腐蚀环境下钢-混凝土组合梁桥疲劳寿命计算

Calculation of the Fatigue Life of Steel-concrete Composite Girder Bridges under Corrosive Environment

随着车重和车流量的增长,我国公路桥梁的疲劳安全问题日益突出。对环境腐蚀下桥梁疲劳问题展开了研究。基于S—N曲线和Miner线性累积损伤理论,考虑了不同疲劳车车重、日均车流量和环境腐蚀的作用,计算了某钢-混凝土组合梁桥的疲劳寿命。定义了疲劳修正系数并提出了用该系数考虑环境腐蚀对桥梁疲劳寿命影响的计算方法。研究结果表明:随着疲劳车车重或日均车流量的增长,腐蚀对疲劳寿命的影响逐渐减小。对于B类疲劳细节,在轻度、中度和重度腐蚀环境下,腐蚀引起疲劳寿命的最大降低比例分别为5%、9%和44%。疲劳修正系数可用于考虑腐蚀影响的组合梁桥的疲劳设计和评估,其取值与疲劳细节类别、环境腐蚀等级和无腐蚀环境下疲劳寿命有关。

With the increase of vehicle weight and traffic volume, the fatigue problem of bridges has become more and more important. Based on the S - N curves and Miner’s fatigue damage theory, the fatigue life of a steel-concrete composite girder bridge was studied in this paper, in which the effects of three important parameters including the fatigue truck weight, average daily truck traffic volume and corrosion were considered. The fatigue correction coefficient was defined and proposed to consider the influence of corrosive environment on the fatigue life of bridges. The research results show that with the increase of fatigue truck weight or the average daily truck traffic volume, the effect of corrosion on the fatigue life is gradually reduced. For Class B details, due to corrosion their fatigue life will decrease by 5%, 9%, and 44%, respectively, under mild,moderate, and severe corrosion environments. Fatigue correction coefficient can be used to consider the effect of corrosion in the design and evaluation of steel-concrete composite girder bridges. The value of the coefficient is related to fatigue detail category, environmental corrosive level, and the fatigue life of the bridge in non-corrosive environment.