考虑应力松弛的张力结构症状可靠度分析

为了确定张力结构因应力松弛而引起的性能退化,用前人实验所得的钢绞线松弛模型代替结构索的松弛过程,建立以构件应力改变量为主要症状的可靠度分析方法.在构件预应力不断改变的条件下,将控制构件的应力改变量随时间的变化曲线用于拟合Weibull模型曲线,以该生命症状模型对索穹顶结构进行基于症状的可靠度分析和结构剩余寿命预测.以计算值代替实际监测值,根据计算值与理论值的差异对可靠度的分析结果进行相应的修正.通过算例表明,在单一损伤应力松弛所致结构性能退化的条件下,结构剩余寿命以年限为基准逐年递减；症状可靠度随症状值的增大而减小,表现出早期呈非线性缓慢下降、后期基本上线性急速下降的特点.

Symptom-based reliability analysis for tensile structure considering stress relaxation

In order to determine the behavior deterioration of tensile structures due to stress relaxation, the symptom-based reliability analysis method with stress variations in the members as main symptom was established. Structural cable’s relaxation process over time was simulated by the relaxation formula of steel strand previously obtained from experiments. With the continuously changing of prestress values in the members, the amounts of stress change in the controlling member over time were employed for fitting of Weibull model curve. The fitted Weibull curve was utilized for symptom-based reliability analysis and remaining lifetime prediction of cable dome structures. The results of reliability analysis were corrected according to the differences between symptom analytical values and measured values which were replaced by calculation values from relaxation formula of steel strand. The results from a case study show that remaining useful lifetime is yearly decreasing with the used years, and the structural symptom reliability is decreasing with increasing values of symptom under the consideration of structural deterioration solely due to stress relaxation. The variation of the structural symptom reliability over the symptom values is featured with the characteristics of slowly decline in nonlinearity at early time and sharply decline basically in linearity at the later time．