Combined Static And Dynamic Model Updating Of Bridge Based On Linear Weighting-sum Selection Method

Bridge structure is affected by environmental erosion and other adverse factors,so the overall safety will gradually decrease.In order to ensure its safe operation,some important bridges are usually regularly tested for structural safety,damage diagnosis and performance evaluation.They often need to build finite element model of the structure to assist in the analysis and evaluation.Because the initial finite element model based on the original design data will be affected by various errors,it can not accurately reflect the real state of the structure.Therefore,it is necessary to updating the initial finite element model based on the measured static and dynamic responses and characteristics of the structure.Relying on the support of Jilin Provincial Science and Technology Development Program(20180201083SF),the following research works have been done:1)Aiming at the problem of selecting the optimal coordinated solution on the Pareto front for multi-objective optimization,the linear weighting-sum selection method is proposed to select the optimal coordinated solution.Compared with the traditional method,it is also suitable for the selection of the optimal coordinated solution for multi-objective optimization with three objectives or more higher dimensions.2)Aiming at the complex multi-objective optimization problem of finite element model updating of large bridge structures,a combined static and dynamic model updating of bridge based on linear weighting-sum selection method was proposed.It first solve Pareto optimal solution set of the multi-objective optimization problem using the non dominated sorting genetic algorithmⅡ,then select the coordinately optimal solution of the Pareto optimal solution set using linear weighting-sum method to complete model updating.The excellent global multi-objective search ability of NSGA-Ⅱis combined with the efficient solution selection ability of linear weighting-sum method.It not only avoids the difficulty of solving the complex multi-objective optimization problem directly with the linear weighting-sum method,but also solves the problem of selecting the coordinately optimal solution of Pareto front in the multi-objective optimization problem.The randomness and fluctuation of some traditional methods are avoided effectively,and the optimization efficiency of the whole model updating process is improved.3)In order to make a quantitative analysis of the finite element model updating effect of bridge structure,a new evaluation mechanism for the model updating result is proposed.The errors of the static and dynamic responses and characteristics in the model updating results of the bridge structure can be evaluated individually and synthetically by using the overall error mean(δ)and combined static and dynamic overall error mean(δ_C),which is conducive to the quantitative evaluation of the model updating effect of the actual structure,and is more convincing.4)The method of this paper is used to the finite element model updating and evaluation of a steel truss bridge,and a good updating effect is obtained.At the same time,the effectiveness of parameter sensitivity analysis and screening in the process of model updating to reduce the complexity of model updating is verified.5)The method of this paper is applied to the finite element model updating and evaluation of a prestressed concrete cable-stayed bridge and a special-shape concrete filled steel tube arch bridge,and the overall static and dynamic updating effect of the structure is good.Comparing with static model updating method and dynamic model updating method,the updating results of the method of this paper take into account both static updating and dynamic updating two optimization objectives,and to make a updating effect of minor loss expense for another optimization target updating effect significantly increased.Therefore,the combined static and dynamic overall error mean(δ_C)is smaller,the coordination between the static and dynamic targets is better,the optimization rate is higher,and the overall updating effect of the structure is better,which can provide a reference for the finite element model updating and evaluation of related bridge structures.