一座现有拱桥面内失稳的可靠度随机有限元分析

RELIABILITY STOCHASTIC FINITE ELEMENT ANALYSIS OF IN-PLANE BUCKLING OF AN EXISTING ARCH BRIDGE

用基于一次可靠度方法的可靠度随机有限元对一座现有的钢筋混凝土拱桥面内稳定性进行剩余可靠度计算,并对影响稳定性可靠度的主要参数进行了灵敏度分析。以随机变量和随机场表示现状荷载(汽车荷载、人群荷载、桥面二期恒载和结构自重)及结构参数(主拱圈弹性模量)。用作者提出的基于线性回归的随机场离散方法离散上述随机场,以有限元稳定分析的解作为复杂结构的隐式功能函数。上述功能以及失稳特征值对基本变量的梯度计算均已包含在作者开发的可靠度随机有限元程序RESFEP中。分析给出此桥稳定性可靠度值。灵敏度分析表明:在各随机变量中,拱肋弹性模量随机场离散变量对拱桥可靠度指标影响最大,汽车荷载随机场离散变量次之;在各随机变量的均值和标准差中,拱肋弹性模量随机场离散变量均值和标准差对拱桥可靠度影响最大,汽车荷载随机场离散变量的均值和标准差次之。

Stability reliability of an existing concrete arch bridge is analyzed using the reliability stochastic finite element method. （RSFEM） on the basis of the first order reliability method （FORM）. Dead loads, superimposed dead loads, traffic loads and pedestrian loads and the elastic modulus are represented by random variables or random fields, The random fields are discretized using a linear regression discretization method developed by the authors. The limit state function is implicitly represented by finite element stability analysis results. The above procedures and the determination of the gradient of stability eigen values with respect to basic variables are included in the reliability stochastic finite element computer program RESFEP developed by the authors. The analysis gives reliability value of the arch bridge. Sensitivity analysis shows that the elastic modulus of arch ribs affects the bridge reliability most severely, and traffic load has the next severe influence on the reliability.