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Research On Welding Residual Stress Of Fully-Permeated In Steel Bridge Decks Stiffened With U-Shaped Ribs

Posted on:2019-04-25Degree:MasterType:Thesis
Country:ChinaCandidate:S T ZhouFull Text:PDF
GTID:2322330563954571Subject:Architecture and civil engineering
Abstract/Summary:PDF Full Text Request
Orthotropic steel decks stiffened with U-shaped ribs are extensively applied in bridge deck structures of long-span bridges today.With the advantage of improving the mechanical characteristics of the fillet welds on U ribs and ameliorating the welding quality,the full-penetration welding technique began to adopt in the joints of steel bridges.However,the complex distribution of welding residual stress,which has a very adverse impact on the fatigue strength for the welding site affect the durability and service life of the steel bridge.Therefore,basing the full-penetration welding technique,the thesis studied the distribution of the orthotropic steel decks stiffened with U-shaped ribs by the method of experiment and numerical simulation.The main contents include:(1)The development and application of orthotropic steel decks stiffened with U-shaped ribs were introduced.The superiority and research status of full-penetration welding technique were described from the perspective of welding technique on bridge steel structures.Then,the classification,generation mechanism and influence on the steel bridge structure of the welding residual stress are summarized respectively,including the status and inadequacies researches for testing and numerical simulation.Based on these work,the research content of this thesis were established.(2)The application of finite element method in welding were discussed systematically,The basic form of heat conduction in the nonlinear three-dimensional transient temperature field included.By governing differential equations,a specific method for solving the temperature field is derived from the theoretical analysis.The theoretical derivation of the coupling of temperature field and stress-strain field is introduced by base of theories of thermal elastic-plastic.(3)An orthotropic deck stiffened with U-shaped rib specimen of Q345 q D which consists of a thickness of 14 mm for top plate and 8 mm for U-rib was designed.To weld the U-rib fillet of the specimen,single-side welding with both-side bead forming technology was adopted.Then,the 3D(Three-Dimensional)printing technology was used to optimize the test device,and the surface of weld seam,U-ribs,and top plate were tested by use of the blind hole method for the purpose of exploring the vertical and horizontal residual stress distribution laws.(4)Based on finite element analysis software ANSYS,three-dimensional numerical simulations of temperature field and stress field of orthotropic U-rib stiffened plates were performed.HYPERMESH was used to build the model's geometric mesh.Through the finite element calculation,the magnitude and specific distribution of the welding residual stress are obtained.The correctness of the numerical simulation is verified compared with the measured values.(5)The magnitude and distribution of the welding residual stresses of orthotropic steel decks stiffened with U-shaped ribs were analyzed by numerical simulation from the perspective of the welding procedure(penetration rate,welding speed)and geometry(the thickness of top plate).These welding parameters which can provide reference for the welding procedure and geometric structure design.
Keywords/Search Tags:full-penetration welding, orthotropic steel bridge deck, U-shaped rib, welding residual stress, blind-hole method, numerical simulation, parameter analysis
PDF Full Text Request
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