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Research On Damage Identification Of Small And Medium-span Concrete Bridges Based On Displacement Influence Lines

Posted on:2022-10-21Degree:MasterType:Thesis
Country:ChinaCandidate:Y W ShengFull Text:PDF
GTID:2532307106967399Subject:Civil engineering
Abstract/Summary:PDF Full Text Request
Bridge structures in the operating conditions will bear a variety of actions,inevitably there will be performance degradation,all kinds of diseases,damage accumulation and other conditions,which will cause hidden dangers to the safe operation of bridge structures.Therefore,the damage identification of bridge structure is a hot issue in bridge engineering field at present.Rich research was done and a lot of research results have been accumulated.This paper is based on the influence line method and takes small and medium span concrete bridges as the research object.The full text is carried out from four aspects:theoretical analysis of influence line,identification and damage location of influence line based on regularization method,quantification of damage degree based on finite element theory of influence line and damage identification of real bridge based on influence line.The main work is as follows:(1)Based on the principles of mechanics,the analytical solution of the influence line of the beam system is deduced.It is theoretically explained that the index can be used for the damage identification of the structure,and the influence line and its various derivative indexes are graphed to verify the analysis.A numerical example is used to illustrate the method of determining the damage location by the two indicators,which are influence line difference and its derivative.(2)Identifying the influence line from the data is a typical inverse problem.Relying on the vehicle-bridge coupling analysis,the process of vehicle crossing the bridge is simulated and the response is calculated.The response result and the information of the simulated vehicle and bridge are used to establish an equation to identify the influence line.Due to the ill-posed problems,the recognition based on the regularization method is introduced,and the penalty is added to limit the increase of information to help find the numerical solution of the problem that meets certain conditions.The damage identification based on this method can locate the damage area,but noise will also interfere with the result of damage location in some cases.(3)Through the finite element theory,the influence line can be related to the flexibility matrix,etc.With the help of the existing abundant damage identification methods on the stiffness and flexibility matrix the degree of damage dan be identified.The identification error of this method is small,and the identification effect is good.(4)Take a certain bridge load test as the background,the process of actual load test is simulated by vehicle-bridge coupling simulation loading,and the displacement influence line of the structure is identified and analyzed;a new method of verifying the effect of the influence line identification is proposed,which is to test the vehicle according to the axle weight simulation is loaded on the identified influence line,the corresponding peak displacement is calculated,and the actual measured displacement is compared to evaluate the effect of the influence line identification.The result shows that there is an error between them,which proves that the influence line identification method proposed in this paper has a good identification effect in actual engineering and has certain engineering application significance.After applying the influence line damage index to engineering practice,it can be proved that it can be applied to the identification of damage location.
Keywords/Search Tags:Bridge damage identification, Deflection influence line, Ill posed inverse problem, Regularization method, Load test
PDF Full Text Request
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