考虑累积损伤退化及应变率效应的钢筋混凝土框架结构倒塌分析

该文研究考虑累积损伤导致强度和刚度退化及应变率效应的钢筋混凝土框架结构倒塌过程，基于有限元软件ABAQUS平台，开发了相应的显式分析梁单元用户材料子程序，并对钢筋混凝土柱的动态和静态加载试验进行模拟，对比验证了所开发程序的准确性。采用增量动力时程分析法，研究了多维地震输入下某六层框架结构的倒塌过程，对结构的顶点位移、层间位移、基底剪力进行分析。研究结果表明：考虑应变率效应，构件的承载力有一定的提高，但同时退化效应更加显著，因此地震作用下的结构分析应予以考虑率效应及退化效应；通过定义构件损伤和层损伤，可以明显确定结构的薄弱层及破坏路径，模拟在地震作用下的结构倒塌过程，并揭示结构的倒塌机理，对抗倒塌分析提供一定参考。

SEISMIC-COLLAPSE ANALYSIS OF REINFORCED CONCRETE FRAME STRUCTURE CONSIDERING CUMULATIVE DAMAGE AND STRAIN RATE EFFECT

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.