# Flexural Performance of Reinforced Concrete Members with Steel Bars
## 3 Results  
### Flexural Member Experiment Results  
The flexural member experiment was conducted with two simple points of support, and the displacement of the centre was measured. In addition, the widths of the cracks in the centre were measured for a displacement of 5 mm. The experiment was conducted considering the typical yield of rebar for all subjects. The initial crack occurred in the centre of the subject; further, as the load increased, the number of cracks in the centre and the crack width increased. After reaching the yield load, sinusoidal cracks occurred at both ends. Upon surpassing the yield load, the displacement increased rapidly, and the experiment was terminated. The fracture of the subject was bent in a destructive manner and occurred in the pure bending section of the subject for the first time, wherein cracks progress from the centre to the supporting point. The overall crack patterns in all subjects were similar. The initial crack generation, yield load, and maximum load for each member are listed in Table 5.  
### Flexural Member Experiment Results  
For the flexural member experiment, two-point loading was performed and the displacement at the centre was measured. In addition, the widths of the cracks at the centre were measured for a displacement of 5 mm, as shown in Figure 4.  
The experiment was conducted considering the typical yield of steel bars for every specimen. The initial cracks were generated at the centre of the specimen. The number and width of the cracks at the centre increased with the load. Diagonal cracks were generated at both ends after reaching the yield load. Upon surpassing the yield load, the displacement increased sharply as the load gradually increased, and the experiment was terminated. The failure mode of the specimen was a flexural failure, and the cracking pattern also indicated the flexural failure, as a vertical crack occurred first in the pure bending section at the centre of the specimen, following which the crack progressed from the centre to the support point. All specimens showed similar overall cracking modes in general. The load-displacement curves of each member and the load-strain curves of concrete and steel bars are shown in Figures 5-7. The initial crack, yield load, and maximum load results are summarised in Table 6.  
For the 21-400-1.0 experiment, compressive strength of 21 MPa of concrete, yield strength of 400 MPa of tensile rebar, and a tensile rebar ratio were considered. The load-displacement curves and the load-strain curves of rebar and concrete in the 21-400-1.0 specimen are shown in Figures 5a and 6a. The initial crack in the 21-400-1.0 experiment resulted in an increase in the number of cracks and the crack width, along with an increase in the load. At the time of the initial crack, the load was 32.5 kN, with a displacement of 1.7 mm. The yield load was 287.3 kN, with a displacement of 27.7 mm, and the maximum  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**No**} & \multirow{2}{*}{**Experiment Name**} & \multicolumn{2}{c}{**Initial Crack**} & \multicolumn{2}{c}{**Yield Load**} & \multicolumn{2}{c}{**Maximum Load**} \\ \cline{3-8}  & & **Load** & **Displacement** & **Load** & **Displacement** & **Load** & **Displacement** \\  & & **(kN)** & **(mm)** & **(kN)** & **(mm)** & **(kN)** & **(mm)** \\ \hline
1 & 21-400-1.0 & 32.5 & 1.7 & 287.3 & 27.7 & 294.8 & 30.1 \\
2 & 21-400-0.75 & 18.8 & 1.1 & 207.0 & 25.1 & 213.0 & 27.7 \\
3 & 21-400-0.5 & 21.8 & 1.  
load was 294.8 kN, with a displacement of 30.1 mm. After reaching the maximum load, the displacement rapidly increased as the load decreased, ending the experiment. Figure 7a shows the number of cracks and cracks after the end of the 21-400-1.0 experiment, along with the crack width between the weight points for each 5 mm displacement at the centre of the subject.