正交异性钢桥面板焊缝的疲劳寿命评估方法

EVALUATION OF THE APPROACHES FOR FATIGUE LIFE PREDICTION OF WELDED JOINTS OF ORTHOTROPIC STEEL DECKS AND SOME SUGGESTIONS

评述了正交异性钢桥的桥面板焊缝疲劳寿命的评估方法,重点是基于有限元分析和断裂力学的损伤容限法.根据正交异性钢桥的纵肋与桥面板焊缝处循环应力的特点,指出了循环应力比在正交异性桥焊缝的疲劳寿命预测中有重要意义.并首次指出,现在研究者所采用的Paris公式完全不能合理地计算正交异性桥面板焊缝的疲劳裂纹扩展,而必须使用一个以混合型裂纹的应力强度因子幅为控制参数和能考虑以压应力为主的循环应力的疲劳裂纹扩展模型.

The commonly used approaches for the fatigue life prediction of welded joints oforthotropic steel decks are evaluated in this paper,in particular the finite element analysis-based fracture mechanics method.Based on the characteristic of the cyclic stresses at the rib-to-deck joint,it is pointed out in this paper that the cyclic stress ratio has to be taken into account in the fatigue life evaluation of the welded joints of rib-to-deck joints.Furthermore,it is pointed out for the first time that the Paris Law,which has been used in the fracture mechanics based fatigue analysis of orthotropic steel decks by many researchers,is not aproper fatigue crack growth model to predict the fatigue life of the welded joints of orthotropic steel decks.Instead,a fatigue crack growth model which can account for both the stress intensity factor ranges of mixed-mode cracks and the stress ratios in which the cyclic stresses are dominated by the compressive stresses should be employed.