悬索桥结构基于敏感性分析的动力有限元模型修正

SENSITIVITY-BASED FE MODEL UPDATING OF A SUSPENSION BRIDGE

提出一种悬索桥结构基于特征值敏感性分析的有限元模型修正方法。由结构特征值关于模型参数的灵敏度矩阵建立理论／试验频率差与模型参数摄动之间的关系式。根据待修正参数的不确定性，将参数摄动限制于预设的范围，并将参数修正转化为不等式约束优化问题迭代求解。通过一1／150比例的悬索桥模型的试验分析，验证了这一模型修正方法的可行性。

This paper present an eigenvalue sensitvity-based finite element (FE) model updating approach for suspension bridges.The FE model is updated in an iterative fashion so as to reduce the differences between the analytical and the measured natural frequencies. An eigensitivity matrix is first obtained from the first-order Taylor series expansion of the eigenvalues with repect to some parameters to be adjusted. A set of linear equations relaing the perturbations of parameters to the differences between the analtical and the measured natural frequencies are then established. The parameters to be updated are assumed to be bounded within some prescribed regions arcording to the degrees of uncertainty and variations that etisted in the parameters . The changes of these parameters are found by solving a quadratic matrix equation tha comes from a constrained optimization problem. The current improved model updating methodology is applied on a 1/150 scaled suspension bridge model. The final updated FE model for the suspension bridge model is able to produce natural frequencies in good agreement with the measured ones.