Hysteresis behavior of precast concrete composite shear walls with improved vertical connections

Abstract

Precast concrete composite shear walls (PCCSWs) is a new type of precast shear wall with single- or double-layer precast panels and a cast-in-place (CIP) concrete layer (i.e., precast single wall, PSW, or precast double wall, PDW). PCCSWs could form a solid concrete structure with a shorter superstructure construction time. Therefore, these walls have become a promising precast concrete structural system for high-rise buildings worldwide. The objective of this study was to investigate the hysteresis behavior of PDWs and PSWs with improved vertical connections from the perspectives of efficiency in load transfer and simplicity in construction for applications in seismic zones. Low-reversed cyclic testing was conducted for six full-scale PCCSWs with two different axial load ratios (0.09 and 0.23). The six walls included four PDWs with two types of vertical connections (double-row spiral-confined lap connection and single-row protruding rebar lap connection) and two PSWs with a spiral-confined lap connection. The results revealed that the specimens exhibited monolithic behavior and flexural-shear failure, as expected. The difference in load capacity between the PCCSWs and CIP walls was less than 10%. All the walls had plump hysteresis loops and adequate energy dissipation performance. PDWs with the double-row spiral-confined lap connection had the highest ductility ratio (4.57 for the low axial ratio, 3.50 for the high axial ratio). The single-row protruding rebar lap connection enabled the PDWs to demonstrate relatively good ductile behavior (3.85 for the low axial ratio and 3.39 for the high axial ratio) and simple on-site construction. Although the PSWs had the lowest ductility, the ductility was comparable to that of the CIP wall with low and high axial ratios. All the specimens had a similar tendency in terms of the backbone curves and stiffness degradation. Accordingly, a trilinear degraded restoring force model was developed for different PCCSWs by regression.