Research On Distribution Of Residual Stress In Q690High Steel Pipe

Has the characteristics of high strength, high strength steel component section inthe same design load can be reduced, thus saving material, high economic efficiency,has been widely used in bridges, power tower and span spatial structure, while Residualstress will affect the pressure stability of the steel structural members, fatigue fracture,brittle fracture and stress corrosion cracking. Axial compression stability bearingcapacity of steel pipe is associated with the overall stability factorφ of component, theoverall stability factor φ of component is associated with the materials, mechanical,geometric imperfections, and affected by the component constrained conditions. Amongthem, the component constrained conditions can be considered by effective length factor,geometric imperfections (initial bending and initial eccentricity) can be valuedaccording to code for acceptance of construction quality of steel structures, there is nodifference of these two influencing factors for high-strength steel and ordinary steel, butthe impact of mechanical defects: residual stress varies greatly. Therefore, it isnecessary to study the residual stress distribution of high-strength steel pipe in order tolay the foundation for the determination of the overall stability factor for the steel pipecolumns.In this paper, the residual stress distribution of Q690high-strength steel pipe wastested by blind-hole method and sawing method, with a detailed description of the stepswhen using these two methods to test the residual stress, and the final test results werecompared and analyzed. Then, based on the test results, using the finite elementsoftware ANSYS to simulate the welding residual stress, the temperature field and stressfield was linked by thermal-structure coupling analysis function, and analyzed the three groups of finite element model for a total of12. Finally, the test data and numericalsimulation results summarized.The main results are as follows:(1) Using blind-hole method and sawing method to test the residual stress of piperespectively, by comparing the test results measured by these two methods can be foundthat when using sawing method, make sure the accuracy of hand-held strain gaugemeasurement, not more than0.001mm;(2) Test the not galvanized steel pipe and galvanized steel pipe of the samecross-section, then the galvanization effect on residual stress distribution are obtained.The test result shows that the residual stress of the steel pipe galvanized is significantlyreduced;(3) After inspected the welded steel pipe end plate stiffener influence on steel pipecross section of the longitudinal residual stress. The results found the effect is verysmall, needn’t consider in the actual project;(4) According to the processing plant specimen processing and welding parameters,using ANSYS finite element model to simulation the temperature field and stress field,the numerical simulation results of the longitudinal residual stress distribution isobtained. The accuracy of the model was proved by comparing with test results. Thenthe longitudinal residual stress of different cross section forms of Q690high-strengthsteel pipe was simulated;(5) Q690high-strength steel pipe cross-section longitudinal residual stress andyield stiffness ratio was significantly less than the ordinary steel can be found throughthe analysis of the test results and numerical simulation results, at the same time, thecross-section longitudinal residual stress distribution of Q690steel was proposed andput forward the mathematical expression of residual stress calculation which provides abasis for future practical application.