Experimental-numerical assessment of laterally-loaded CFS frames with steel sheathing and K-shaped braces

Abstract

In this study, the behavior of cold-form steel (CFS) frames equipped with various configurations of steel sheathing, and K-shaped braces are experimentally investigated. Low lateral resistance is a major problem with the CFS shear walls. Despite their advantages, such as being lightweight, ease of fabrication, and an environmentally friendly system, their lack of adequate lateral strength prevents engineers from widely using them, especially in areas with medium to high seismicity or mid-rise buildings. In this regard, a total of seven full-scale specimens with different configurations of steel sheathing and k-braced, with and without cladding, were tested to investigate their seismic behavior. The effect of gravity loading on the lateral resistance of the CFS frames was tested using three specimens. The gravity loadings of the CFS specimens were determined assuming an ordinary two-story CFS frame building. The effect of different CFS frame configurations on the energy dissipation, secant stiffness, and ductility factor of those frames was evaluated. The failure modes observed in this study can be classified into brace connection failure, brace element failure, sheathing, and chord stud failure. Moreover, using a calibrated simplified nonlinear model, the seismic behavior of different CFS configurations under earthquake excitation was examined. Based on the obtained experimental and numerical results, it can be concluded that the proposed dual CFS frame and shear wall configuration has a better performance both in the cyclic test and the numerical studies compared to the CFS walls with steel sheathing or bracing alone.