基于有限元可靠度的大跨度悬索桥颤振稳定性评估

Flutter instability assessment on long-span suspension bridges based on finite element reliability

针对已有的大跨度悬索桥颤振及静风稳定性可靠度分析方法中,均存在难以满足工程应用要求的问题,本文将可靠度理论和有限单元法相结合,建立大跨度悬索桥颤振及静风稳定性可靠度分析方法。以西堠门大桥为研究对象,采用基于FORM的有限元可靠度方法计算西堠门大桥的颤振及静风稳定性可靠度指标,分析随机变量均值、随机变量变异系数以及差分步长对西堠门大桥颤振及静风稳定性可靠度指标的影响。研究结果表明,在大跨度悬索桥颤振稳定性可靠度评价中,有必要计入参数随机性的影响,可采用本文提出的方法进行大跨度悬索桥颤振稳定性可靠度评估,参数的随机性对西堠门大桥颤振稳定性可靠度指标有重要影响,忽略参数的随机性有可能导致结构的颤振稳定性偏于不安全。

The existing reliability analysis methods for flutter and aerostatic stability of long-span suspension bridges are difficult to meet the requirements of engineering application.Based on the finite element method and the reliability theory,the approach to reliability analysis of flutter and aerostatic instability of long-span suspension bridges is proposed.The reliability of flutter instability of long-span suspension bridges is estimated by using the proposed method with Xihoumen Bridge as an example.The reliability indexes for flutter instability of Xihoumen Bridge are calculated using the finite element reliability method based on the FORM approach.The influences of mean value and coefficient of variation of random variables,and the iterative step length of finite difference to the reliability index of flutter instability of Xihoumen Bridge are analyzed.The results indicate that it is necessary to consider uncertainties of random variables in reliability assessment on flutter instability of long-span suspension bridges with the proposed method recommended to assess reliability for flutter instability of long-span suspension bridges.The randomness of the parameters has an important influence on the reliability index for the flutter stability of the Xihoumen Bridge.Neglecting the randomness of the parameters might result in the instability of the structure.