Study On Buckling Behavior Of Q690 High Strength Steel I-section Columns

With the development of steel structure and the improvement of construction technology in recent years,more and more HSS?high-strength steel?is applied in structure engineering.Compared with carbon steel,the chemistry composite and,mechanical properties and manufacturing process of HSS are quite different.At present,there is no relevant standards applicable to design of HSS in China.Therefore,in this paper,the effect of different parameters on buckling behavior of weld I-section of Q690CFD HSS under axial compression and compression bending was studied and provided suggestions for designing.The main research contents are as follow:1.Established the FEM?finite element model?,considering effect of the combination of geometry and material nonlinearity,initial defects and residual stress.The accuracy of the FEM was first validated by comparing with test data.Then the parametric studied was carried out to investigate the effect of the flange width thickness ratio,web height thickness ratio,initial defect and residual stress on the buckling capacity of members.2.By comparing the results of FEM,it was found that the width thickness ratio of flange,the height thickness ratio of web,the initial defects and residual stress have similar effects on the buckling capacity of two different types of members.With the increase of the ratio of flange width to thickness,the dimensionless ultimate bearing capacity of the member increases to some extent;with the increase of the ratio of web height to thickness,the dimensionless ultimate bearing capacity of the member decreases;With the increase of initial imperfection and residual stress,the dimensionless ultimate bearing capacity of members is weakened to some extent,especially for the compression bending members,the weakening degree of load eccentricity is higher than that of the initial bending.3.By comparing the results of FEM with design codes at home and abroad,it is found that Q690 high-strength steel axial compression members and compression bending members have different predictions on the design of column bearing capacity in different codes,which can provide certain reference for the design and analysis of high-strength steel structure in China.For axial compression members,due to the effects of different initial defects and residual stress,the design of column bearing capacity can refer to class a₀ and class b curves in EC3,class a and class b curves in the current Chinese code for design of steel structures,and class c curves in Appendix A for compression bending members.However,in the current code for design of steel structures in China,the design of bearing capacity of high-strength steel bending members is more conservative,and its applicability needs to be further explored.