基于断裂力学理论拉索疲劳寿命定量分析方法研究

Research on quantitative analysis method of cable fatigue life based on fracture mechanics theory

基于金属疲劳断裂理论,给出了拉索类桥梁拉索疲劳强度的定量分析方法,通过对计算式的分析可以得到如下结论:应力疲劳寿命分析方法能够考虑拉索截面尺寸、材料塑性以及外界荷载产生应力比等因素对拉索疲劳寿命的影响,分析理论正确,考虑的因素比较全面,是进行拉索疲劳寿命分析的较好方法。同时,拉索类桥梁索体的疲劳强度的设计,应该采用当量名义应力幅表示的理论疲劳极限作为拉索的疲劳强度设计值,当量名义应力幅表示的理论疲劳极限考虑了外界荷载产生的应力比对拉索疲劳寿命的影响,与传统的疲劳强度估算方法相比,具有充分的理论依据,考虑因素更加全面,结果更加可靠。

Based on the metal fatigue fracture theory,the quantitative analysis method of the cable fatigue strength of cable-type bridges was given.The analysis of the calculation formula can be concluded as follows:the stress fatigue life analysis method can consider the influence of such factors as the cable section size,material plasticity and stress ratio produced by external load on the fatigue life of the cable.The analysis theory is correct and the factors considered are comprehensive.It is a better method to analyze the fatigue life of the cable.At the same time,the fatigue strength design of the cable-stayed cable body should be based on the theoretical fatigue limit expressed by the equivalent nominal stress amplitude as the fatigue strength design value of the cable.The theoretical fatigue limit expressed by the equivalent nominal stress amplitude takes into account the effect on cable fatigue life of stress ratio generated by the external load.Compared with the traditional fatigue strength estimation method,this method has a sufficient theoretical basis,and the factors considered is more comprehensive,and the result is more reliable.