Seismic response of sheathed cold-formed steel structures under catastrophic events

The paper focuses on the behaviour evaluation of sheathed Cold-Formed Steel Structures (SCFS). Basically, if Cold-Formed Steel (CFS) structures are designed according to the "sheathing-design" methodology, then the seismic behaviour of shear walls is strongly influenced by the sheathing-to-frame connections response, characterized by a remarkable nonlinear response and a strong pinching of hysteresis loops. Therefore, non-linear dynamic analysis using an ad hoc model of the hysteresis response of SCFS shear walls have been carried out. An extended number of wall configurations has been considered investigating several parameters such as sheathing panel typology, wall geometry, external screw spacing, seismic weight and soil type. Based on results of IDA, three behaviour factors have been defined, which take into account overstrength, ductility and both overstrength and ductility, respectively. A "multi-performance" approach has been proposed to evaluate the behavior factors considering the response of SCFS walls also in the case of catastrophic earthquakes.