Structural Performance of Cold-formed Steel Face-to-face and Back-to-back Beams

The behavior of eight Cold-Formed Steel (CFS) beams was numerically and experimentally investigated. Each beam was built by assembling two single CFS channel sections from the same CFS sheet with or without intermediate web stiffeners (discontinuous inclined stiffeners; triangular, trapezoidal, and discontinuous linear stiffeners) back-to-back at the web or face-to-face at the flange using screws. The moment capacities of the face-to-face and the back-to-back specimens were determined via four-point and three-point bending tests, respectively. Finite element (FE) models were employed, and their results were validated using the test outcomes. The models predicted well the performance of CFS built-up beams with or without web stiffeners. For both the face-to-face and back-to-back beams, the beam with a triangular stiffener had the highest capacity and that with a discontinuous linear web stiffener had the largest ductility. This study was extended by a parametric study that included 24 beams using the validated model to investigate the effect of stiffeners, whether for web or flange on the behavior of CFS beams under various failure modes.