Practical updating method of finite element model for long-span steel truss suspension bridge

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.