Research On Single-side Full-penetration Welding Of U-shaped Stiffener Bridge Deck

The U-shaped stiffened rib bridge deck has strong advantages and costeffectiveness,and is widely used in major bridges at home and abroad.However,fatigue damage is prone to occur at the joint between the U-rib and the deck without penetration welds.Therefore,engineers put forward the full penetration welding technology,which can effectively inhibit the occurrence of fatigue failure.But the currently commonly used full penetration welding method has disadvantages such as complex welding process,large number of weld passes,large welding residual stress and welding deformation,and high welding cost.In view of these problems,this paper proposes a U-shaped stiffener bridge deck single-sided full-penetration welding technology using U-rib lining brackets,which realizes the U-rib and deck under the condition of no opening and one weld seam welding The single-side full-penetration welding connection is completed,which overcomes the problems of missing welds and incomplete penetration of single-side full-penetration welding,improves the production efficiency of the U-shaped stiffener bridge deck,and significantly reduces its production cost.In this paper,the proposed U-shaped stiffener bridge deck singlesided full-penetration welding technology is studied as follows:(1)Summarize and summarize the research status of full penetration welding technology,welding numerical simulation and blind hole stress testing at home and abroad,point out the shortcomings and problems existing in the research status,define the research objectives of this paper,determine the research content and reasonable technical route.The basic theory and principle of welding numerical simulation are expounded and the method and principle of analyzing and calculating the temperature field and stress field of single-side full penetration welding of U-shaped stiffened ribbed bridge panel are obtained.(2)In order to study the relationship between the penetration rate of the singleside full penetration welding technology of U-shaped stiffener bridge panel proposed in this paper under a specific welding process,and to explore the numerical characteristics and distribution of the welding temperature field,post-welding stress field and post-welding deformation,the finite element analysis software ABAQUS was used to analyze the single-side full penetration welding process of U-shaped stiffener bridge panel.Through the analysis of the results,the welding conditions of the single-side full penetration welding connection and the welding quality assurance measures were obtained under the welding current of 564 A,welding voltage of 35 V and welding speed of 7mm/s,and the quantitative relationship between the welding temperature field,post-welding stress field and post-welding deformation was numerically simulated.(3)In order to verify the reliability and accuracy of the proposed single-side full penetration welding technique of U-stiffened ribbed bridge panel,the single-side full penetration welding test of U-stiffened ribbed bridge panel was carried out.The welding test shows that the welding technology can be implemented in the actual production,and the welding seam is smooth and full,no welding leakage occurs at the welding root,except for a few parts of the arc area is not penetrated,the remaining areas all reach 100% penetration rate.In addition,the residual stress of the specimen is basically consistent with the test value in the low-stress area far away from the weld,while the test value is far greater than the numerical analysis value in the high-stress area near the weld.The main reason is that the blind hole method in the high-stress area will cause the hole edge plastic effect,which leads to a large error in the residual stress test results.In view of this error,an iterative correction method of residual stress based on numerical simulation correction and coefficient is proposed,and the residual stress values before and after correction are compared with the real values.The comparison shows that the iterative correction method of residual stress proposed in this paper can effectively solve the problem of large error of residual stress testing by blind hole method in high stress area,and the correction accuracy and efficiency are high.The correction results are unique and convergent.Finally,the residual stress characteristics and distribution of five typical test paths of welded specimens were obtained by using the modified method.(4)In order to prove that the single-side full penetration welding technology of U-stiffened ribbed bridge panel proposed in this paper has certain advantages,this paper takes the common double-side full penetration welding technology as the reference object,carries on the numerical analysis to the double-side full penetration welding process of U-stiffened bridge panel,and carries on the comparative study to the three kinds of mechanical behaviors of U-stiffened ribbed bridge panel welded by two kinds of welding technology.The results show that single-side full penetration welded U-shaped stiffener bridge deck has more advantages than double-side full penetration welded U-shaped stiffener bridge deck.Through the research on single-side full penetration welding of U-shaped stiffened ribbed bridge panel,a better full penetration welding technology is provided for the production and manufacturing of U-shaped stiffened ribbed bridge panel,which not only improves the welding quality,welding efficiency and fatigue strength of welded parts,but also reduces the production cost,welding residual stress and welding deformation,and provides a technical basis for the development of U-shaped stiffened ribbed bridge.It also lays the theoretical support for the development of steel structure bridge.