| From the perspective of flexible design, the main differences between light steel structure and ordinary steel structure or heavy steel structure are that the light one bearing smaller vertical load and of the cross-section may carry out more when the area is the same for which causing larger bending load capacity and better cost-effectiveness. The potential development of panel post-buckling strength is greater in light steel structure than ordinary or heavy one because of its smaller vertical load from the point of plastic design.With the promotion of multi-storey steel structure in China in recent years, multi-storey steel frames are widely used in civil and public buildings such as dwelling structure because of the quality of light weight and high strength. However, there is no industry standard for light steel frame design, and most of the designs utilize Steel Structure Design Specification (GB 50017-2002), Technical Specification for Steel Structures of Tall Buildings (JGJ99-88) and Seismic Design of Buildings (GB 50011-2001) as references. Light Steel House Technical Regulations which has been examined and approved is also utilized as reference.The advantage of light steel frame and the mechanical properties of steel can not fully utilized that causing material wasted.In this paper, post-buckling strength is introduced into design of multi-storey light steel frame from the seismic aspect. Multi-storey light steel frame system with H-section column is studied. Based on the study on the limit of height-to-thickness ratio of H-section column web, the limit of width-to-thickness ratio of H-section column flange is discussed. An design example is calculated and analyzed. Evaluation for light steel frame design in actual project is obtained as references for seismic design of multi-storey light steel frame.The major parts of the text are as follows:The theroy of post-buckling of slab is introduced to give the surpport for the following research.The basic computational models of frame established by ANSYS are studied through Quasi-static simulation. Failure mode, hysteresis curve,skeleton curve and ductility of frame under different height-to-thickness ratio of H-section column web and width-to-thickness ratio of H-section column flange are compared. The limit ratio of width-to-thickness of H-section column flange is proposed prior to the limit ratio of height-to-thickness of H-section column web.A three-storey light steel frame with H section column is designed. The height-to-thickness ratio of column web and width-to-thickness ratio of column flange meet the research result in this paper but not meet that in existing norm.Firstly, the frame is caculated by STS and ETABS for elastic study under small earthquake. Secondly, the pushover static nonlinear analysis is taken on the frame by ETABS. The seismic capacity of the frame in large earthquake is assessed through analysis of the development process of plastic hinge.The example calculation can be concluded:The use post- buckling strength of light steel frame should be made according to the corresponding fortification intensity in design.When the fortification intensity is not greater than 7, the application of large column web thickness ratio can meet the seismic requirement and he economy can be reflected. When the fortification intensity is greater than 7, the thickness of flange must be thicken to use post- buckling strength of column web. It can be achieved from mechanical properties aspect but the overall economic point of view is irrational. Therefore, it is not suggested to use post- buckling strength of column in the high fortification intensity area. |
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