Rebar-Concrete Debonding Effect on the Seismic Performance of Reinforced Concrete Shear Walls: An Experimental Study

Abstract

Diverse criteria are taken for seismic design of shear walls due to their buckling failure in various regulations. Despite extensive studies on the topic, no practical mechanism has been widely adopted to effectively mitigate out-of-plane buckling in reinforced concrete shear walls. This study presents a novel approach to address this issue by experimentally investigating the effect of rebar-concrete debonding on the seismic performance of boundary elements in shear walls with minimum reinforcement. Plastic sleeves, applied to rebar at varying lengths (80 mm, 150 mm, and 220 mm), were used to induce debonding and thus modify the stress transfer mechanisms and crack propagation within the concrete. Five experimental samples of shear wall boundary element were designed and constructed with minimum reinforcement. Samples were subjected to non-uniform cyclic loading to study rebar debonding effect on crack distribution, rebar strain, and out-of-plane instability in boundary element. The results indicate that debonding leads to a reduction in the lateral stiffness of the boundary elements, postponing rebar buckling, and also provides a 12% enhancement in the tensile capacity of the rebar. Findings illustrate rebar-concrete debonding results in a reduction in lateral stiffness of boundary element. Similarly, comparing to a debonding free element, buckling member occurs at more minimal strains. It is also revealed that to prevent buckling, larger dimensions are required for sleeved sample. Moreover, robust evidence proved that increasing rebar debonding length enlarges crack width near sleeves, while sleeve length does not affect the first buckling or axial length of samples. This study provides a practical and innovative mechanism for addressing buckling challenges in minimum-reinforcement boundary elements, contributing to safer and more efficient structural design practices.