Cyclic loading experiments on seismic performance of precast concrete superposed shear walls with CFST end columns

The seismic performance of precast concrete shear walls is a major concern when considering their application in earthquake-prone regions. To improve the seismic performance and constructability of conventional precast concrete superposed shear walls, an innovative design, termed Precast Concrete Superposed Shear Walls with CFST End Columns (PCSSWEC), has been proposed. Given the limited research on the seismic performance of PCSSWECs, cyclic loading experiments were conducted on three full-scale PCSSWEC specimens and one monolithic RC shear wall specimen. The design axial compression ratio (ACR) and the thickness of the steel tube were employed as research variables. Experimental observations and results gave a comprehensive view of the hysteretic behavior of PCSSWECs, reflecting a favorable seismic performance (in terms of failure modes, global and local damage, force-displacement responses, load-bearing capacity, stiffness and strength degradation, deformability, ductility, and energy dissipation capacity). The experiment also revealed significant differences between PCSSWECs and monolithic RC shear walls in concrete crack development and deformation characteristics, confirming that the CFST columns and the wall panel could work together until the failure phase. Moderately increasing the ACR (0.3-0.5) was beneficial for PCSSWECs. However, increasing the steel tube thickness (3.5 mm-5.0 mm) could lead to unfavorable degradation in strength and stiffness and weaken ductility. In addition, a simplified method was proposed to evaluate the flexural strength of PCSSWECs.