Hybrid seismic testing of cold-formed steel moment-resisting frames

The true seismic performance of three full-scale, 2·2 m high by 3·2 m long, cold-formed steel (CFS), moment-resisting frame structures is investigated for the first time in this paper. In general, shear wall type CFS structures have performed well during earthquake events in the past; however, portal frame CFS type structures have not been investigated to any great degree. Limited cyclic testing of CFS moment-resisting connections/frames has shown the connections/frames perform well. However, these cyclic tests do not take account of inertia forces of the framing structural system. The seismic performance of CFS portal frames was investigated for the first time under true seismic loading using the hybrid test method. Results show that the frames perform well and under extreme loading fail through local buckling of the column section at the column-to-haunch connection. This failure mechanism needs to be prevented as it does not align with the strong column–weak beam design philosophy.