Cyclic Lateral-Torsional Buckling Response of Cold-Formed Steel C-Section Joists

Design of cold-formed steel (CFS) structures subjected to lateral seismic forces traditionally relies on the cyclic strength of subassemblages such as strapped/sheathed shear walls. Little regard is paid to the behavior of the individual components, their contribution to the lateral resistance of CFS structures, or to the actual seismic behavior of the structure as a whole. Understanding the cyclic behavior at the individual component level is necessary to develop a toolbox of nonlinear elements capable of accurately and efficiently simulating the seismic behavior of the infinite number of possible configurations in cold-formed steel structures. This paper summarizes initial results from an experimental program designed to evaluate the flexural cyclic response of cold-formed steel C-shaped structural flexural members. A cyclic loading protocol is adapted for cold-formed steel members to evaluate the energy dissipation characteristics of members experiencing lateral-torsional buckling deformations. 

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