# Axial and Bending Bearing Capacity of Double-Steel-Concrete Composite Shear Walls
## 2 Experimental Results Analysis  
SC walls were conceived initially in Japan in the 1980s. Extensive research has been done in many countries to study the behavior and failure modes of SC walls. For example, [PERSON] et al. [7] tested three isolated walls and two coupled walls subjected to cyclic lateral loading. The specimen named DSCW1C in the test failed due to outward buckling of the steel plates and subsequent fracture of the vertical weld joint, followed by the filled concrete crushing and tie bars fracture. [PERSON] et al. [10] tested nine SC wall specimens with different shear span ratios. All the specimens failed due to the buckling of the steel plates and the filled concrete crushing. [PERSON] et al. [11] tested five slender rectangular wall specimens subjected to axial forces and lateral cyclic loading. The specimens failed in a flexural mode, characterized by local buckling of the steel tubes and plates, fracture of the steel tube, and concrete crushing at the wall base. Besides, the tested indicated that the average strain distribution of the surface steel plates agreed with the plane assumption within the range of 300 mm above the wall base. [PERSON] [12] tested nine SC wall specimens with the rectangular cross section. The experiment showed all the specimens failed due to the steel plate buckling and concrete crushing.  
The following conclusions are obtained by analyzing and summarizing the experimental results of the existing researches.  
* The bending failure characteristics of the SC wall are similar. Steel plate at the bottom of the SC wall yields first, followed by the buckling of the steel plate and concrete crushing. All SC wall failures are characterized by concrete crushing at embedded columns. When the studs are closely arranged, the steel plate at the bottom of the wall plate yields before buckling.
* Before the load reaches the peak, the average strain distribution of the surface steel plate at a certain height from the wall base is consistent with the plane assumption.  
The ratio of the stud spacing (B) to the steel plate thickness (t) has a significant effect on the steel plate buckling, as shown in Table 1. When the B/t ratio is within a certain range, local buckling occurs when the specimen near reaches the ultimate bearing capacity, and the buckling is accompanied by the pull-out of the concrete, indicating that the slippage between the surface steel plate and the filled concrete is small. When calculating the axial and bending bearing capacity of the SC wall, it is assumed that the steel plate and the concrete can be well unified without relative sliding, and when the SC wall reaches the ultimate bearing capacity, the steel plate does not buckle.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Reference** & **Specimen** & \(P_{\sigma}\) 1/\(P_{\sigma}\)2  & **The Limit of B/t** \\ \hline
[9] & W0 & 0.63 & buckling1  & 58.8 & 34 \\
[10] & SCW5 & 0.91 & buckling2 & 40 & 34 \\  & SCW1-1a & 0.95 & buckling2  & 13.3 & 33 \\  & SCW1-2b & 1.00 & buckling2 & 13.3 & 33 \\  & SCW1-3 & 0.91 & buckling2 & 13.3 & 33 \\  & SCW1-4 & 0.94 & buckling2 & 20 & 34 \\  & SCW1-5 & 0.92 & buckling2 & 10 & 32 \\  & SCW1-6 & 0.90 & buckling2 & 26.7 & 33 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The influence of \(B/t\) on local buckling of steel plates.  
Because the concrete in the SC shear wall is wrapped inside the steel plate, variables such as the ultimate compressive strain of concrete and the average strain of concrete in a certain height range are difficult to measure. To verify whether the strain conforms to the plane assumption in more cases and obtain the strain of the concrete inside the wall under ultimate load, a finite element simulation of the specimen in [12] was conducted. Calculations under various design axial compression ratios were carried out to supplement the test results.