The Theoretical And Testing Research On The Buckling Behaviors Of Tapered H-Section Steel Column With Thin Web

With the increasing widely application of portal frame structure with tapered members, it also appears more important for study on its stability. For the economical purpose, tapered H-section members are frequently used in steel portal frame structure. Large width-thickness ratio is generally applied in the type of members, so the influencing factors of interactive buckling are very complex. Howerver, at present, many researches are focused on how the tapered members work when subjected to monotonic static loading. There are no guidelines to the seismic design of steel portal frame structure. Therefore it has both academic significance and practical value for the research on the buckling behaviors of tapered H-section steel columns under monotonic static loading or cyclic loading.Above all, based on stability theory and nonlinear finite element (FE) method, ANSYS finite element models (FEM) are presented, which introduce shell181 and take geometric and material nonlinear into account. In the process of FE analysis, influence of initial imperfection can be conveniently considered.Interactive buckling whole process parameter analysis of tapered H-section steel columns under monotonic static loading has been performed. According to load-displacement curves, elastic load-carrying capacity, ultimate load-carrying capacity , the deformation of members, the development of plasticity etc. calculated by ANSYS, influence of some parameters like web slenderness ration, flange slenderness ratio, web tapering ratio and member slenderness ratio on the buckling behaviors of members has been analyzed under pressure or combined pressure and moment. Then according to numerical analysis results, correlative formula has been adjusted properly for performing elasto-plastic design and predigesting method of efficient width. Moreover correlative curves for axial force and bending moment have been drawn, which are valuable for engineering design. Finally, Elastic load-carrying capacity or ultimate load-carrying capacity and web height relative equation for uniformed section members is fitted. Based on the principle of equal load-carrying capacity, web height for tapered section members corresponded elastic or ultimate load-carrying capacity is sought. It has been proved to be proper relatively that web slenderness ratio in big end represents web slenderness ratio of tapered H-section steel columns.Seven specimens of tapered H-section steel columns have been tested under cyclic loading, in which, testing phenomenon, hysteresis loop, local buckling, energy dissipation, skeleton curve, displacement ductility coefficient, ultimate load-carrying capacity are focused on. According to the test results, influence of some parameters like pressure, web and flange slenderness ratio, web tapering ratio and initial imperfection etc. on the buckling behaviors of members has been analyzed. Failure mechanism has been analyzed. Some conclusions and suggestions are given.In the end, the buckling behaviors of tapered H-section steel columns under cyclic loading are analyzed mainly. On the principle of optimizing tapering ratio, members of different web slenderness ratio are discussed from several views on hysteresis curves and local buckling etc. Considering combined stable load-carrying capacity and ductility, the limit of web slenderness ratio has presented.