Abstract: A reliability analysis method of the shear capacity of the oblique section and the combined interface of the reinforced concrete composite beams after high temperature is provided. Firstly, the thermal parameters of reinforced concrete (RC) beams were selected, and the heat conduction analysis was performed using ABAQUS. Based on the thermal analysis results and the calculation method of the shear capacity of RC composite beams after high temperature, the residual bearing capacity of the oblique section and the combined interface after fire was obtained. Finally, based on MATLAB, Monte Carlo method was used to analyze the reliability. The results show that the heating duration has a significant effect on the reliability. The reliability index increases with the increase of the concrete strength and the stirrup reinforcement ratio. It increases first and then changes little with the increase of the load ratio. The reliability of the oblique section bearing capacity of RC composite beams is greater than that of the combined interface at room temperature, but with the increase of heating time, the shear strength of combined interface is better than that of the oblique section. This method can be applied to the reliability analysis of the bearing capacity of RC composite beams after high temperature, and has high precision and accuracy.

Key words: fire, reinforced concrete composite beams, oblique section, combined interface, high temperature, reliability, Monte Carlo Method