Behavior of Precast Concrete Shear Walls for Seismic Regions: Comparison of Hybrid and Emulative Specimens

TLDR

The study examines lateral load behavior of two 0.40‑scale hybrid precast concrete shear walls and a third emulative wall designed to mimic monolithic cast‑in‑place RC shear walls. The walls, sharing identical geometry, were built by placing rectangular precast panels across horizontal joints; hybrid walls incorporated mild steel bars (Grade 400) and high‑strength unbonded post‑tensioning strands for lateral resistance, while the emulative wall used only mild steel bars, with base‑joint bars designed to yield for energy dissipation and PT strands in hybrids reducing residual displacements, and splicing details varied between Type II mechanical splices and continuous bars grouted into the foundation. The emulative wall, lacking post‑tensioning, exhibited large residual uplift, excessive slip, and strength loss, while the hybrid wall with Type II splices suffered from mild‑steel bar pullout, but the hybrid wall with continuous bars demonstrated superior restoring, energy dissipation, and ductility over larger displacements, underscoring precast walls’ potential for seismic regions and highlighting critical detailing issues.

Abstract

This paper discusses the lateral load behavior of two, 0.40-scale, hybrid, precast concrete shear wall test specimens and the behavior of a third precast specimen designed to emulate monolithic cast-in-place RC shear walls. The walls had identical overall geometry and were constructed by placing rectangular precast panels across horizontal joints. The hybrid walls used mild steel bars [Grade 400 (U.S. Grade 60)] and high-strength unbonded posttensioning (PT) strands for lateral resistance, whereas the emulative wall used only mild steel bars. The mild steel bars crossing the base joint were designed to yield and provide energy dissipation, with the PT steel in the hybrid walls reducing the residual displacements of the structure. The mild steel bars at the base of the emulative wall and one of the hybrid walls used Type II mechanical splices, while the other hybrid wall used continuous bars grouted into the foundation. Because of the lack of PT steel, the emulative wall developed a large residual uplift at the base joint, resulting in excessive horizontal slip and strength degradation. The behavior of the hybrid wall with Type II splices was also limited, which occurred because of the pullout of the mild steel bars. In contrast, the hybrid wall with continuous mild steel bars showed superior restoring, energy dissipation, and ductile behavior over larger lateral displacements. The results show the potential for the use of precast walls in seismic regions, while also revealing important detailing considerations.