Seismic performance of damaged steel-concrete shear wall with prestressed diagonal bracing repaired by CFRP strips

Abstract

To investigate the seismic performance of damaged steel-concrete shear wall with prestressed diagonal bracing repaired by Carbon Fiber Reinforced Polymer (CFRP) strips. Three steel-concrete shear walls with diagonal bracing seriously damaged by low reversed cyclic loading were repaired by replacing damaged concrete, repairing diagonal bracing, restoring buckled reinforcements, and wrapping walls with CFRP strips. The seismic performance of the repaired specimens was evaluated using the same quasi-static test as for the original specimens. The seismic performance including the failure modes, deformation capacity, bearing capacity, energy dissipation, stiffness degradation, and bearing capacity degradation of the repaired specimens were researched in the study. Experimental results show that the used repair schemes effectively restore specimens’ bearing capacity, ductility, and energy dissipation, as well as enhancing deformation capacity. Applying an "X"-shaped CFRP repair scheme which aligned with the direction of the bracing can effectively compensates for the reductions of stiffness and bearing capacity due to cyclic loading. Compared to shear wall with smooth steel tubes as diagonal bracing, those with threaded reinforcements create a stronger mechanical interlocking effect between the bracing and concrete. This enhanced synergy interaction increases the effective shear resistance section in the midsection of the wall panel, thereby forming a more efficient diagonal load transfer mechanism. Therefore, shear damage can be avoided in the middle of the wall limb. Additionally, the study presents the theoretical calculation model for the original and the repaired shear walls, and the comparison of the calculation results with test results demonstrates that the calculation model has high computational accuracy.