Effect Of Local Buckling On Hysteretic Behavior Of H-Section Members Of Q690 High Strength Steel Columns

High-strength steel members have been widely used in engineering,especially in frame structures in recent years due to their advantages of lightweight and high material strength.Under the premise of ensuring the overall stability of the structure,H-section high-strength steel compression-flexure members are prone to local buckling under reciprocating horizontal load,resulting in structural failure.When the section is more slender,local buckling will be more likely to occur,resulting in serious degradation of bearing capacity and stiffness.In this paper,Q690 high-strength steel welded H-section members are taken as the research object,and the hysteresis performance of compression-flexure members around different axis under reciprocating horizontal load is studied.First,the cross-section classification criteria of the current specification are summarized,and the related research on the hysteretic behavior of high-strength steel members are reviewed,and the shortcomings of the existing research are summarized.Then,compression-flexure hysteresis tests are carried out on 8 Q690 high strength steel welded H-section members with different width-thickness ratios and axial load ratios,and the members are divided into two groups,bending around the strong axis and weak axis.The influences of flange width-thickness ratio,web width-thickness ratio and axial load ratio on the hysteresis performances of compression-flexure members bending around different axes are investigated.Various phenomena of the specimens were recorded in detail during the tests and the test data were analyzed in detail.The influence of the second-order bending moment on the hysteresis curves of the compression-flexure members bending around different principal axes was investigated.The result shows that the failure mode of the compression-flexure member around the strong axis was local buckling of the flange and the web at the column bottom,and the failure mode of the compression-flexure member around the weak axis was local buckling of the flange.When the ultimate bearing capacity of the specimen has reached plasticity,the specimen has a certain plastic rotation capacity.In this test,the width-thickness ratio of the flange and axial compression ratio have an important influence on the hysteretic capacity of the member.The influence of plates width-thickness ratio on the hysteretic curve,cross-sectional plastic development coefficient,ductility coefficient,skeleton curve and energy dissipation capacity of the specimen is analyzed.Then,the general finite element analysis software ABAQUS is used to establish the finite element analysis(FEA)model considering the initial geometric defects and residual stress and the FEA results are compared with the compression-flexure test results.The results show that the finite element model can well simulate the failure mode and the corresponding hysteresis curve of the specimen,and the correctness of the model is validated as the basis for the subsequent parameter analysis.Based on the validated finite element model,147 Q690 high strength steel H-section members bending around strong axis and 75 H-section members bending around weak axis with a large width-to-thickness ratio are analyzed.The influences of flange width-thickness ratio,web width-thickness ratio and axial load ratio on hysteretic behaviors are analyzed.The FEA results are used to fit the relevant formulas of plastic development coefficient and ultimate displacement angle.Finally,the research content is summarized and the next research direction is pointed out.