Numerical analysis of axial compressive behavior of RC short columns subjected to non-uniform fire: A meso-scale study

Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education, Beijing University of Technology, Beijing, 100 Pingleyuan, Chaoyang District, China

^* Corresponding author Email: jinliu@bjut.edu.cn

Abstract

The bearing capacity and durability of reinforced concrete (RC) structures can be affected by fire. In this study, a three-dimensional (3D) meso-scale simulation model for RC short column subjected to axial compression after exposure to fire was established. The degradation effect of mechanical properties of steel bars and concrete materials after high temperature was taken into account. The bond-slip behavior between longitudinal steel bars and concrete was also considered in the model. Based on the present simulation method, the failure mode and failure mechanism of the RC short columns were investigated. Moreover, the effects of fire scenario and fire duration on the axial compression performance of RC short columns were further investigated. It is found that the meso-scale numerical model can effectively simulate the mechanical behavior of RC short columns under axial load. Moreover, with the increase of fired surfaces and fire duration, the peak bearing capacity, axial compression stiffness and ductility decrease. The mechanical properties of short columns decrease more quickly under non-uniform fire. By comparing the theoretical value with the numerical simulation value of N_ut/N_u, it is found that the theoretical value is conservative.