恒荷载效应显著结构失效模式分析的弹性模量缩减法

恒荷载效应在土木、水利等大型工程结构的分析中往往占有不可忽略的显著位置。针对传统弹塑性方法分析恒荷载效应显著结构失效模式存在的失效路径依赖性问题，结合截面强度融合技术和弹性模量调整策略，提出恒荷载效应显著结构失效元和失效模式的识别方法，进而建立恒荷载效应显著结构损伤演化和失效模式分析的弹性模量缩减法。首先将恒荷载效应融入构件的截面强度，建立强度和外荷载分布都发生改变的修正结构计算模型；然后根据齐次化广义屈服函数定义单元承载比和基准承载比，建立高承载单元识别的自适应准则；进而通过缩减高承载单元的弹性模量来模拟结构的刚度损伤，并确定结构的极限承载力；最后根据结构进入塑性极限状态时高承载单元的弹性模量缩减幅度批量标示失效元，据此确定结构的失效模式。通过算例分析，验证了该方法具有较强的稳定收敛性，能够取得较高的计算精度和效率，可以更加合理地描述结构的损伤演化过程，具有较强的适用性。

Elastic modulus reduction method for analysis of failure mode of structures with significant dead load effect

The dead load effect often plays an important role in the large-scale civil and hydraulic structures. To analyze the failure mode of structures with significant dead load effect, the traditional elasto-plastic methods have the failure path-dependent problem. To overcome the limitations of the traditional methods, a method of identifying the failure element and the failure mode is proposed by combining the strength incorporation technique with the strategy of elastic modulus adjustment, and then an elastic modulus reduction method is developed for analyzing the damage evolution and failure mode of engineering structures with significant dead load effect. Firstly, a modified computational model with updated strength and external load distribution is established by incorporating the dead load effect into the sectional strength of structural member. Next, based on the element bearing ratio (EBR) and the reference EBR defined by the homogeneous generalized yield function, a self-adaptive criterion of identifying the highly stressed elements (HSEs) is presented. Furthermore, by means of reducing the elastic modulus of HSEs, the structural stiffness damage is simulated, and the bearing capacity of the structure is determined. Finally, the potential failure elements can be identified and marked in terms of the reduction amplitude of elastic modulus of HSEs during the plastic limit state of structure, so that the failure mode can be determined. Based on two numerical examples, the good stability and convergence, high accuracy and efficiency of the proposed method can be validated. Since the proposed method can reasonably simulate the damage evolution of structure, it deserves wide applications.