Study On Local Stability Of 800MPa High-strength Steel Welded Section Axial Compression Members

With the progress of steel production process,the high strength steel has been more and more widely used in the building and bridge structure.To study the engineering application of 800 MPa high strength steel welded section members,the local stability and the design method of the high strength steel welded section axial compression member is researched.According to the two common welded section used in practical engineering,31 members are designed.Four I-section and T-section members were tested to investigate residual stress of high strength steel construction.And Twelve I-section and eleven T-section compression members were tested under static loading to investigate the effects of width-thickness ratio,residual stress,buckling coefficient and embedding coefficient on local buckling.The stability design method of high strength steel welded section axial compression members were proposed by revealing the connection between the bearing capacity,the strength,and width to thickness ratio of the high strength steel.The distribution model were produced based on residual experimental study.The results that local buckling influence ultimate load bearing capacity of plate and the stiffness out of the plate does not affect the stiffness of the member are obtained by studying the axial loading test and influence of the steel material and local geometric imperfection on local buckling load and ultimate bearing capacity.Comprehensive three-dimensional finite element models were presented for test specimens using the ANSYS nonlinear finite element program,which considered the initial geometric imperfections and residual stresses.The finite element results are in good agreement with the experimental results.The results show that the ultimate bearing capacity increases with the increase of width-thickness ratio,while the increasing amplitude decreases.And the ultimate bearing capacity decreases with the increase of slenderness ratio.The influence of residual stress on ultimate bearing capacity,less than 5%,is not obvious.The limiting condition of the width thickness ratio of high strength steel welded I-section and T-section axial compression were proposed based on experimental study and simulation analysis.A design method is established according to the the formula of the limitation of the width-thickness ratio.Compared with experiment data demonstrated,the proposed formulas can accurately predict the stability capacity of compression members,and can showed these methods are feasible.The purposes of research can provide the basic experimental data for illustrating the destabilization principle of local buckling of high strength steel welded section axial compression members,refining the material of high strength steel and improving the exiting design theory of steel structure,which can develop the application and extension of high strength steel.