考虑多因素共同作用的钢桥焊接节点疲劳可靠度评估  

Fatigue reliability assessment of welded joints in steel bridges considering multiple effects

作　　者：叶肖伟[1,2] 傅大宝[2,3] 倪一清[2] 黄启远 姜绍飞[3] 

机构地区：[1]浙江大学,浙江杭州310058 [2]香港理工大学深圳研究院,广东深圳518057 [3]福州大学,福建福州350108 [4]香港特别行政区政府路政署

出　　处：《土木工程学报》2013年第10期89-99,共11页China Civil Engineering Journal

基　　金：中央高校基本科研业务费专项资金(2013QNA4023)

摘　　要：提出考虑多因素共同作用的钢桥焊接节点疲劳可靠度评估方法,该方法不仅考虑焊接节点的应力集中效应,同时也考虑钢材锈蚀引起的焊接节点有效截面积衰减和疲劳性能退化。基于该方法,采用长期应变监测数据评估青马大桥典型焊接节点的疲劳可靠度。通过研究焊接节点热点应力幅随机特性、钢材锈蚀引起的有效截面积衰减模型及疲劳性能退化函数,利用疲劳损伤累积Miner准则连续函数概率解析表达式,建立考虑多因素共同作用的疲劳可靠度模型。综合考虑交通荷载(包括汽车荷载和火车荷载)和台风影响,通过统计分析长期应变监测数据建立标准日应力谱。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,获得标准日应力谱多模态有限混合分布函数。比较分析应力集中效应和钢材锈蚀因素(包括有效截面积衰减和疲劳性能退化)对焊接节点的疲劳寿命失效概率和可靠度指标的影响规律。结果表明,应力集中效应和钢材锈蚀因素对焊接节点的疲劳可靠度评估结果有较大影响。A novel method for fatigue multiple effects in terms of the stress effective cross-sectional area and the d reliability assessment of welded joints in steel bridges is proposed by considering concentration phenomenon at the welded joint as well as the reduction of the egradation of the fatigue behavior due to steel corrosion. The proposed method is applied to assess the fatigue reliability of a typical welded joint in the instrumented Tsing Ma Bridge using the long-term strain monitoring data. By exploring the stochastic characteristics of the hot spot stress range, the reduction model of the cross-sectional area, and the fatigue behavior degradation function of the welded joint, a fatigue reliability model considering multiple effects is developed in the framework of a continuous probabilistic formulation of Miner＇ s damage cumulative rule. A standard daily stress spectrum accounting for highway traffic, railway traffic, and typhoon effects is derived by statistically analyzing the long-term strain monitoring data. A multi-modal Probability Density Function （PDF） of the standard daily stress spectrum is obtained by use of the method of finite mixture distributions in conjunction with a Genetic Algorithm-based （GA-based） mixture parameter estimation approach. A comparative study is conducted to investigate the effects of stress concentration and steel corrosion （ i. e. , reduction of the effective cross-sectional area and degradation of the fatigue behavior） on the failure probability and reliability index versus the predicted fatigue life of the welded joint. The results show that the fatigue reliability of the welded joint is significantly influenced by the effects of stress concentration and steel corrosion.

关 键 词：桥梁健康监测 钢桥 疲劳可靠度 应力集中效应 钢材锈蚀 

分 类 号：U441.4[建筑科学—桥梁与隧道工程]