Seismic behavior of composite encased steel plate shear wall using experimental and numerical methods

Composite shear walls (CSW) are one of the most desirable structural systems due to their high seismic efficiency, which encourages structural designers to use this system in high-rise buildings. Past studies widely investigated CSWs equipped with steel boundary elements, while limit investigations are available for CSWs with encased web steel plate and confined RC boundary elements. In this study, Composite Shear Walls with Web-encased Steel Plate (CSW-WSP) confined with dense stirrups at the boundary elements are assessed using both experimental and numerical methods. Using different lengths of steel plates, two CSW-WSPs were tested, and a finite element model (FE) was built and calibrated with the experimental tests. Furthermore, an extended parametric study was conducted to clarify the influence of the axial load ratio, reinforcement and steel plate ratios, confinement level, and aspect ratio on the lateral response. The results show that the proposed CSW-WSPs display a stable hysteresis lateral response, high energy dissipation with no strength degradation before 2.5 % drift ratio, and the ultimate lateral drift capacity of 3 % was obtained. Moreover, increasing the steel plate ratio from 1 % to 1.5 % improves the lateral strength, energy dissipation, and wall ductility by 13.24 %, 20 % and 12 %, respectively. The analytical results showed that increasing the axial load ratio more than 0.3 will severely decrease the wall drift capacity. The drift capacities of CSW-WSPs that conform to ACI-318-19 in terms of confinement were increased by 67 %, 40 % and 125 % for low, moderate, and high steel plate ratios, respectively.