Theoretical And Experimental Study On Damage Identification Of Shear Joints Of Steel-Concrete Composite Beams

Steel-concrete composite beam structures are widely used in long-span bridges and other complex structures.Shear connections in structures are key components that connect steel and concrete members as a whole,and rust occurs when loads,environmental impacts,lack of normal maintenance and maintenance,and natural disasters occur.Loosening and even shedding can reduce the combined action of composite beam,reduce the overall performance and bearing capacity of structural members,and even lead to failure of members or structural damage.However,it is difficult to diagnose the damage by common detection methods.Therefore,based on the characteristics and present situation of the steel-concrete composite beam shear joint,the damage location and extent of the shear connection are identified by experimental research and numerical simulation analysis.The research results are of great significance to ensure the overall performance of composite beam structure,prolong its service life and avoid the occurrence of safety accidents.The specific research work carried out in this paper is as follows:1.The existing damage identification methods based on artificial intelligence and dynamic test data are discussed.The curvature modal values under arbitrary boundary conditions are calculated based on the curvature modal method and the central difference method.The effectiveness of this method for structural damage identification is verified by numerical simulation of a simply supported beam.2.The analysis models of steel-concrete composite beam and fiberglass composite beam are established by using the finite element software MIDAS.The damage of shear joints is simulated by changing the elastic modulus of joints.The modal parameters(frequency and mode shape)of the composite beam are obtained based on modal analysis,and the damage location and degree are identified by the curvature modal change.3.On the basis of numerical calculation,an experimental study on glass fiber reinforced plastics composite beam was carried out,the DH610 acceleration sensor and DH5922 intelligent signal acquisition analyzer are used to monitor the composite beam,and the natural frequency and vibration mode of the composite beam are obtained.Then the damage location and degree of glass fiber reinforced plastics composite beam are identified based on curvature mode method,which proves the validity of the method in this paper.