基于概率的钢桥焊接构件疲劳养护策略优化方法

摘要

将线弹性断裂力学、结构可靠度理论与全寿命成本分析法相结合,提出基于概率的钢桥焊接构件疲劳养护策略优化分析方法.根据钢桥焊接构件疲劳裂纹的尺寸,采用分级维修策略,根据全寿命思想将养护费用分为检测费用、维修费用和失效费用；基于构件的需检、维修和失效概率,以构件满足最小允许可靠度的养护总费用最小为优化目标,进行养护策略优化分析.对某悬索桥钢箱梁横向加劲肋疲劳养护策略优化分析的结果表明,检测费用对最优检测维修时刻的影响最明显；检测费用增大,最优检测维修时刻推迟；维修费用增大,最优检测维修时刻提前；折现率能改变总费用的值；当失效概率很小时,失效费用增大对最优检测维修时刻影响不大.提出的养护策略优化方法简单实用,可操作性强,可用于类似钢结构的养护优化.%A probability-based optimization method for the fatigue maintenance strategies of steel bridge welded components was presented with the combination of linear elastic fracture mechanics (LEFM), the structure reliability theory and whole life cycle cost analysis method. Classification maintenance strategy was adopted according to the fatigue crack sizes of steel bridge welded components. Maintenance cost was divided into inspection, repair and failure costs according to the whole life cycle cost method. Maintenance strategy optimization was carried through based on the inspection, repair and failure probabilities of components , with the minimum total maintenance cost for the component to satisfy the minimum allowable reliability as optimization objective. Optimization analysis was carried on the fatigue maintenance strategies for the transverse stiffener in the steel box girder of certain suspension bridge. Results show that inspection cost has the most significant influence on the optimal maintenance time. The optimal maintenance time will be delayed by the increase of inspection cost. The optimal maintenance time will be advanced by the increase of repair cost. Discount rate can change the value for total maintenance cost, but when the probability of failure is very small, the increase of failure cost has little effect on the optimal maintenance time. The proposed optimization method for maintenance strategies is simple, practical and maneuverable, which can be applied to similar steel structures for maintenance optimization.