基于响应面法的非对称钢桁斜拉桥参数敏感性分析

Sensitivity Analysis of Asymmetric Steel Truss Cable⁃stayed Bridge Based on Response Surface Method

非对称钢桁斜拉桥受力和变形具有不对称性,其参数敏感性与对称钢桁斜拉桥有所差异。为了研究各参数对大跨度非对称钢桁斜拉桥结构响应的影响程度,本文采用响应面法构建结构响应与各个参数之间的显式关系式,利用梯度算法求解各参数对某一响应量的敏感度及敏感百分比。采用MIDAS/Civil建立全桥有限元模型,考虑整体升降温、板-桁温差、索-梁温差、低塔刚度、高塔刚度、拉索弹性模量及主梁重量7个参数,分别以中跨跨中挠度、主梁最大弯矩、主梁最大轴力、桥塔根部弯矩及塔顶纵向偏位为结构响应,研究各参数对非对称钢桁斜拉桥结构响应的影响程度。结果表明:主梁重量对结构各个响应的影响程度始终处于最高或者次高位,而其余设计参数对不同结构响应的影响程度均表现出较大差异。同一设计参数对不同结构响应的影响程度不同,应根据需要关注的结构响应控制主要影响参数。

The stress and deformation of asymmetric steel truss cable-stayed bridges are asymmetrical,and their parameter sensitivity is different from that of symmetrical steel truss cable-stayed bridges.In order to study the influence of each parameter on the structural response of a long-span asymmetric steel truss cable-stayed bridge,the response surface method was used to construct an explicit relationship between the structural response and each parameter,and the gradient algorithm was used to solve the sensitivity and sensitivity percentage of each parameter to a certain response quantity.A finite element model of the entire bridge was established using MIDAS/Civil software,taking into account seven parameters,including that overall temperature rise and fall,plate-truss temperature difference,cable-girder temperature difference,low tower stiffness,high tower stiffness,cable elastic modulus and main girder weight.Taking the mid-span deflection,maximum bending moment of the main girder,maximum axial force of the main girder,bending moment at the root of the bridge tower,and longitudinal deviation of the tower top as structural responses,the influence of various parameters on the structural response of asymmetric steel truss cable-stayed bridges was studied.The results show that the influence degree of the main girder weight on the various responses of the structure is always at the highest or second highest level,while the influence degrees of other design parameters on different structural responses show great differences.Therefore,the degree of influence of the same design parameter on different structural responses is inconsistent,and the main influencing parameters should be controlled according to the structural response that needs attention.