Prefabricated Steel Stair Performance under Combined Seismic and Gravity Loads

Abstract

Tests were performed on full-size prefabricated steel stair assemblies to assess seismic interstory drift response combined with factored gravity loads. The stair assemblies were production-run units of a standard system and were designed for a typical steel frame building. Two different stair assembly units were tested: one with checker plate and one with concrete-filled pans. A loading system and testing protocol were developed to evaluate the seismic performance using seismic and gravity load combinations. Lateral drifts were imposed in both orthogonal stair directions followed by factored live and dead gravity loads. Imposed lateral drift placed high deformation demands on the stair-to-landing connections and overall performance is dependent on the deformability and endurance of these connections. Careful detailing, fabrication, and inspection of the stair-to-landing connections are required to ensure desired system performance.