## 4 Out-of-Plane Flexural Behavior of SC Composite Beams with Different Shear Connection Ratios
### V/V\({}_{u}\)  
\(V\) represents the interfacial shear of the tie-bar, and \(V_{u}\) represents the shear capacity of the tie-bar. The \(V/V_{u}\) versus displacement curves of the SC composite beams with different shear connection ratios are shown in Figure 11. The ratio of \(V\) versus \(V_{u}\) increases with the increase in displacement, and the uneven degree of interfacial shear distribution increases with the increase in the shear connection ratio.  
Figure 10: Internal force-displacement curves of SC composite beams with different shear connection ratio.  
For the SC composite beam with a 0.5 shear connection ratio, when the tie-bar fractures, the \(V\) of the tie-bar decreases rapidly. When the SC composite beam reaches ultimate displacement, the \(V/V_{u}\) versus displacement curve is approximately trapezoidal. The \(V\) of the first five rows of tie-bars increases significantly with the increase in span. The other tie-bars have similar interfacial shear force. For the SC composite beam with a 0.7 shear connection ratio, the \(V\) of the first three rows of tie-bars increases significantly with the increase in span. For the SC composite beam with a low shear connection ratio, the \(V\) of the tie-bars close to the maximum bending moment could be significantly lower than the \(V_{u}\) of tie-bars due to the limitation of interfacial slip. Meanwhile, the \(V\) of the tie-bars far away from the maximum bending moment could prematurely reach \(V_{u}\).  
For the SC composite beam with 1.0 shear connection ratio, the \(V/V_{u}\) versus displacement curve is also approximately trapezoidal. However, for the SC composite beam with a 1.3 shear connection ratio, the \(V/V_{u}\) versus displacement curve is approximately bilinear,  
Figure 11: \(V/V_{u}\)—displacement curves of SC composite beams with different shear connection ratios.  
and the \(V\) of the first five rows of tie-bars increases significantly with the increase in span. The \(V\) of the tie-bars far away from the fixed end increases slightly with the increase in span. For the middle shear connection ratio, the \(V/V_{u}\) versus displacement curves are significantly variable. Meanwhile, the \(V\) of tie-bars close to the maximum bending moment are also significantly lower than the \(V_{u}\) of the tie-bars.  
For the SC composite beam with a 1.7 shear connection ratio, the \(V/V_{u}\) versus displacement curve could be divided into three parts. In the first part, close to the fixed end, the \(V\) of the tie-bars increases significantly with the increase in span. In the second part, at the middle of the SC composite beam, the \(V\) of the tie-bars increases slightly with the increase in span. In the third part, close to the free end, the \(V\) of the tie-bars increases rapidly with the increase in span, which could be due to the influence of concentrated loading. The \(V/V_{u}\) versus displacement curve in the first part and the second part is approximately parabolic, which is similar to that of the SC composite beam with a 2.0 shear connection ratio. For a high shear connection ratio, the \(V\) of most tie-bars are lower than \(\rm{V_{u}}\), and the uneven degree of interfacial shear distribution is more significant.