Seismic Performance Evaluation of Reinforced Concrete Columns During Fire Exposure

Abstract

Reinforced concrete (RC) structures may suffer fire, earthquake, and other loads during their life cycle. The coupled disasters will lead to further deterioration and damage to structural performance, which has attracted the attention of many researchers. This paper established a series of three-dimensional finite element models of RC columns subjected to simultaneously combined fire and cyclic loads and investigated the seismic performance of the RC column during fire exposure. The models considered mechanical properties degradation of reinforcement steel, concrete, and the nonlinear bond strength‐slip behavior at elevated temperatures. After verifying the numerical model through the skeleton curve and damage character, the hysteretic energy dissipation, ductility, and other seismic parameters of the RC column subjected to simultaneously combined fire and cyclic loads were systematically analyzed. The results show that the severely damaged region of the RC column gradually shifts from the bottom to the middle of the RC column with fire duration increases. The fire duration can improve the yield displacement but reduce the hysteretic energy dissipation and the peak force of the RC column. The ductility of RC columns during fire exposure is smaller than that at room temperature except for the working conditions with a short fire duration and the axial load ratio that is not greater than 0.3. To avoid the excessive seismic performance degradation and buckling failure of the RC column during fire exposure, the recommended limit value of the axial load ratio used in this paper is 0.3.