Research On The Local And Overall Interaction Buckling Of High Strength Steel Welded I-section Column Under Axial Compression

The steel strength is designed Q235~Q420 in Code for design of steel structures of our country, the design method of high strength steel is just modify parameters on the basis of ordinary steel. the high strength steel welded I-section members under axial compression can not achieve their full potential if web depth-to-thickness of ratio within the limit stipulated in the specification, Transfinite web depth-to-thickness ratio prone to local buckling, but local buckling of web does not means the loss of bearing capacity,In order to achieve post-buckling strength, the web depth-to-thickness should be relaxed appropriately. which can save steel and lower cost.A finite element model is established by ANSYS to analysis high strength steel Q460 welded I-section axial compression column ultimate capacity. the initial geometric imperfections(both the global and local deflections) and residual stresses, as well as the geometrical and material nonlinearities were be considered. the reliability of the finite element model was validated by experimental results. By changing the web depth-to-thickness ratio flange width-to-thickness ratio and slenderness ratio to analysis their influence on the local and overall interaction buckling of axial compression columns. Without considering the residual stress for some members of the Q460 and Q235 steel columns were re-calculated the ultimate capacity and analysis the influence of residual stress for different levels of steel. combined with the design formulas of specification comparing the results of the finite element to modify the design formula of DSM method.The study shows that the ultimate capacity of column is reduced when increasingthe web depth-to-thickness ratio, because of section stiffness decrease; Increasing flange width-to-thickness ratio will decrease the restriction in the web, the ultimate capacity of the columns is reduced; Along with the slenderness ratio of column increasing, the overall stiffness decreases, so the ultimate capacity will be reduced; The initial defect is one of important factors to reduce the ultimate capacity. Existing design method can not accurately calculate the Q460 steel welded I-section ultimate capacity of axial compression column,putting forward modified formula for DSM, which indicating the results are in good agreement with the finite element results.