Seismic Performance of In-Plane Loaded Modular Squat Shear Walls and the Influence of Post-Cast Strips

This study investigates modular low-rise shear walls by designing and fabricating four in-plane loaded specimens at a scale ratio of 1:2.7. Quasi-static low-cycle reversed loading tests combined with numerical simulations were systematically conducted to examine the effects of the type and location of post-cast strips on the seismic performance of shear walls. The experimental program comparatively analyzed crack development patterns, failure modes, and seismic performance indices of specimens with four construction configurations: without post-cast strips, with only a horizontal post-cast strip, with a horizontal post-cast strip combined with an eccentrically placed vertical post-cast strip, and with a horizontal post-cast strip combined with a centrally placed vertical post-cast strip. The results indicate that specimens without post-cast strips exhibit uniformly distributed and highly penetrative cracks, characterized by typical global shear failure. The horizontal post-cast strip restricts downward crack propagation, leading to crack concentration above the post-cast strip, whereas the combined arrangement of horizontal and vertical post-cast strips promotes dispersed crack development and significantly alleviates excessive local damage concentration. The specimen with a centrally located vertical post-cast strip exhibited the best overall seismic performance, characterized by full hysteretic curves, the largest cumulative energy dissipation, and the most gradual stiffness degradation, whereas the specimen with only a horizontal post-cast strip showed relatively poor energy dissipation capacity and ductility. The finite element model established based on the experimental results accurately reproduces the mechanical responses and failure characteristics of all specimens, validating the mechanism by which post-cast strips improve wall performance through stress dispersion and crack development regulation. The findings demonstrate that a rational arrangement of post-cast strips, particularly the adoption of a centrally placed vertical post-cast strip, can effectively enhance the seismic performance of modular low-rise shear walls.