Concrete-Steel Interfacial Bond Strength in Composite Flooring: Shoring and Form Removal

Abstract

Composite floor systems, constructed with cold-rolled corrugated steel decking covered with concrete, are a common design scenario in current construction practice. The limit state that most frequently controls the design strength of such composite floor systems in the finished structure centers on a breakdown in the interfacial bond strength between steel and concrete due to horizontal shear stresses developed during flexure. It is assumed in current practice that this same interfacial bond strength limit state governs during construction of the floor system as well. Existing design guides base recommendations regarding the timing of shoring removal, during the construction phase, on concrete compression strength alone. Such an approach is philosophically consistent with development length equations from reinforced concrete design, wherein it is assumed that the interfacial bond strength between rebar and the surrounding concrete is related to