Behaviour of steel tube reinforced-concrete short bridge columns under cyclic loading

Abstract

The results of an experimental study focused on the cyclic shear behaviour of steel tube reinforced-concrete (STRC) short bridge columns are presented. Seven STRC column specimens were tested under constant axial load and cyclic-reversed lateral displacement to investigate the effects of the axial load ratio, volumetric stirrup ratio, longitudinal steel ratio, sectional steel tube ratio and shear span ratio. An additional reinforced-concrete (RC) short column was also tested to evaluate the effectiveness of the steel tube at enhancing the column behaviour. Damage progression and failure modes of the specimens are described, along with a detailed discussion on their seismic indexes with regard to shear strength, ductility, stiffness degradation and energy dissipation. The test results demonstrated improved seismic resistance and mitigated damage extent for the STRC specimens relative to the RC counterpart. It was also found that the STRC short bridge columns with rational structural configurations possessed satisfactory deformability, ductility and energy dissipation capacity and can thus be utilised in regions of moderate to high seismicity. Based on the test results, a simplified superimposition model and the corresponding expressions are developed for shear strength prediction of STRC short bridge columns.