风、列车作用下斜拉桥索-梁相关振动对拉索疲劳可靠性的影响

以实际大跨度斜拉桥为研究对象,研究了随机风、列车作用下发生的索-梁相关振动对拉索疲劳可靠性的影响。使用编制的动力有限元计算程序,建立了大跨度铁路斜拉桥全桥3维精细有限元模型,计算了斜拉桥全桥在风、列车动力作用下的振动响应,分析了全桥索-梁相关振动的特性。建立了列车交通荷载概率模型,根据桥位处风速统计数据资料建立了桥梁的风荷载概率模型,对拉索的应力谱进行了计算。依据损伤理论,使用Monte-Carlo方法开展了拉索在风、列车动力作用下的疲劳可靠度分析。研究结果表明:在斜拉桥日常运营状态中,风、列车作用下索-梁相关振动不会导致拉索共振,索-梁相关振动是拉索疲劳可靠性下降的主要原因;对于拉索在长期动力荷载下的疲劳失效概率,风场作用占比很小,列车作用占比较大;各个拉索的成桥状态索力影响了列车作用下的拉索应力幅,进一步影响了斜拉桥在长期动力作用下拉索的疲劳可靠性。

Effects of cable-beam related vibration on cable fatigue reliability of cable stayed bridge under wind and train action

Taking a real cable-stayed bridge as the study object,effects of cable-beam related vibration on cable fatigue reliability of the bridge under wind and train action were analyzed.A 3-D precision finite element(FEM)model of a long span railway cable-stayed bridge was established by using the existing finite element dynamic analysis program,vibration responses of the full bridge under wind and train action were calculated,and characteristics of cable-beam related vibration of the full bridge were analyzed.The probability model of train traffic load was established,and the wind load probability model of the bridge was established according to wind speed statistical data at the bridge position,and the stress spectrum of the cable was calculated.Based on the damage theory,the fatigue reliability analysis of cable under wind and train dynamic action was performed by using Monte Carlo method.The results showed that in daily operation state of the bridge,cable-beam related vibration under action of wind and train can’t cause cable resonance,and cable-beam related vibration is the main reason for the decline of cable fatigue reliability;for the fatigue failure probability of cable under long-term dynamic load,wind field action accounts for a smaller proportion,while train action takes a larger proportion;cable force of each cable in finished state affects cable stress amplitude under train action,and further affects cable fatigue reliability of the bridge under long-term dynamic action.