考虑区间不确定性的钢结构疲劳寿命分析

Fatigue life prediction of steel structure considering interval uncertainty

针对传统的钢结构疲劳寿命预测误差较大的问题,判别线性累积损伤模型和裂纹扩展模型中变量不确定性和随机性,基于区间-概率理论推导区间模型和含有对数正态分布的概率模型的一致性关系,给出可同时考虑区间变量和随机变量的区间-概率可靠度分析模型和求解方法。实桥中典型疲劳细节验证表明,在模型中变量应力幅的变异系数为0.25-0.35时,本文方法比传统概率算法更为保守,可作为预测钢结构疲劳寿命的一种有效手段。

To reduce the fatigue life prediction error of steel structure using traditional fatigue prediction algorithm,the interval-probability reliability analysis method was presented to deal the fatigue life prediction of steel structure with the consideration of variables uncertainty. The parameters of the linear accumulative damage model and the crack propagation model were distinguished as probabilistic variables and interval variables based on previous studies. The theoretical foundation was established by the consistency relationship between the interval reliability and the probability reliability model with lognormal distributed variables in theory.The solving process was combined with definition of interval reliability index and the probabilistic algorithm.The results of typical fatigue details of actual bridge show that,when the variable coefficient of the stress amplitude is in the range from 0.25 to 0.35,the results of the interval-probability analysis are more conservative than that of traditional probability method.