Numerical Analysis For The Hysteretic Behavior Of Cold-Formed Thin-Wall Steel Members Under Cyclic Uniaxial Loading

All kinds of economical cross-section configurations of the cold-formed steel (CFS) members can be produced by cold-forming operations, and consequently favorable section shape can be obtained. Besides, CFS members can be prone to facture, transport, install and industrialize. At present, CFS members have been widely utilized as principle structural members in low-rise light-gauge steel framed residences. However, research on CFS members is mainly focused on the range of elastic and static performance, and the post-buckling hysteretic behavior of CFS members has not been researched deep. Consequently, the current code—Technical Code of Cold-Formed Thin-Wall Steel Structures (GB50018-2002) still do not put forward the explicit design standard for aseismatic design of light steel structure. Because many areas in our country are required to be seismic fortified, and the application range of the light-gauge steel framed residences is very extensive, in order to explore the feasibility of light-gauge steel framed residences in seismic fortified areas, the researches for the hysteretic behavior of CFS members has great technical and economic significance.As we all know, it's necessary to make research by experiment. But there are some limitations in experimental investigation. With rapidly developing of finite element method and electronic computer technology, compared with physical experiments, the finite element method analysis is not only relatively more convenient and economical, but also can obtain quite accurate results. So using finite element method to study the hysteretic behavior of CFS members is necessary before making research by experiment.Herein, the hysteretic behavior of CFS members under cyclic uniaxial loading is numerically simulated by the finite element method. Through the finite element nonlinear analysis program ABAQUS V6.4-1, this paper uses S9R5 thin shell element and the linear kinematic hardening model for simulating geometric and material nonlinearities and Bauschinger effect, strain hardening and intensity increase at corner zone to establish the finite element models of CFS members under cyclic uniaxial loading, and utilizes existing theory and experiment results to verify the validity of the finite element models simulating the performance of large deflection and elasto-plastic, buckling and post-buckling of shell and C-section steel members under monotonic uniaxial loading and box-section steel members under cyclic uniaxial loading.In order to analyze the effects of different seismic loading on the hysteretic behavior of CFS members, the cyclic loading modes corresponding to different seismic loading are presentedto reflect different seismic characteristics. Subsequently, the effects of the cyclic loading modes and width-to-thickness ratio on the hysteretic behavior of CFS members are analyzed by energy dissipation ratio and energy dissipation per volume. Consequently some significative conclusions are drawn.In order to look for configurations of cross-sections with preferable aseismatic performance, some finite element models for analyzing hysteretic behavior of channel, C-section and intermediate V- or dovetail-stiffeners C-section CFS members under cyclic uniaxial loading are established. Subsequently, the effects of lipped plates and intermediate stiffeners on the hysteretic behavior of CFS members are analyzed by energy dissipation ratio, energy dissipation per volume, intensity and ductility, etc.The above analytical results show that CFS members may have preferable aseismatic performance as long as its width-to-thickness ratio can be controlled in certain range by some measures, which will lay the foundation for promoting the application of the CFS members in light-gauge steel framed residences in seismic fortified areas and farther research.