## 3 Results and Analysis of the Tests
### Load-Displacement Relations and Overall Behaviors
Figure 8: Failure modes of the specimens: (**a**) ZS-12.8, (**b**) CS-12.8, and (**c**) CS-6.4. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Load (kN)**} & \multicolumn{3}{c}{**Drift Ratio (\%)**} & \multicolumn{3}{c}{**Secant**} & \multicolumn{3}{c}{**Mean Value of Normalized Strain in**} \\  & & & & & & & & \multicolumn{3}{c}{**Stiffness**} & \multicolumn{3}{c}{**Z-Type or clip-Type Shear Reinforcement 1 (\(\ell\)/\(\ell_{y}\))**} \\
**Specimen** & & & & & & & & & & & & & & & & \\ \cline{2-13}  & \(P_{y}\) & \(P_{test}\) & \(P_{u}\) & \(\delta_{y}\) & \(\delta_{test}\) & \(\delta_{u}\) & & \(K_{i}\) & \(K_{y}\) & **Z1 or C1 2** & **C2 3** & **Z1 or C1 2** & **C2 3** \\ \hline ZS-12.8 & 218 & 291 & 225 & 1.49 & 4.18 & 4.93 & 3.29 & 7.10 & 3.25 & 0.012 & - & 0.024 & - & 0.027 & - \\ CS-12.8 & 216 & 289 & 214 & 1.56 & 4.21 & 4.95 & 3.17 & 6.86 & 3.09 & 0.040 & 0.083 & 0.073 & 0.131 & 0.098 & 0.154 \\ CS-6.4 & 536 & 715 & 538 & 0.52 & 1.20 & 5.95 & 5.73 & 37.75 & 23.03 & 0.327 & 0.477 & 0.520 & 0.611 & 0.580 & 0.704 \\ \hline \hline \end{tabular} \(P_{y}\) is the yield load, calculated similar to Section 4.7 of ACI 374.28-13 [37], \(P_{test}\) is the measured maximum load, \(P_{u}\) is the load at failure or end of the test, \(\delta_{y}\) is the yield drift ratio at \(P_{test}\), \(\delta_{u}\) is the ultimate drift ratio at \(P_{u}\), \(K_{i}\) is the initial secant stiffness at 0.35% drift, and \(K_{y}\) is the secant stiffness at the yield drift \(\delta_{y}\) (=\(P_{y}/\delta_{y}\)). 1 The mean value of the strains in Z-type or clip-type shear reinforcement at the center and corner of the slab was used. The strain was normalized by the yield strain of the strains (\(\ell_{y}\) = 0.002383). 2.3 C1 and C2 are the strain of clip-type shear reinforcement, measured further away from and closer to the loading point, respectively.  
\end{table} 
Table 5: Summary of test results. In Specimens ZS-12.8 and CS-12.8 with Z-type and clip-type shear reinforcement, respectively, the load at each level (i.e., \(P_{y}\), \(P_{test}\), and \(P_{u}\)) and the corresponding drift ratios were almost identical. Thus, the ductility ratios were similar to each other (\(\delta_{u}/\delta_{y}=3.29\) and \(3.17\) in ZS-12.8 and CS-12.8, respectively). On the other hand, in Specim CS-6.8 with the shear-span ratio reduced to 6.4, the ductility ratio \(\delta_{u}/\delta_{y}\) was increased to 5.73, owing to the lower yield drift ratio \(\delta_{y}\) and larger ultimate drift ratio \(\delta_{u}\) than those of Specim CS-12.8 with a shear-to-span ratio of 12.8. Although all the specimens failed in flexure, in Specim CS-6.4 with the shear-to-span ratio reduced to 6.4, the strain of the clip-type shear reinforcement significantly increased due to the increased shear demand (Table 5). Figure 9 shows the displacement distributions measured by the LVDTs for ZS-12.8 for the service load, double the service load, and the load corresponding to the removal of the LVDTs. Under the service load, the specimen showed elastic deformations due to the noncracking concrete (Figures 7a and 9), which indicates that the structural safety of the PC slab system was secure under the construction load. Under double the service load considering a potential higher load, owing to the flexural cracking at the center of the PC slabs, the central displacement was increased by the decreased stiffness, resulting in a larger curvature at the center. This behavior was more significant under the maximum measurement (248 kN).