larger than that of J100-HB-SP. It can be concluded that the looped rebars alone were insufficiently connected to the transfer load across the joint, whereas the combination of hooked top-layer rebars and the steel plate ensured integral structural performance. Therefore, hooked rebars are more effective than looped rebars in precast bridge deck joints. Figure 8 compares the load-relative displacement curves for J100-HB-SP and J0-LB-SP to evaluate the effects of the rebar type. The behavior of J0-LB-SP was similar to that of J100-HB-SP, and their characteristic loads (reported in Table 2) were also similar; however, the final relative displacement of J0-LB-SP (3.23 mm) was approximately 38% larger than that of J100-HB-SP. Overall, J0-LB-SP exhibited better structural performance than J0-LB-SP; however, its performance was poorer than that of J100-HB-SP, owing to the limited connectivity provided by the looped rebars. Thus, looped rebars provide less connectivity than hooked rebars, even when including a steel plate in the precast deck joint. Figure 6: Load–relative displacement curves with respect to the presence of hooked rebars. Figure 7: Load–relative displacement curves according to rebar type and presence of steel plate. Figure 9 compares the load-relative displacement curves of J100-HB-SP and C-SB-NP to evaluate the effects of the deck construction method.