Study On Local And Global Interaction Buckling Of Q690 High Strength Steel Welded I-shaped Axial Compression Columns

With the continuous improvement of China's steel production technology,high strength steel has been widely used in modern engineering structures.High strength steel is greatly improved relative to the strength of ordinary steel.Therefore,under the premise of ensuring the bearing capacity to meet the specification requirements,the thickness and cross section area of the steel plate are less than that of ordinary steel members.Therefore,the self weight of the structure is reduced,the utilization ratio of the resources is improved,and the good social and economic benefits are obtained.However,with the decrease of wall thickness and section area,the width-thickness ratio,height-thickness ratio and slenderness ratio of the steel structure have different degrees of increase,even beyond the existing standard limit value,which is bound to put forward new challenges to local stability and overall stability of high strength steel.At present,there is a deep understanding of the local and global stability problems of common steel structures.However,the study on the stability of high strength steel,especially for high strength steel members with a strength greater than 690 MPa,is relatively less.In view of this,this paper intends to study the correlation between the local and global stability of Q690 high strength steel welded I-shaped column under axial compression:(1)The numerical model of welded I-shaped compression column with different flange width to thickness ratio,web thickness ratio and slenderness ratio is established by using ABAQUS finite element software.The model considers the influence of initial defects,component material nonlinear and geometric nonlinear factors on the bearing capacity,in order to study the influence of web thickness ratio,flange width thickness ratio,slenderness ratio and residual stress parameters of welded I-section columns on the local buckling ultimate bearing capacity.(2)Through the analysis of finite element simulation results,we can find: flange width-thickness ratio,web thickness ratio and slenderness ratio are important parameters which influence the ultimate buckling strength of the welded part;With the increase of flange width-thickness ratio and web thickness ratio,the ultimate bearing capacity of the members increases,but the dimensionless bearing capacity decreases;With the increase of the slenderness ratio,both the ultimate bearing capacity and the dimensionless ultimate bearing capacity of the members show a significant downward trend.(3)On the basis of the existing formulas for calculating the ultimate bearing capacity of buckling,the concept of local and global correlation stability coefficient is proposed.Based on the multi parameter regression analysis,the relationship between the coefficient and flange width-thickness ratio,web thickness ratio and slenderness ratio is established.Then the existing formula is modified and compared with the finite element analysis results.It is proved that the modified formula can be applied to the calculation of the ultimate buckling capacity of the cross section of the axial compression column with high-thickness ratio.The results will provide theoretical support for the design and analysis of high strength steel structures in china.