Numerical Simulation Of Temperature Field And Residual Stress Of RDF Crack Rewelding In Orthotropic Steel Deck

The orthotropic steel bridge panel is widely used in the deck structure of modern steel Bridges,and the composite steel plate welded with longitudinal rib,floorbeam and roof is the main structural form of orthotropic steel bridge panel.The residual stress generated by welding,the transverse bending stress generated under the action of wheel load and the defects such as incomplete penetration at the welding root cause the welding heel to crack and develop along the roof longitudinally.The crack that runs through the panel between the beams is called RD crack and the crack that runs through the panel on the beams is called RDF crack,the most common methods to repair the cracks is to remove the weld and then reweld.However,if the residual stress caused by rewelding process is neglected,the structure is likely to crack again after repair.The study of residual stress of RDF crack rewelding is of great significance to the long-term operation of bridges.The residual stress of RD crack rewelding is usually simulated numerically by changing welding parameters such as welding speed,groove angle and groove length.The structure of RDF crack is more complex than that of RD crack.The numerical simulation of residual stress in RDF crack rewelding has not been reported.In order to deeply understand the welding residual stress of RDF crack rewelding repair from a theoretical perspective,the authoer makes an in-depth study from the basic topic step by step.The numerical simulation of RDF crack rewelding repair process is presented in the last chapter in this paper.Main results of this paper are as follows:(1)In this paper,the optimum welding parameters of the pool shape of 6mm roof are obtained.The value of double ellipsoid heat source shape: A = 1.5d(weld width),B= 1.5d(weld depth),C1 = 0.5d(the length of the first half axis of the ellipsoid),C2 = 2d(the length of the second half axis of the ellipsoid),D is the weld width;Welding current:290A,welding voltage: 28 V,welding speed: 5 mm/s.(2)The longitudinal residual stress distribution of rib and roof weld is complicated by transverse diaphragm structure.When the initial stress field is considered,the transverse residual stress variation on one side of the diaphragm and the weld area is more prominent than the longitudinal residual stress variation.Considering the influence of initial stress field is very important to master the residual stress distribution in rewelding process.(3)In order to reduce the thickness of the welding residual stress plate of the whole member,it is recommended to take the roof thickness of 16 mm,the rib thickness of 8mm and the diaphragm thickness of 8mm.(4)The relationship between the rewelding parameters of RDF crack and the peak of residual tensile stress is functional.The peak value of transverse residual tensile stress increased with the increase of roof thickness,while the peak value of longitudinal residual tensile stress decreased with the increase of weld length,and the peak value of longitudinal residual tensile stress increased with the increase of weld length.