Abstract: The collapse process of a RC (reinforced concrete) frame structure is analyzed considering strength and stiffness degradation caused by cumulative damage and strain rate effect. A user subroutine VUMAT that can be applied to the explicit dynamic module of ABAQUS is coded. The comparison between the simulated results and experimental results of a RC column under static and dynamic loading modes proves the reliability of the coded subroutine. Incremental dynamic analysis of a six-story RC frame structure is conducted to study the top displacement, the story drift and base shear of the structure during the seismic collapse process. The analytical results show that the load-bearing capacity of the column is improved when the strain rate effect is considered, but the degradation effect is more obvious. Therefore, the structural analysis under the earthquake should take the rate effect and degradation effect into account. By defining the component damage and layer damage, the numerical simulation can give the weak layer and the failure path, simulate the collapse process of the structure, reveal the collapse mechanism of the structure and provide a reference for the anti-collapse design.