Seismic behavior of multiple reinforcement, high-strength concrete columns: experimental and theoretical analysis

This study investigates the seismic performance of multiple reinforcement, high-strength concrete (MRHSC) columns that are characterized by multiple transverse and longitudinal reinforcements in core areas. Eight MRHSC columns were designed and subjected to a low cycle, reversed loading test. The response, including the failure modes, hysteretic behavior, lateral bearing capacity, and displacement ductility, was analyzed. The effects of the axial compression ratio, stirrup form, and stirrup spacing of the central reinforcement configuration on the seismic performance of the columns were studied. Furthermore, an analytical model was developed to predict the backbone force-displacement curves of the MRHSC columns. The test results showed that these columns experienced two failure modes: shear failure and flexure-shear failure. As the axial compression ratio increased, the bearing capacity increased significantly, whereas the deformation capacity and ductility decreased. A decrease in the spacing of central transverse reinforcements improved the ductility and delayed the degradation of load-bearing capacity. The proposed analytical model can accurately predict the lateral force and deformations of MRHSC columns.