Mechanism of shear strength degradation of a reinforced concrete column subjected to cyclic loading

摘要

The purpose of this study was to investigate the mechanism of shear strength degradation of a reinforced concrete (RC) member under cyclic loading. First, the shear failure after flexural yield of tension reinforcing bars of a RC column designed as bridge pier under cyclic loading was simulated by the method of three-dimensional rigid-body-spring-model (3D RBSM) and the shear strength degradation was quantitatively evaluated by a numerical approach. Afterward, based on the shear resistant mechanism, the degraded shear strengths after each load cycle were decoupled into the contributions provided by beam action and arch action, with the use of the numerical local stress results. As the important finding, the mechanism of shear strength degradation due to cyclic loading of the RC column was concluded as with the increase of deformation level, the arch action first degraded gradually whereas the beam action maintained its original capacity; then after losing most capacity of the arch action, the beam action began to decrease rapidly, which caused the shear failure.