基于初始损伤模型的钢管混凝土组合框架抗连续倒塌分析

Progressive collapse analysis on composite frame with concrete-filled steel tubular columns based on initial damage models

对结构进行整体抗连续性倒塌性能研究,首先要确定结构在外部荷载作用下可能发生的最不利初始损伤模型,即结构体系中某一构件或者子结构在外荷载作用失效后最有可能引起整个结构体系发生连续性倒塌破坏。基于构件失效前后结构应变能的改变量和构件失效影响面积的大小,通过计算构件重要性系数确定了结构的最不利初始损伤模型。在此基础上,以ABAQUS有限元分析软件为求解平台,采用非线性纤维梁-柱单元对一8层钢管混凝土空间框架结构进行连续性倒塌分析。结果表明:钢管混凝土框架柱构件的重要性系数明显大于梁构件,底层中柱构件重要性系数最大,通常认为比较关键的角柱构件并没有出现在关键地位;通过对3种典型初始损伤模型下钢管混凝土框架连续性倒塌分析发现,关键构件失效后,框架梁柱发生内力重分布,而且卸载传力路径遵循就近原则。

To investigate the progressive collapse resistance of structures,the most possible initial damage model should be predicted,i.e.the damage of a member will lead to the progressive collapse of the whole structures.By considering the structural strain energy variation and the influencing areas of localized damage before and after a structural member is damaged,a method was developed to calculate the importance indices of members,which can be used to determine the most possible unfavorable initial damage model of structure.This paper presents a finite element(FE) model of an 8-story spatial frame with concrete-filled steel tubular(CFST) columns based on nonlinear fiber beam-column element theory to study the progressive collapse resistance under different initial damage models using ABAQUS software.The results show that the importance indices of CFST columns are larger than the steel beams'.The importance indices of middle column is the largest and the importance indices of corner column does not appear in the key position.The internal forces of columns and beams will be redistributed since the failure of key column and the unloading-path follows the nearest path principle under three typical initial damage models.