Study on seismic behavior of double leg C-type cold-formed thin-walled steel frame.

The cold-formed steel (CFS) frame has the advantages of high strength, light weight, high construction efficiency, so it has been widely applied in building structures. However, the research on the seismic performance of multistory frames, especially those with braces, is rarely reported, the design method is also incomplete. In view of this, a pseudo static experiment of a three story double leg C-section CFS frame with brace is carried out. The bearing capacity, ductility, stiffness degradation and energy dissipation performance of the specimens are studied. The finite element analysis (FEA) method is used to simulate the failure process of the CFS frame and the design suggestions are proposed. The experiment result show that the failure process of the cold-formed thin-walled frame without braces has satisfactory ductility and energy dissipation performance; For framed CFS frame, the lateral stiffness and bearing capacity of the CFS frame increases, but the ductility decreases. Replacing double angle steel brace by steel plate strip brace can improving the seismic performance of structures, but there is an optimal width thickness ratio of steel plate strip. In this paper, the optimal width thickness ratio of brace is 5.0. When the design suggestions proposed in this paper are met, the CFS frame can achieve "strong structure, weak brace", so as to improve the seismic performance of the frame. • A double leg C-type cold-formed thin-walled steel frame with backing plate is proposed. • The seismic performance of a new cold-formed thin-walled steel frame is tested and the role of bracing is analyzed. • The simplified analysis model of the new frame is given. • Through finite element simulation, the optimization design method and key parameters of the bracing are given. [ABSTRACT FROM AUTHOR]