## 3 Experimental Variables and Results
### Experimental Results and Analysis  
The load-deflection relationships based on the deflection measured during the application of loads on the concrete panels were compared. Table 5 provides a summary of the experimental variables and results for the concrete panels. The initial cracking load (P\({}_{\text{cr}}\)) was determined based on the load at the end of the initial linear section and observation of initial cracks by the naked eye during load application. The point at which the load shows nonlinear behavior (after a monotonic increase) is denoted as the yield load (P\({}_{\text{y}}\)) state. The ultimate load (P\({}_{\text{u}}\)) was calculated as the maximum load in the load-deflection relationship. The load-deflection relationships for the UHPFRC-F series with steel fiber contents of 1.0%, 1.5%, and 2.0% are presented in Figure 10. The initial cracking loads for experimental members F1.0, F1.5, and F2.0 were 78.6, 79.8, and 79.9 kN, respectively, with \(\Delta\)cr values of 1.3, 1.1, and 1.1 mm, respectively. Since no rebar was embedded, yield loads were not examined. A small initial crack developed in the center cross-section of the panel member, and the load progressively increased. The ultimate loads (Pu) were 182.7, 302.3, and \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Series**} & \multirow{2}{*}{**Panel**} & \multicolumn{3}{c}{**Initial Cracking**} & \multicolumn{3}{c}{**Yield State**} & \multicolumn{3}{c}{**Ultimate State**} \\ \cline{3-11}  & & **P\({}_{\text{cr}}\)** & **M\({}_{\text{cr}}\)** & **\(\Delta_{\text{cr}}\)** & **P\({}_{\text{y}}\)** & **M\({}_{\text{y}}\)** & **\(\Delta_{\text{y}}\)** & **P\({}_{\text{u}}\)** & **M\({}_{\text{u}}\)** & **\(\Delta_{\text{u}}\)** \\  & & **(kN)** & **(kNm)** & **(mm)** & **(kN)** & **(kNm)** & **(mm)** & **(kN)** & **(kNm)** & **(mm)** \\ \hline RC & N24-H20-R1 & 123.3 & 18.5 & 1.6 & 201.0 & 30.1 & 3.0 & 244.1 & 36.6 & 10.3 \\ \hline \multirow{3}{*}{UHPFRC-F} & S120-H20-F1.0 & 78.6 & 11.8 & 1.3 & - & - & - & 182.7 & 27.4 & 1.8 \\ \cline{2-11}  & S120-H20-F1.5 & 79.8 & 23.5 & 1.1 & - & - & - & 302.3 & 45.3 & 3.4 \\ \cline{2-11}  & S120-H20-F2.0 & 79.9 & 12.0 & 1.1 & - & - & - & 448.2 & 67.2 & 4.6 \\ \hline \multirow{3}{*}{UHPFRC-T} & S120-H12-R1 & 80.5 & 12.1 & 1.2 & 215.3 & 32.3 & 3.5 & 247.7 & 37.2 & 8.5 \\ \cline{2-11}  & S120-H12-R2 & 120.9 & 18.1 & 1.5 & 269.8 & 40.5 & 4.7 & 288.3 & 43.2 & 7.4 \\ \cline{2-11}  & S120-H12-R3 & 96.2 & 14.4 & 1.1 & 322.3 & 48.3 & 5.5 & 349.8 & 52.5 & 8.6 \\ \hline \multirow{3}{*}{UHPFRC-I} & SH120-H20-R1 & 99.1 & 14.9 & 1.2 & 334.5 & 50.2 & 4.8 & 339.3 & 50.9 & 6 \\ \cline{2-11}  & SH120-H20-R2 & 95.2 & 14.3 & 1.3 & 363.0 & 54.5 & 4 & 374.5 & 56.2 & 5.1 \\ \cline{2-11}  & SH120-H20-R3 & 70.9 & 10.7 & 1.0 & - & - & 424.0 & 63.6 & 5.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Test results. Figure 9: Instrumentation used for the panel. 448.2 kN, with deflections of 1.8, 3.4, and 4.6 mm, respectively. The analysis revealed that the ultimate load increased by 1.65 and 2.45 times compared to that of the F1.0 member as the steel fiber content increased. The load-carrying capacity of the panel member increased with increasing steel fiber content. After the ultimate load was reached, the load exhibited a gradual decrease, which was attributed to the ductility effect of the steel fibers, even without embedded rebar. The analysis of the load-deflection relationships for the UHPFRC-T series based on the amount of rebar yielded the following results. The initial cracking loads for experimental members S120-H12-R1, S120-H12-R2, and S120-H12-R3 were 80.5, 120.9, and 96.2 kN, respectively. Correspondingly, the measured deflections were 1.2, 1.5, and 1.1 mm (Figure 11). Initial cracking was observed on the lower surface of the flexural section, and as the load increased, these cracks tended to propagate vertically along the upper surface of the member. For the S120-H12-R3 panel, which had the highest rebar content, the ultimate load was 349.8 kN, with a deflection of 8.6 mm.