Welding Residual Stress And Fatigue Performance Simulation Analysis Of Steel Bridge Deck U-rib

The orthotropic bridge deck structure is composed of the upper and lower parts of the bridge panel and the transverse and longitudinal stiffeners.Compared with the ordinary reinforced concrete structure,it has many advantages.In general,the U-rib and the bridge panel are welded together into a whole,and the high temperature generated by welding will lead to plastic deformation of the structure,and then generate residual stress.Under the joint action of wheel load,residual stress and other factors,the stability and fatigue performance of the structure will be affected to some extent.In this thesis,the steel bridge panel and U-rib structure are taken as the research object,and the residual stress distribution and the fatigue life of the structure under the influence of welding process are studied by ABAQUS and FE-SAFE co-simulation.The main work contents are as follows:(1)The research results of welding residual stress and weld fatigue in U-rib bridge panel were summarized,including the generation mode,distribution law and harm of residual stress.Explored the damage mechanism and related influencing factors of fatigue in U-rib welds.The shortcomings were pointed out,and the research direction of this article was determined.(2)Organize the finite element analysis of welding and the theories related to structural fatigue,including the related theories of welding temperature field and stress field,fatigue calculation methods,etc.The thermophysical properties of welding materials at different temperatures were summarized.The coupling sequence in numerical simulation is determined,which lays the foundation for the following simulation analysis.(3)The model was established in ABAQUS,and the appropriate heat source model was selected to write a subroutine for simulation analysis.The temperature field was analyzed first,and then the stress field was analyzed on the basis of the temperature field to obtain the distribution of temperature and residual stress.The variation law of residual stress was described from three aspects: along the weld,perpendicular to the weld and along the plate thickness,and the variation law of residual stress under the change of plate thickness and groove Angle as well as welding speed was studied.The results show that the maximum residual stress occurs in the roof and U-rib near the weld.The maximum value of residual tensile stress decreases with the increase of roof thickness and the increase of groove Angle.The increase of welding speed will reduce the peak residual stress.The results of numerical simulation and existing test results are compared and analyzed.The results show that although the simulation results and existing test results are different,they are consistent on the whole,which verifies the effectiveness and accuracy of numerical simulation.(4)Based on the residual stress field,the fatigue life of the structure is analyzed,and the variation trend of the fatigue life is studied by changing the structural parameters such as plate thickness and groove angle.The results show that the residual stress reduces the fatigue life and fatigue safety factor of the structure.Increasing the plate thickness can improve the fatigue life of the structure,and when the groove angle is between 45° and 55°,the durability and safety life of the structure are more reasonable.