含初始缺陷钢结构损伤累积至断裂及后期的调查分析

DAMAGE ACCUMULATION,FRACTURE AND POST FRACTURE ANALYSES FOR INITIALLY FLAWED STEEL STRUCTURES

为分析钢结构损伤累积至断裂的演变过程,从含初始缺陷钢结构的敏感性出发,提出了基于钢结构动态损伤响应分析的断裂数值模拟理论框架,指出该问题的实质就是求解钢结构在工作应力远低于屈服应力的情况下发生断裂对应于初始缺陷对疲劳寿命增加的百分数。设定初始缺陷为敏感激励参数,并给出疲劳寿命、强度退化以及二者间的数学计算模式。应用确定安全期限的缺陷敏感性理论,运用强度退化方法计算并比较不同初始缺陷情况下钢结构抗断裂韧性和疲劳寿命数值之间的偏差,表明了本法的可行性和有效性。这些结论可为钢结构安全设防提供指导和参考。

The numerical simulation method that is based on the dynamic damage responses of initially flawed steel structures is proposed. It is pointed out that the critical step is to solve the fractures of steel structures with working stresses lower than yield stress. In order to analyze the developing process from damaging to fracturing of steel structures, the sensitivity of the initially flawed steel structure used to predict the damage accumulation is presented. The initial crack is regarded as the sensitivity parameters, and the mathematical models are provided for the fatigue damage of steel structures. Numerical examples are presented to demonstrate the feasibility and effectiveness of the proposed method for the fracture resistance and fatigue life of steel structures with different initial flaws. The conclusions can offer guidelines for the security design of steel structures.