Ductile design and testing of steel frames having moveable bracing infills

This paper experimentally investigates the cyclic inelastic performance of concentrically braced frames (CBF) with and without cold formed steel stud (CFSS) infills designed to laterally restrain braces and delay their buckling. Specimens have either diagonal tube or solid bar braces with and without CFSS and U brackets providing out-of-plane and in-plane buckling restraint. Four, 1/2-scale specimens (boundary frame and infill members and their connections) were ductile designed and tested. Behavioral characteristics of the specimens are quantified with an emphasis on hysteretic energy dissipation. Experimental results show that, at the same ductility levels, the cumulative energy dissipation of braced frames can be significantly increased when CFSS members are used to laterally restrain the braces against buckling. However, when tubular cross sections are used for braces, local buckling led to a reduced fracture life compared to the case without CFSS members.