Seismic performance of steel-reinforced concrete-filled rectangular steel tubes after exposure to non-uniform fire

In actual engineering, non-uniform fire boundary circumstances including single-sided fire, neighboring or related two-sided fire, and three-sided fire, are created due to the varying placements of the columns. In this paper, the seismic performance of SRCFST members subjected to non-uniform fire was investigated by the method of finite element simulation. First of all, the P-Δ curve, ductility coefficient, stiffness, and energy dissipation of the members following non-uniform fire were investigated. As the number of fire surfaces decreases, the maximum overfire temperature at the center of the section decreases, damage decreases, stiffness degradation decreases, and energy dissipation capacity increases. Next, the load distribution of each component in the SRCFST member was calculated using a three-sided fire as an example, the results show that steel tubes play the most dominant role in the seismic performance after fire, followed by steel sections and concrete the least. Last, a parametric study of the key variables influencing the ductility coefficient was carried out.