Experimental Program on Behavior of Concrete-Filled Steel Deck Composite Diaphragms

A limited amount of data exists on the cyclic behavior of concrete-filled steel deck diaphragms, and the few historical testing programs that have been conducted used specimens that may not be representative of modern floor assemblies typical in North America. As part of a larger research project, the Steel Diaphragm Innovation Initiative, an experimental program was conducted to fill critical knowledge gaps related to the behavior and design of concrete-filled steel deck diaphragms leading to a better understanding of the seismic performance of steel buildings utilizing these types of diaphragms. The experimental program included eight diaphragm specimens that were approximately 4 m by 5 m, tested in a cantilever test setup wherein one edge is restrained against translation while the opposing edge is subjected to an in-plane cyclic displacement history. Parameters that were varied included deck height (51 mm and 76 mm), concrete cover over the deck (51 mm to 115 mm), concrete type (normal weight and lightweight), configuration of perimeter headed shear studs, and the presence and amount of reinforcing steel. Specimen behavior was quantified including initial stiffness, peak shear strength, ductility, and energy dissipation and qualitatively connected to observed cracking and deformations. The results of this experimental program, combined with tests from the literature were used to develop proposed expressions for peak shear strength and initial stiffness. The proposed expressions reasonably capture the experimental results and are suitable for design.