Axial response of cold-formed steel bracing members with holes

Steel bracing systems are usually introduced to assure the structural stability and seismic resistance of steel storage pallet racks, whose height over the last years has increased more and more to improve warehouse efficiency. In the present paper, the axial response, under monotonic and cyclic load, of perforated cold-formed steel diagonals of concentric bracing systems is investigated through experimental tests. To satisfy the design and detailing rules required by the capacity design approach, such as the ratio between overstrength coefficients and the value of the non-dimensional slenderness, tested diagonals are equipped with additional holes at one end. Results of monotonic tests, under compression and tensile load, provide useful information about the influence of the number and shape of holes on the ultimate strength, ductility and buckling load of bracings. Cyclic tests highlight how the member slenderness and the class of its cross-section affect hysteresis loops and energy dissipation. Finally, some novel considerations are presented concerning the influence of the shape, dimensions and distance of additional holes, in addition to member geometrical features like the cross-section class, on the cyclic response of tested members. In the framework of the “Design Assisted by Testing”, results could be adopted for the capacity design of perforated concentric cold formed diagonal bracings as those adopted in steel storage pallet racks.