Design of Shallow-Depth Floor Systems with Asymmetric Steel I-Beams

Abstract

Shallow-depth composite floor systems aim to improve building economy, speed, and efficiency. Currently, an array of proprietary systems is available that comprises asymmetric steel sections (I-beam or trapezoidal box) with a relatively wide bottom flange. This wide bottom flange facilitates the placement of decking or precast/prefabricated panels. These systems are fast to assemble compared to cast-in-place flat slab construction. However, extensive fabrication is typically required for the current steel sections. As a result, this paper presents a design methodology for shallow-depth systems utilizing conventional asymmetric steel I-beams (AIBs) that can be hot-rolled or built-up. The design methodology covers the limit states critical for construction in the noncomposite state and in-service as a composite system. The composite design presented is a lower-bound approach with no mechanical connectors. The horizontal shear transfer is through steel-concrete bond and friction, resulting in a partial composite design. This design methodology was developed through an experimental testing program on shallow-depth floor systems. The testing reduced the uncertainty of several design parameters and validated certain assumptions. Three main phases of testing were (1) an initial large-scale concept test, (2) nine composite beam tests, and (3) a full-scale system validation test. The critical findings of each phase are provided. Finally, design aids are presented to equip future engineers with resources to efficiently design shallow-depth floor systems.