Cyclic behavior of high-strength concrete shear walls with high-strength reinforcements and boundary CFST columns

Abstract

The reinforced concrete shear wall with boundary concrete-filled steel tube (CFST) columns features high lateral strength and seismic ductility. Combining the use of high-strength concrete and high-strength reinforcements for this kind of composite shear wall has attracted widespread attention recently. To investigate the cyclic performance of high-strength concrete shear walls with high-strength steel bars and boundary CFST columns, five specimens with varying concrete strengths, steel tube types, steel fiber ratios, and strengthening measures using bottom steel plates were tested under constant axial loading combined with lateral cyclic loading. The test failure modes and the measured components of the flexural and shear displacements indicated flexural-dominated failure patterns for all the shear walls, where the shear connectors ensured a reliable connection between the boundary CFST columns and the wall web. Although the high-strength concrete and high-strength reinforcements functioned well together, the reasonable material strength matching between concrete and steel bars and the stiffness matching between wall web and boundary elements should also be considered in design. The incorporated steel fibers alleviated damage to the wall web and enhanced the wall's flexural deformation capacity. The addition of bottom double-skin steel plates to both sides of the wall web effectively increased the lateral strength, deformability, and reparability of a composite wall made of non-fiber-reinforced concrete. An analytical model was developed to evaluate the load-bearing capacity and verified by comparing the model predictions against test results.