Fire Response Analysis of Prefabricated Combined Reinforced Concrete Beams Based on Finite Element Model Correction

To obtain an accurate finite element model (FEM) for response analysis of prefabricated combined reinforced concrete beam (PCRCB) under fire exposure, a stepwise FEM correction method is proposed based on the improved response surface method. Four T-shaped PCRCBs were designed and cast to verify the accuracy and practicality of the proposed method. Firstly, based on the static and dynamic tests before fire exposure, the FEM was corrected using the proposed correction strategy. The proposed method is initially validated by comparing the modal responses. Subsequently, a fire test was carried out. The test phenomena, temperature field, mid-span deflection and dynamic response under fire were analyzed. Finally, considering the development of crack, the static and dynamic responses under fire exposure were further simulated based on the modified FEM. The results indicate that the established FEM can accurately simulate the structural response. The spanwise deflection and fundamental frequency exhibited nonlinear variations with fire exposure time, which were strongly influenced by the load ratio. The proposed model correction method establishes the basis for the detail response analysis of PCRCB during fire exposure.