Seismic performance of cross-shaped columns with 500 MPa grade reinforcing steel bars

Abstract

Based on the experimental research on three cross-shaped columns with 500 MPa grade reinforcing steel bars, the contrastive analysis is made on failure mode, bearing capacity and displacement ductility of each column specimens with different stirrup spacing under the identical axial compression ratio. The research shows that the longitudinal bars yield before spalling of core concrete and high-strength stirrups can provide significant confinement. Decreasing stirrup spacing can significantly improve the ductility of the specimens. Meanwhile, based on the fibre element in the OpenSees software, the mechanical characteristics of the specimens are stimulated using fined constitutive relation of materials. The test results are well consistent with the calculated results. The effects of the longitudinal bar strength, the stirrup strength and stirrup spacing on the mechanical performance of the specimens are investigated in this paper, and the results show that the decrease of the stirrup spacing and increase of the stirrup strength can significantly improve the bearing capacity, ultimate displacement and ductility of the specimens but has little effect on the yield displacement. The increase of the longitudinal bar strength can significantly increase the bearing capacity, yield displacement and ultimate displacement of specimens, but the displacement ductility factor will be decreased slightly.