Novel cold-formed steel elements for seismic applications

摘要

Novel cold-formed steel (CFS) elements are investigated in this paper for seismic resistant multi-storey moment frames. Premature local buckling and low out-of-plane stiffness are known as the main structural deficiencies of CFS sections with thin-walled elements. These lead to low energy dissipation capacity of the structures made up of CFS sections as the main load bearing members in seismic events. In order to improve the energy dissipation capacity of CFS members, an innovative CFS beam section with curved flanges is developed by numerical FE analysis and experimental work. A web bolted through plate CFS beam-column connection is used to limit out-of-plane actions in transferring the beam forces to column faces. This type of connection, however, produces premature web buckling and needs to be strengthened by a combination of vertical and horizontal out-of-plane stiffeners. Six beam-column connection assemblies including different stiffener configurations were tested. It is shown that the ductility factor and the moment strength are increased by up to ～75% and ～35% respectively relative to the specimen without stiffener. Correspondingly, activation of connection slip leads to a highly stable hysteretic behaviour and a significant increase (up to ～240%) in the hysteretic energy dissipation capacity.