Study On Damage Identification And Condition Evaluation Techniques For Railway Bridges

With the development of the national economy, the transportation volumes of the railway increase dramatically, so the dynamic action of vehicles on the bridge increases greatly, which brings negative impacts on the bearing capacity and service life of the bridge. In this thesis, the damage identification technique of the bridge structures, the choice of damage models, the influence laws of track connections, supporters and all kinds of diseases, such as subsoil scouring, on the lateral vibration characteristics of the bridge are systematically analyzed.First of all, the basic methods and theories in the field of bridge inspection and damage identification are introduced. And then, the damages of the continuous beam and single-pier bridge system are identified by the modal curvature method, in which the stiffness-decline damage model and the crack model are compared. The influence of changes of the boundary conditions, such as track connections on the bridge and the bridge supporters on the vibration characteristics of the bridges are studied in order to propose useful reference for future modal identification works. Finally, the diseases of the bridge substructures with spread foundation, pile foundation and caisson foundation are simulated by numerical methods and some engineering cases are analyzed.Ultimately, this thesis obtains some valuable conclusions. Furthermore, the contents that need to be improved or studied thoroughly are summed up. And the development prospects of the bridge damage identification techniques in future are visioned.