Experimental Research On Spatial Grid Method Model And Model Modification Of PC Composite Box Girder Bridge With Corrugated Steel Webs

As a new type of steel-concrete composite structure,the corrugated steel web PC composite box girder bridge effectively overcomes several defects of the traditional prestressed concrete box girder,and has been popularized and applied with its unique advantages.For the structural analysis of PC composite box girder with corrugated steel webs,the spatial link model,plane beam grid model and solid element model all have some incompatibility to varying degrees in practical applications.In recent years,a practical and refined model — spatial grid model has been introduced into the structural analysis of PC composite box girder with corrugated steel webs.However,the current research results shows that there are relatively few research results on the application of spatial grid model to the analysis of mechanical behavior of real bridge structures.Therefore,the research on the application of the spatial grid model in the composite box girder bridge engineering has significant engineering significance.In this paper,a PC composite box girder bridge with corrugated steel webs of a viaduct in Taiyuan City is used as the research object,and the spatial grid model is applied to the mechanical analysis of composite box girder structures.The spatial grid using the overall web division method is explored.The analysis method constructs the accuracy of the finite element model of the solid structure,and studies effective methods to modify the parameters of the spatial grid model based on the design drawings to improve the accuracy of the numerical analysis of the model.The above research has certain engineering application value.The main research contents of this paper are as follows:1.Describes the current research and application status of PC composite box girder bridge structure analysis methods and model correction methods with corrugated steel webs,and puts forward the research goals of this thesis.2.A PC composite box girder bridge with corrugated steel webs is selected for load test,and some measured data on the static and dynamic load response of the structure are obtained as the test basis for the subsequent space grid model research.3.According to the design data of the PC composite box girder bridge with corrugated steel webs and the structural characteristics of the composite box girder,based on the ANSYS software platform,the space of the PC composite box girder bridge with corrugated steel webs is constructed using the method of dividing the web as a whole grid model.Among them,for the corrugated steel webs and steel-concrete joints,the equivalent spatial grid elements are obtained through the principle of equivalent stiffness conversion based on the plate and shell theory.4.Using the loading conditions of the real bridge load test,the numerical simulation analysis of the spatial grid model of the composite box girder bridge under static load and the numerical analysis of the dynamic performance of the structure under free vibration were carried out.Compared with the test data of the real bridge the maximum relative deviation of the first three-order vertical natural frequency values calculated by the model is 15.46%,and the maximum relative deviation of the deflection value calculated by the model is 14.2%.5.In view of the deviation between the established spatial grid model of composite box girder and the experimental data to a certain extent,this paper further carried out the experimental research of model correction for the initial spatial grid model.Based on the response surface method,the design parameters are used as independent variables,and the objective function is constructed by using the calculated and measured values of the vertical and forward third-order natural frequencies for iterative optimization,so as to realize the modification of the spatial grid model.Then the space grid is loaded according to the static load test loading conditions,and the relative deviation of the calculated deflection is compared with the measured value,and the relative error is reduced to less than 10%.It shows that the spatial grid model modification method based on the response surface method can be used in the effective evaluation of the safety performance of the actual bridge operation.