Behavior of Roof Deck Diaphragms under Quasistatic Cyclic Loading

A series of 18 large-scale tests was carried out on corrugated cold-formed steel deck diaphragms for single-story buildings to investigate the diaphragm’s ability to function as the main source for absorbing earthquake induced energy through inelastic behavior. Tests were performed using a cantilever type configuration for the test setup, in which the steel deck was laid in a horizontal plane. Diaphragm assemblies made with 0.76 and 0.91 mm thick metal deck sheets and with nine combinations of deck-to-frame and deck-to-deck (side lap) fasteners were tested. For each fastening combination, two tests were conducted: monotonic and quasistatic cyclic. Both the strength and failure modes under quasistatic cyclic loading are different from those under monotonic loading. Test results indicate that diaphragms with welded deck-to-frame fasteners without washers have limited ductility and cannot sustain cyclic loading at relatively large displacement amplitudes. The use of mechanical and welded-with-washer deck-to-frame fasteners enhances the strength, ductility and energy dissipation characteristics of the diaphragm considerably.