Study On Identification Method Based On Sub-space And The Curvature Model Of In-service Bridge Damage

Bridges in service will be inevitably suffered from a wide range of loading. Long-term of loading will cause structural damage to bridges.Reasonable design is the fundamental guarantee for structure security.However,it is not deeply understood on the complexity of large-scale structure,lots of uncertain or from time to time factors could not be controlled or predicted effectively,particularly in long-span bridges which are the most important large-scale projects in the lifeline of the city.Therefore,it is very significant and urgent for timely understanding of their "health" status.In this paper,by reading and researching of the relevant articles both from domestic and aboard,the development status of the existing detection technology has been summed up,based on this description,feasibility and necessity of two-stage testing,the idea of subsection structural damage detection using curvature modal has been put forward.Aimed at the special circumstances and requirements of the long-term health monitoring of the active bridge,the structural parameters of stochastic subspace identification method has been used,the Matlab procedures for the structural modal parameters of method identification of stochastic subspace has been conducted,the connection of curvature mode and structural strain have been analyzed;curvature model as the theoretical basis for structure inspection has been carried out. Using the single-stage damage identification of a continuous beam and multi-point damage detection of a simply supported beam,respectively,software SAP2000 calculation model has been established,the White noise which Matlab procedures made is added into the injury model,the reduction of stiffness to fulfill the structure damage has been used.basic theoretical framework based on the monitoring and identifying of sub-space method and curvature mode has been set up.The results showed that the curvature mode at the injury point had apparent differences between before and after injury,Which has been verify the sub-space and the curvature mode of the combination to accurately be determined the exact location of structural damage and the rough damage degree,and achieved the purpose of structural health monitoring and safety testing...