以沪蓉国道四渡河深切峡谷特大钢桁架悬索桥为工程背景,综合考虑悬索桥结构非线性与重力刚度因素影响,采用ANSYS的APDL语言编写桥梁模型修正优化程序,实现了有限元分析和模型修正的同步计算。通过对比不同的优化算法、不同的目标函数与不同的约束条件对模型修正效果的影响程度,并结合实测吊杆力数据和考虑伸缩缝刚度参数影响,提出了一种全面反映悬索桥结构特性的桥梁有限元模型实用修正方法。采用频率残差目标函数,将频率、振型参数与其他静力信息作为约束条件,进行了模型零阶优化计算。计算结果表明:修正后模型的结构静动力计算响应与实测响应之间的误差明显减小,各测点静力变形误差小于8%,振动频率误差小于5%,并且有限元模型的参数变化合理,保证了参数本身的物理意义,从而利用修正方法获得了四渡河特大桥的基准有限元模型。
Based on the engineering background of the super long-span steel truss suspension bridge over Sidu River Deep-Cutting Gorge on Hu-Rong National Highway,the influences of suspension bridge structural nonlinear and gravity stiffness were comprehensively considered,an updating programme of bridge model was developed by using APDL of ANSYS,and the synchronous calculation on finite element analysis and model updating was realized.The influence degrees of different optimization algorithms,different objective functions and different constraint conditions on model updating effects were compared,the influences of measured suspender forces and expansion joint rigidity parameters were analyzed,and a practical updating method,which could fully reflect the structural properties of suspension bridge,was proposed.In the method,the frequency residual was taken as objective function,the frequency,modal parameters and other static information were taken as constraint conditions,and the zero order optimization was carried out.Calculation result shows that the deviations between the computed and measured responses of structural static and dynamic forces for the updating model decrease significantly,the static deformation errors are controlled within 8%,the frequency errors are controlled within 5%,the parameter variations of the model are reasonable,the physical meanings of the parameters are ensured,so the benchmark finite element model of super large bridge over Sidu River is obtained and feasible.3 tabs,13 figs,13 refs.