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涡激共振是大跨度桥梁在低风速下容易发生的一种风致振动,涉及的不确定因素众多,利用可靠度理论对这类风致振动进行安全估算是大跨度桥梁风振研究的趋势。探讨了桥梁涡振的三种失效模式,包括基于涡振风速的失效模式、基于涡振振幅的失效模式和基于前两种失效模式交集的涡振刚度失效模式,基于此,以某座大跨度桥梁为例,应用二次四阶矩法计算了基于涡振振幅的失效概率,并与二次二阶矩法的计算结果进行了比较,用Monte Carlo模拟法(MC)进行了验证,发现基于二次四阶矩法的可靠度分析相对于二次二阶矩法具有较高的精度。然后,基于二次四阶矩法的计算结果得到了桥梁涡振刚度失效的概率,研究表明:单独考虑桥梁涡振发生风速或涡振振幅的失效概率偏于保守,应结合起来考虑。
Vortex-induced vibration is a kind of wind-induced vibration which is prone to occur in long-span bridges at low wind speeds, and many uncertainties are involved. The reliability estimation of such wind-induced vibration using reliability theory is the trend of research on wind-induced vibration of long-span bridges. Three failure modes of bridge vortex vibration are discussed, including failure mode based on vortex-induced wind speed, failure mode based on amplitude of vortex-induced vibration and failure mode of vortex-induced vibration based on the intersection of the first two failure modes. Based on this, Bridge as an example, the failure probability based on amplitude of vortex vibration is calculated by quadratic moment method and compared with the result of second-order moment method. The results of Monte Carlo simulation (MC) The quadratic moments method has higher accuracy than quadratic second moments method. Then, the probability of failure of the vortex-induced stiffness of the bridge is obtained based on the quadratic quadratic moment method. The results show that the failure probabilities of the vortex-induced vibration or the amplitude of the vortex are considered to be conservative, and should be considered together.