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由于循环外荷载和腐蚀性环境的共同作用,近海桥梁结构易受疲劳破坏.本文提出了一种考虑钢材锈蚀的桥梁结构改进疲劳可靠度评估模型,并基于青马大桥长期结构健康监测数据对其典型焊接节点的概率疲劳寿命进行了评估.通过建立有效截面衰减模型和材料疲劳性能退化函数,利用Miner损伤累积准则的连续概率函数表达式,提出了考虑钢材锈蚀的疲劳可靠度解析模型.同时考虑交通载荷(包括汽车载荷和火车载荷)和台风影响,通过统计分析长期应变监测数据建立了标准日应力谱.采用有限混合分布方法及基于遗传算法的混合参数估计算法,得到了标准日应力谱多模态有限混合分布函数.比较分析了考虑和未考虑钢材锈蚀的焊接节点疲劳寿命失效概率和可靠度指标,研究结果表明钢材锈蚀因素对桥梁焊接节点的疲劳可靠度评估结果有较大影响.
Due to the combination of cyclic load and corrosive environment, the offshore bridge structure is vulnerable to fatigue damage.This paper presents an improved fatigue reliability assessment model of bridge structure considering the steel corrosion, and based on the long-term structural health monitoring data of Tsing Ma Bridge The probability fatigue life of a typical welded joint was evaluated.A fatigue life prediction model based on continuous probability function expression of Miner damage cumulative criterion was established by establishing an effective section attenuation model and material fatigue performance degradation function Traffic load (including vehicle load and train load) and typhoon influence, the standard daily stress spectrum was established by statistical analysis of long-term strain monitoring data.Using the finite mixture distribution method and the genetic algorithm based hybrid parameter estimation algorithm, Modal finite mixed distribution function.The failure probability and reliability index of fatigue life of welded joint considering or not considering steel corrosion are comparatively analyzed.The results show that the corrosion factor of steel has a great influence on the fatigue reliability assessment of bridge welded joint.