U肋与横隔板焊接构造细节疲劳强度研究

Study of Fatigue Strength of Structural Details of U-Rib and Diaphragm Welding Joints

为研究在车辆荷载反复作用下,正交异性钢桥面板U肋与横隔板焊缝构造细节处的疲劳强度是否满足疲劳设计要求,以九江长江公路大桥钢箱梁结构为研究对象,设计疲劳试样进行疲劳试验,得到了用于该构造细节处疲劳寿命评估的失效概率分别为50%及2.3%的应力幅~循环次数曲线,参照Eurocode 3规范,将疲劳曲线延长至长寿命区,提出适合该细节处的疲劳设计曲线及方程。依据实测车辆荷载谱及简化的有限元模型,选择合理的加载方式与荷载冲击系数,计算得到关注点的应力~时间历程曲线,并评估该构造细节的疲劳寿命。结果表明,在实测荷载谱作用下,该细节处最大应力幅值为24.49MPa,小于疲劳截止限,其疲劳强度满足疲劳设计要求。

To study if the fatigue strength of the structural details of U-rib and diaphragm welding joints of the orthotropic steel bridge deck plates can meet the fatigue design requirements under the action of repeated vehicle load, the steel box girder structure of Jiujiang Changjiang River Highway Bridge was taken the research object, the fatigue samples were designed, the fa- tigue tests were carried out and the stress amplitude^numbers of cycling curves with the failure probability respectively being 50~ and 2.3~ for assessment of the fatigue life of the structural details were obtained. With reference to the Eurcode 3, the obtained fatigue curves were extended to the life zone and the fatigue design curves and equations that were suitable for the structural details were proposed. Based on the measured vehicle load spectrum and the simplified finite element model, the proper loading ways and load impacting coefficients were selected, the stress- time history curves of the concerned points were calculated and the fatigue life of the structural details were assessed. The results of the calculation and assessment show that under the action of the measured vehicle load spectrum, the maximum stress amplitude value of the structural details is 24.49 MPa, the value is less than the fatigue cut-off limit and therefore the fatigue strength of the structural details can meet the fatigue design requirements.