Full-Scale Floor System Testing for Future Hot-Rolled Asymmetric Steel I-Beams

The presented study conveys the initial full-scale experimental study for future hot-rolled asymmetric steel I-beams, termed A-shapes. The primary use for these beams is residential building floor systems. Current systems commonly utilize concrete solutions, which achieve a shallow depth for optimal floor-to-floor heights. However, these floor systems are relatively slow to construct because of the amount of formwork, rebar and post-tensioning placement, and shoring needed. The shallow-depth steel-concrete floor system concept explored in this research aims to improve the speed and efficiency of residential building construction. This increase in speed is achieved through hot-rolled steel A-shapes, which reduce the fabrication time for beam production. These steel shapes have a wide bottom flange that can support precast concrete panels or deep metal decking. Therefore, a relatively easy to assemble shallow-depth system can be achieved. The research study presented herein includes the experimental feasibility testing of a full-scale shallow-depth steel-concrete floor system to further the knowledge of A-shape performance in such systems. The floor system concept evaluated consisted of three steel A-shapes, precast hollow-core concrete panels, and a cast-in-place concrete topping slab. The testing involved taking measurements during construction, service live loading, and loading of the system to failure. The major unknowns were constructability, stability during construction, live load performance, and composite behavior. This experiment revealed that the system was constructed easily and rapidly and also remained stable during construction. The system performed well under service live load, experiencing deflections equivalent to $L/\mathrm{3,000}$. The system failed due to the bond breaking between the concrete and steel, going noncomposite after experiencing partially composite behavior. This occurred at an actuator load equivalent to five times the design service live load. All of this indicates that the floor system concept using A-shapes is a legitimate path forward to faster construction of residential facilities. This validates the need for the research toward standardized A-shapes in the United States.