Cyclic behavior of cold formed steel frames in-filled with styrene concrete

Light Steel Frame (LSF) systems are increasingly used as sustainable design solutions in modern construction. Using light weight concrete as infill material in LSF systems offers several advantages such as increased integrity, strength, ductility and fire resistance, while it also prevents premature local buckling failure modes. This research investigates the application of Styrene Concrete (SC) as light weight infill materials in LSF panels. Five full-scale LSF walls are examined to study the efficiency of using SC light weight infill material in improving the cyclic behavior of LSF panels. The specimens are designed to assess the effects of infill material as well as using strap bracing, hobnail and hole on the studs. The key seismic performance parameters including failure mode, load-bearing capacity, lateral stiffness, ductility, stiffness deterioration and energy dissipation capacity are obtained for each case. The experimental results demonstrate that the application of nonstructural lightweight concrete as infill material in LSF shear walls has significant positive effects on their seismic performance by postponing the buckling of the steel frame members and changing the dominant brittle failure to a ductile failure mode. The interaction between LSF members and SC infill material could also considerably improve the lateral performance of the frame system. It is shown that adding the hobnails to the vertical studs increased the lateral stiffness and resistance of the frames by 45% and 28%, respectively. While the presence of a hole in the studs had little effect on the lateral resistance of the wall, it increased the energy dissipation capacity and ductility of the system by up to 18% and 6%, respectively.