Study On The Welding Heat Effect On The Mechanical Behavior Of Structure With PCSS Shear Connector

This paper is financed by the application of basic research projects of Ministry of transportation entitled with "Basic theory research of large span steel truss-concrete composite continuous rigid frame bridge "(Project number:2013 319 814 040).Professor Zhou Zhixiang proposed a new type of shear connector entitled with PCSS shear connector.In this paper,the finite element software ABAQUS is used for welding simulation modeling,and the effect of welding head on the composite structure with PCSS shear connector is explored,and the main research work includes:? According to the structural characteristics and quick assembly construction method of the steel truss-concrete composite continuous rigid frame bridge,the types of PCSS shear connector are compared and optimized.The steel girder and the PCSS shear connector are bond as a whole through fillet welding,which is good for the quick assembly construction method and quality control.Besides,PCSS shear connector has large shear capacity,which guarantees the overall mechanical performance of the composite structure.? The user subroutine of the Gauss double ellipsoid welding heat source model is compiled.By using the subroutine,the whole welding process is realized,besides,the welding parameters such as output power,geometrical size and moving speed can be easily modified.By using the solid-shell element and the cross-scale modeling method,the number of elements and that of the integration points are significantly reduced,thus the working efficiency of the computer is improved.By using the "Model Change technology" in ABAQUS software,the welding seam appears successively is realized.? The whole welding process is simulated and analyzed,results show that the maximum temperature of the steel components reached 1500?,and the phenomenon molten pool appeared,the maximum temperature of local concrete reached 3800C.The welding residual stress is mainly concentrated in the vicinity of the weld area.Stress concentration,which reached 90MPa,appeared at the root of flange plate,however,it still less than the yield stress of Q345 steel.In the welding process,the main girder is cambered overall,the maximum of camber reached 0.14mm,the last residual camber is about 0.1mm.? The welding process of steel girder with initial stress 50MPa,100MPa and 150MPa are simulated respectively.Comparison of each results are carried out,the results show:the initial stress has a certain influence upon the residual stress,the larger the initial stress is,the lower the residual stress is.? The damage factor of concrete at high temperature is derived.The thermal damage zone in the model is roughly the same as the test.The push-out simulation test of PCSS shear connector considering or not considering the welding head is compared in ABAQUS.The results show:the ultimate slippage in two cases are the same,the ultimate shear capacity of PCSS shear connector considering the welding head is 3.2%less than that of the other case,which indicates the effect of welding head to the shear capacity of PCSS shear connector can be neglected.