基于径向基函数响应面方法的大跨度斜拉桥有限元模型修正

摘要

采用ANSYS有限元软件建立某大跨度斜拉桥试验室物理模型的三维有限元模型.基于灵敏度分析,选取模型待修正参数和用于模型修正的特征量.采用实验设计方法生成数样本,通过有限元分析提取对应的特征量信息,进而建立待修正参数与特征量关系的径向基函数响应面模型.通过对响应面模型的拟合误差分析,确定径向基函数的最优形状参数.以斜拉桥自振频率和静态索力构建目标函数.基于建立的响应面模型,采用遗传优化算法进行有限元模型修正.结果表明,采用径向基函数响应面模型拟合斜拉桥设计参数与特征量之间的隐式关系有较高的精度；基于仿真数据的模型修正有较高的精度,基于试验数据的模型修正能得到合理的结果,该方法可有效地修正复杂桥梁结构有限元模型.%A three-dimensional finite element (FE) model of a scale long-span cable-stayed bridge model was built by ANSYS software, and sensitivity analysis was carried out to select design parameters and characteristic quantities for model updating. The samples of design parameters were generated by experimental design method, and the corresponding characteristic quantities were extracted based on FE analysis. Then, response surface models (RSM) based on radial basis function (RBF) were constructed to approximate the relationship between design parameters and characteristic quantities. The optimal shape parameters for RBF were determined by investigating the approximation error of RSM. With the natural frequency and static cable force of cable-stayed bridge, the objective function was constructed. Based on the established RSM, FE model updating was performed by genetic optimization algorithms. The results indicate that RSM of RBF has a higher precision for approximating the implicit relationship between design parameters and characteristic quantities of cable-stayed bridge. Simulated analysis shows that the updated results are of higher accuracy, and the model updating based on experimental data indicates that the results are reasonable. It is demonstrated that the proposed approach is valid for FE model updating of complicated bridge structures.