Research On Optimal Placement Of Bridge Health Monitoring Sensors And Damage Identification Method

With the advancement of modern engineering technology,many large and complex structures have emerged in the field of industrial equipment and long-span bridge construction.However,external factors such as long-term vehicle loads,earthquakes,wind loads,and the aging and corrosion of building materials can cause breakage and serious damage to large buildings,and may even lead to collapse accidents.Therefore,how to realize the comprehensive monitoring of the bridge structure with the least number of sensors arranged on the bridge structure has important practical significance.This paper proposes a sensor optimization arrangement method based on Adaptive Whale Optimization Algorithm（AWOA）.And through the bridge health monitoring sensor,the dynamic response information of the bridge structure is obtained in real time,and whether the bridge is damaged is analyzed.If damage occurs,the location of the damage is located,and the real-time evaluation of the bridge’s operation status and health status is realized.This paper takes the cable-stayed bridge of Binzhou Yellow River Highway as an example,establishes its finite element model for dynamic analysis,and then optimizes the number and position of sensors based on the dynamic information of the structure,and sets different degrees of the damage identification method of the bridge structure is studied in the damage case.The main work of this paper is as follows:（1）Through the study of sensor optimization placement method and damage identification method,this paper relies on the Binzhou Yellow River Highway Cable-Stayed Bridge to establish the finite element scale model of the Binzhou Yellow River Highway Cable-Stayed Bridge,and then prestresses the Binzhou River finite element model.state analysis.In order to reduce the redundancy of the input modal parameters and ensure the superiority of the initial data of the optimal placement of the health monitoring sensors as much as possible,this paper uses the Fisher information matrix method and the effective modal mass participation coefficient method to select and calculate the modal order.The combination of methods not only improves the calculation efficiency of the algorithm,but also improves the stability of the algorithm to obtain the optimal solution,and also reduces the redundant information of the structural health assessment system.（2）For Whale Optimization Algorithm（WOA）,there are shortcomings such as insufficient development capabilities,easy to fall into local optimum,and poor robustness.This paper proposes an Adaptive Whale Optimization Algorithm（AWOA）.By decomposing the parameter A in the whale algorithm into a decision factor A₁ and an attenuation factor A₂,A₁balances the global development ability of the whale algorithm to avoid the algorithm falling into local optimization.A₂ dynamically adjusts the search step size of the algorithm to improve the search accuracy of the algorithm.At the same time,Kent mapping is introduced to improve the ergodicity of the initial population distribution of the algorithm.Finally,AWOA is tested through multiple unimodal test functions and multimodal test functions.The results show that the optimization accuracy and robustness of the AWOA algorithm have been significantly improved.（3）Import the extracted input modality of the Binzhou River cable-stayed bridge into the AWOA algorithm,and carry out integer coding on the sensor points to be measured of the cable-stayed bridge,combined with the Modal Assurance Criteria（MAC）for the cable-stayed bridge The optimal arrangement of sensors,so that the AWOA algorithm can solve the problem of optimal arrangement of sensors.Taking the minimum value of the maximum off-diagonal element of the MAC matrix as the objective function,using MATLAB analysis,the optimal value of the objective function value when the number of sensors is the least is obtained,and finally the sensor arrangement scheme is determined.Comparing the sensor placement scheme of AWOA with the sensor placement schemes of GA algorithm,WOA algorithm and PSO algorithm,it is found that the solution accuracy,optimization efficiency and stability of AWOA algorithm are better,indicating that AWOA algorithm can be applied to solve the sensor optimization of large bridges.placement problem.（4）On the main girder of the Binzhou Yellow River Highway cable-stayed bridge,damage conditions of different positions and different damage degrees are assumed,and then three damage identification methods are used to conduct damage identification research.Through the input modal parameters of the optimized placement of the sensors,the frequency sensitivity analysis method,mode shape sensitivity analysis method and modal curvature difference analysis method are used to detect one damage and two damages of the main girder of the cable-stayed bridge.for damage identification.The results show that the frequency sensitivity analysis method,the mode sensitivity analysis method and the mode curvature difference analysis method can all identify the occurrence of structural damage,and the mode sensitivity analysis method can roughly determine the location of the damage;Modal curvature difference analysis method,the first-order modal curvature difference of the structure can more accurately locate the location of the damage compared with the second-order and above modal curvature difference of the structure.