Research On Damage Identification Of Arch Bridge Suspender Based On Graphic Trajectory Method

Damage identification is the core of bridge health monitoring.In recent years,the long span and complex structure of the middle and lower arch bridges continue to emerge,but many arch bridge collapses have taken place at home and abroad,causing heavy casualties and economic losses.How to evaluate the health status of the structure in time and take measures to ensure the safe use of the structure has become an important role in the engineering field.As an important load-bearing component of arch bridge,suspender plays an important role in the safety of arch bridge,so it is of great significance to study the damage identification of suspender of arch bridge.Based on the research background of Xiying bridge,this paper studies the damage identification of suspender of through arch bridge.The main research contents as follows:(1)This paper summarizes the background and significance of structural damage identification,explains the research status of damage identification technology at home and abroad.All kinds of damage identification methods are introduced and compared in theory,application scope,advantages and disadvantages.It shows that single damage index is often difficult to fully reflect the information of the structure,and the damage identification technology combining multiple indexes should be developed.(2)Combined with the high accuracy of frequency test and the sensitivity of suspender tension to suspender damage,the damage identification technology of arch bridge based on image method is proposed.Taking the first-order vertical vibration frequency of the bridge deck and the first-order transverse vibration frequency of the arch rib as the dynamic component,combined with the tension of five typical suspenders as the static component,the seven element structure response vector(SSRV)is constructed to identify the damage of the arch bridge according to thechange track of the structure response vector.(3)The finite element model of Xiying bridge is established,and the characteristics of SSRV before and after the damage are described through a case study,and the accuracy of SSRV damage identification method based on image method is verified.The damage condition of arch bridge under single damage and special multiple damage is simulated.The track map of SSRV on phase plane is determined according to the direction angle of SSRV,and the damage is further located according to the difference of track map.Based on the theory of least square method,the linear regression equation is established,the damage degree is identified by SSRV 2-norm,and the relative error is calculated.(4)Simulate various damage conditions in different positions and degrees,analysis of the sensitivity of SSRV to damage,and verify the applicability of this method.The calculation formula and simulation formula of SSRV direction angle under different single damage and multiple damage types are deduced respectively.The theoretical data and actual data are substituted into the formula respectively,and the track map of SSRV in phase plane under different states of the structure is obtained.It is of engineering practical value to judge the construction and health status of the structure by the characteristics of the track map.