Research On Finite Element Model Modification And Early Warning Based On Response Surface-whale Algorith

Large and complex bridge structures often rely on refined analysis of finite element models to achieve structural damage location and identification,health monitoring,and safety warning applications.Therefore,it is extremely important to establish an accurate finite element model that approximates the actual stress situation of the bridge.This paper attempts to combine the response surface method with the whale algorithm to obtain a more accurate finite element model.Based on this model,the early warning value of the bridge health monitoring system is set.The main research contents of this article include:(1)The basic theory of finite element model modification is studied.Three methods for selecting correction parameters are introduced,with emphasis on sensitivity analysis.Six widely used experimental design methods are described,and their advantages and disadvantages are analyzed.In this paper,a central composite experimental design is selected.Then,the principle and implementation process of the response surface method are described in detail.Finally,an objective function that approximates the theoretical response value infinitely with the measured value is constructed,and the principles and operating steps of genetic algorithm and whale algorithm are introduced,laying a theoretical foundation for the modification of the real bridge finite element model.(2)Extract the measured data from the static load test of a newly built simple supported beam,and optimize the response surface equation of the beam using Whale algorithm and genetic algorithm.The two algorithms have similar effects on static parameter correction and optimization,and the Whale algorithm is slightly superior.The deflection response error of the finite element model modified based on the response surface whale algorithm has been reduced from 8% to less than 3%,and the strain response error has been reduced from 30% to less than 10%.The modified results preliminarily verify the preliminary feasibility of the practical application of the model modification method.(3)The Whale algorithm is used to compare the genetic algorithm with response surface methodology to verify the effectiveness of model modification for concrete filled steel tubular arch bridges.Using highly sensitive parameters to be corrected,and using central composite experimental design input parameters,an accurate response surface model is obtained by fitting.The optimization effect of the two algorithms on response surface is significantly better than that of genetic algorithm.The modified parameters were substituted into the initial model to verify the modified parameter response.Based on the response surface whale algorithm,the modified finite element model’s deflection response error was reduced from 22% to less than 5%,the strain response error was reduced from 33% to less than 10%,and the frequency response error was reduced from 18% to less than 3%.The accuracy and efficiency of the response surface whale algorithm in model modification of complex bridge structures are verified.(4)Based on the revised finite element model and in accordance with the Technical Specification for Structural Monitoring of Highway Bridges(JT/T 1037-2022),a health monitoring system for the Jiangkai River Bridge was designed and established.Then,the quantitative indicators of early warning values for the environmental category,action category,structural change category,and structural monitoring data change category of the Jiangkai River Bridge are set.Based on the static response value of the main arch ring,the most unfavorable load combination for the structure is selected,and the early warning values for 10 types of response parameters such as arch crown displacement,boom force,and beam displacement of the Jiangkai River Bridge are calculated,with0.8 times and 1.0 times of the design value serving as the second and third level early warning values,respectively.Compared to the pre correction warning value of the structural model,the revised warning value decreased by about 5% to 10%.Comparing the modified model with the measured level 2 early warning value,the two are very close.It further indicates that the modified model warning value is more accurate and sensitive.The modified finite element model can effectively assist the bridge health monitoring system and management and maintenance units in making correct emergency interventions.