Safety Evaluation Of Reinforced Box Arch Bridge Based On Static And Dynamic Finite Element Model Updating

There are a large number of bridges in service in China,and the daily maintenance task is arduous.The bridge management department needs to carry out safety assessment quickly and accurately,make reinforcement decisions and formulate the optimal maintenance and reinforcement scheme.In order to reasonably evaluate the bridge safety,based on the field measured data,the finite element model is modified,and the fuzzy comprehensive analytic hierarchy process is applied to evaluate the bridge safety.Using this method,the following research work is carried out around a reinforced concrete box arch bridge(1)The appearance inspection of a reinforced concrete box arch bridge,such as material condition,geometric alignment,component damage and so on,was carried out,and the static and dynamic load test was carried out.The response data of the bridge under static and dynamic loads were obtained,and the overall stress condition of the bridge structure was preliminarily judged.The load test results show that after two times of reinforcement,the stiffness of the bridge is high and the calibration coefficient is low.According to the old bridge drawings,reinforcement design scheme and disease conditions,the initial finite element model is established.(2)Through sensitivity analysis,the elastic modulus of the main arch ring,bending moment of inertia,unit weight,vertical wall unit weight,bridge deck thickness and translational stiffness and rotational stiffness at the arch foot of the main arch ring are selected as the parameters to be corrected,and the objective function of displacement and frequency difference is constructed.The NSGA-Ⅱ algorithm is used to solve the multi-objective optimization problem,and the parameters of the initial finite element model are modified.The calculation results show that the modified model can better reflect the actual working condition of the bridge.(3)Using the modified finite element model to calculate the bearing capacity,deformation and other indicators,and based on the fuzzy comprehensive analytic hierarchy process theory,a safety evaluation model for reinforced concrete box arch bridge is established.The expert scoring method is used to establish the judgment matrix with the index scale,calculate the weight of each underlying index,and quantify the fuzzy evaluation index.The method is applied to the actual bridge to verify its applicability and effectiveness.