Behavior of double skin composite core wall subject to biaxial cyclic loads

This study performed a biaxial cyclic test on scaled double skin composite (DSC) core wall. The core wall consisted of two C-shaped DSC shear walls and steel coupling beams (SCBs) connecting the walls. In particular, seismic behavior of the core wall subject to reversed biaxial cyclic load was investigated. The failure mode of the core wall mainly included its local buckling of steel faceplate, fracture of vertical butt welds, fracture of side plate, and concrete crushing at the corners of walls. The lateral shear resistance in its two directions was mutually coupled. Once loaded in one direction, lateral shear resistance in other direction compromised. Due to energy dissipation of SCBs in their Y-direction, hysteresis loop for Y-directional loading was fuller than that for X-directional loading, and equivalent damping ratio of X-direction was 31.91% greater than that of Y-direction at ultimate point. Their initial stiffness in X-direction without SCBs configuration was the highest, and ductility coefficient of X-and Y-directions was relatively close, within 4.63-5.47%. The strain distribution curves along DSC shear wall bottoms of core wall before its peak resistance showed plane section assumption was valid under biaxial lateral load. In particular, DSC core wall high-rise buildings were promoted in this study.