Nonlinear Model Validation And Parameter Calibration Of Bridge Structure Based On Dynamic Responses

The bolts,gaps,boundaries and the damaged structure itself can cause nonlinear behavior in bridges.Nonlinear phenomena are common in bridge structures.With the development of light and flexible structure style,the nonlinear effect becomes more and more important.How to accurately simulate and analyze the nonlinear behavior of bridge structure is of great significance to ensure the safety of structure.This thesis mainly study nonlinear model validation and parameter calibration of bridges based on dynamic responses.The main work is as follows:(1)This thesis studied nonlinear model validation and parameter calibration of single-degree-of-freedom(SDOF)system.The nonlinear type of SDOF system was identified based on restoring force surface and support vector machine.The nonlinear index was calculated by using restoring force surface and used as train data to generate support vector machine.Then the nonlinear type can be identified according to pattern recognition.Once the nonlinear type was known,the function form and unknown parameters can then be determined based on the least squares estimation method.(2)This thesis studied nonlinear model validation and parameter calibration of multiple-degree-of-freedom(MDOF)system.The relationship between restoring force and relative displacement was obtained by dynamic equation.Then the nonlinear type and parameter of stiffness was identified and the parameter of damping was calibrated.This thesis first studied MDOF shear type structure as numerical example by using the proposed method.Then,beam type structures with considering the rotational effect was studied as numerical example.The numerical results demostrated that the proposed method can effectively identified the nonlinear model and calibrated the model parameters for MDOF structure based on the dynamic responses.(3)Finally,a continuous rigid frame bridge was taken as the engineering example to simulate the bridge nonlinear behaviour.The software OpenSees was used to establish the finite element model of the bridge,and the bottoms of the bridge piers were assumed to be nonlinear.Based on the proposed method,the nonlinear system of the bridge was identified.The position and type of nonlinear behavior was effectively identified,and the nonlinear parameters were calibrated with high accuracy.