Retrofitting seismically damaged steel sections encased concrete composite walls using externally bonded CFRP strips

Abstract

Concrete shear wall encased with steel sections were widely used in high rise buildings due to its high lateral stiffness, ductility, and energy dissipation capacity. However, to date, little studies were conducted on retrofitting seismically damaged steel-concrete composite (SCC) walls to recover their lateral load resisting capacity. One of the possible retrofitting methods is to use Carbon Fiber Reinforced Polymers (CFRP) strips to retrofit SCC walls after earthquake. However, its efficiency was unclear. For this purpose, four SCC walls were first tested to failure under cyclic lateral loads with subsequently repairmen and re-testing aiming to investigate the efficiency of this retrofitting technique. The load causing the first crack, crack pattern, yield load, and peak load were measured and compared. It was found that replacing buckled rebar and applying proper CFRP repairing scheme could fully recover the seismic resistance of damaged SCC walls. However, purely rely on CFRP repairing schemes without buckled rebar replacement will not achieve full recover of the capacity of the SCC walls. However, specimens retrofitted by CFRP schemes alone can delay the process of strength and stiffness degradation than that of counterpart without retrofitting, which resulted in enhancement of relatively larger drift ratio.