Seismic Behaviour of PC-encased HCSC Composite Shear Walls under Vertical Tension and Horizontal Cyclic Loading

Abstract

ABSTRACT The integrity of precast concrete (PC) shear walls depends strongly on the structural measures and construction quality of the reinforcement connections, which impedes complete equivalence with cast-in-place connections, the construction height, and the applicability to high-seismicity regions. The seismic behaviour of hybrid precast concrete-encased concrete-filled twin steel tube (PCCS)-reinforced composite shear walls was investigated under combined vertical tension and horizontal cyclic loading. Embedded cast-in-place high-strength concrete-filled thin-walled twin steel tube cores (HCSCs) were used to position a PC shear wall panel and stiffen vertical connections for improved load-bearing. Quasi-static cyclic tests were conducted on six PCCS composite shear wall specimens with a shear-span ratio of 1.84 to investigate how the HCSC cross-section ratio, out-of-plane eccentricity, and initial axial tension affected the seismic performance. The specimens failed by combined shear-bending, and the HCSCs served as reliable connections and reinforcements. The specimens exhibited relatively high load-bearing capacities, complete hysteretic curves, good deformation and energy dissipation, and large residual stiffnesses at failure. Shear deformation contributed approximately 21% to the total lateral displacement. The average ultimate drift ratio of 1/42 and average ductility factor of 5.0 of the specimens demonstrated excellent assembly integrity. A parametric analysis of the bearing capacity of the cross-section revealed that as the HCSC cross-section ratio increased, both the shear capacity and lateral stiffness increased, where the latter produced a rapid decrease in the deformation curvature. The shear capacity decreased with increasing initial axial tension and out-of-plane eccentricity. The deformation curvature was increased using an appropriate axial tension level and deteriorated by the out-of-plane eccentricity.