Finite Element Analysis For The Residual Stress Of Welded Box Column

With the advance of steel property and the develpoment of Nationaleconomy, many steel structure are used in buildings. The Welding column isan very important compression member in steel structure.In the Mid-late20th Century, Fritz Engineering structure Laboratory of Lehigh Universityfound that the initial geometric imperfections and residual stress are themost important factors that influence the ultimate bearing capacity ofcompression member. Residual stress is inevitable in the process of heatingand cooling cycles. Parabola model or broken line model about residualstress is broadly used to regulate residual stress in steel structure projects,but actually, residual stress is a complex three dimension stress field, thereis still a large gap. If more realistic residual stress used in the ultimatebearing capacity analysis, the more accurate results would be get.With the Maturity of three dimension thermal elastic-plastic finiteelement method, we can get the more accurate results about dynamic stressand strain, final residual stress and strain. The basic unknown quantity isnode temperature. According to the basic idea of finite element method, wedivide a welding column into an aggregation with finite small units.Increase temperature step by step and establish temperature interpolationfunction, we can acquire continuous temperature functions ( ,θx y,z,t) ofsolving area by using finite element calculation. Finally, we get the moreaccurate results about dynamic stress and strain, final residual stress andstrain.Based on ANSYS-a large finite element analysis software forcalculate and analysis platform,we can get three dimension final residualstress and strain of welding column by three dimension thermalelastic-plastic finite element method. APDL language is applied to build themoving heat source and coupled-field. According to the simulationcalculation result and compared the effects on residual stress in these threeaspects : height of column ,sequence of welding , number of weld bead.Ultimate bearing capacity of welding column have dropped by 20% by usingnonlinear buckling analysis of ANSYS.