Static Shear Performance and Residual Axial Capacity of Rectangular RC Bridge Piers under Near-Ground Lateral Loads

Reinforced concrete (RC) bridge piers of highway viaducts are exposed to the vehicular impact hazard with impact location usually close to the ground (i.e., bottom of the pier), thus resulting in dominant shear damage. Different simplified approaches for the assessment of RC bridge pier performance under impact loads are generally based on equivalent static models. One crucial element for these approaches is the determination of the static shear performances and residual axial capacity. Because of limited experimental results available under these conditions, six half-scale rectangular RC columns with different volumetric reinforcement ratios and axial compressive loads were tested under near-ground lateral loads with monotonic static conditions. Test results indicate a clear major diagonal crack at the bottom of RC columns with an inclination angle of approximately 30° below the point of application of the lateral load, and it eventually slips along the crack surface under axial loads followed by failure (i.e., loss of residual axial capacity). The increase in the volumetric reinforcement ratio significantly improves the shear deformation capacity and shear crack resistance with a slight increase in the shear capacity. The increase in the axial load can also slightly increase the shear capacity of the columns but is accompanied by a reduction in shear deformation capacity. Additionally, prediction performances of three commonly used shear capacity models for the case of RC columns under near-ground lateral loads are investigated. Finally, based on the test results, an existing residual axial capacity model is modified to improve its prediction performance.