Numerical Simulation Of Welding Residual Stress In Steel Bridge Panels And Analysis Of Influencing Factors

Orthogonal anisotropic steel bridge panels are widely used in bridge structural engineering because of their light weight,simple construction,clear force transfer and good mechanical properties.The bridge deck plate and the rib plate are connected together by welding,and the high temperature generated by the welding process will cause uneven plastic deformation of the structure,thus generating welding residual stresses.The welding residual stress will reduce the mechanical properties and service life of the structure.With the massive use of orthotropic anisotropic plate deck structures,this problem is becoming more and more prominent and has become one of the hot spots of research concerns.In order to investigate the distribution law of welding residual stresses in orthotropic anisotropic deck plates of steel bridges,the thesis takes the commonly used closed U-rib deck plates as the research object,focusing on the distribution law of welding residual stresses in the longitudinal stiffening ribs of the deck plates,the main research work and research findings are:(1)The theory of finite element analysis of welded residual stress is summarized.The heat source model parameters are developed based on relevant theories,and the bridge deck plate U-rib finite element model is established for calculations.The simulation results are compared with existing research test data,and the results show that the model in this thesis is reasonable.(2)The effect of shape parameters of the double ellipsoidal heat source model on the welding residual stresses is studied.The establishment of different shape parameters of the heat source model and bridge deck plate U-rib finite element model,focusing on the shape parameters on the peak weld temperature and the peak longitudinal welding residual stress of the top plate,the establishment of response surface regression equation and parameter significance analysis.The results show that:the shape parameters of the double ellipsoidal heat source model for the peak weld temperature and the top plate longitudinal welding residual stress is more significant.The order of significance of the parameters affecting the peak temperature at the centerline of the top plate weld is double ellipsoidal heat source model heat source half-width,ellipsoidal rear half length,ellipsoidal front half length,and the order of significance of the parameters affecting the peak longitudinal residual stress in the top plate is double ellipsoidal heat source model ellipsoidal rear half length,heat source half-width,ellipsoidal front half length.(3)The influence of different construction and welding parameters on the steel bridge panel longitudinal stiffening ribs of the law of the welding residual stress is studied.The top plate thickness,rib thickness and welding speed as parameters to explore its influence law on the residual stress distribution of the bridge deck plate Urib and bridge deck plate V-rib.The results found that,when the welding parameters,for the bridge deck plate U-rib,the top plate and rib plate longitudinal welding residual stress peak and distribution width decreases with the increase in the top plate thickness,the top plate and rib plate thickness direction of the peak welding residual stress increases with the increase in the thickness of the rib plate,increase the welding speed will increase the longitudinal residual stress in the rib plate weld area;for the bridge deck plate V-rib,the top plate weld area equivalent welding residual stress.With the increase in the thickness of the rib plate decreases,the longitudinal welding residual stress of the rib plate decreases with the increase in the thickness of the rib plate,increasing the welding speed will increase the longitudinal welding residual stress of the rib plate in the weld zone.(4)The welding sequence on the bridge deck plate U-rib top plate unit of the welding residual stress field distribution is studied.According to the three welding schemes,the analysis of welding residual stress distribution characteristics.The results show that: the use of symmetric welding sequence,longitudinal welding residual stress in the weld area is more uniformly distributed,the peak is relatively low;the use of asymmetric welding sequence,longitudinal welding residual stress in the weld area is extremely uneven distribution,the peak is relatively high;the use of sub-sequential welding sequence,due to a significant reduction in the heat-affected area of welding,longitudinal welding residual stress peak significantly reduced;can prove that the welding process on the welding Residual stress has a significant impact and great complexity,the overall can be concluded to take symmetrical welding and reduce the welding heat-affected area of the welding sequence is more favorable.