Abstract
The objectives of this paper are to understand the plastic behavior of cold formed members and to establish the evaluating method of deformation capacity and ultimate strength for the antiseismic design of these steel structures. In the course of this reserch, a total of 25 specimens of cold formed steel beams and 8 specimens of these protal frames including of the braced frame are tested. The test parameters of beam specimens are the shapes of cross section, slenderness ratio and moment distributions. The parameters of frame tests are the cross section of colum members, the details of connection and the boundary condition of base. Experimental results are discussed comparing with that of the heavy steel members and frames. On the cold formed steel members, the ultimate strength can not exceed full plastic moment M_p and local bucking occures at the early stage. The critical buckling stress are not over the yield stress point. From the above reasons, the deformation angle θ_y at the yield moment M_y are introduced for the base evaluated value. The load deflection capacities enough to insure the safety of structures on the antiseismic design. On these structures, the stiffness of connections have not bad effects on deformation capacity. Finally, from these experimental results, the new evaluated method of deformation capacity and ultimate strength for the antiseismic design of these steel structures that have large wide-thickness ratio are proposed.
