Effect of Confinement on Cross-Sectional Performance of Steel–Concrete Composite Beams with Solid and Cellular Steel Sections

The aim of this study was to compare the moment–curvature (M–Φ) characteristics of a solid composite section (SCS) and cellular composite section (CCS) of a beam under a sagging moment. The strip method, based on the principles of fundamental mechanics that consider linear strain variation across composite sections, was used to determine M–Φ. It was first developed for SCS for different parameters, i.e. the grade of concrete, unconfined and confinement strength of concrete, and effective width of a concrete slab, and then extended for CCS. CCS had a 50% depth enhancement over the steel section of SCS. Full interaction between the steel beam and the concrete slab up to the failure of the slab was assumed in the analysis. According to the M–Φ analysis, CCS enhances the ultimate moment capacity and ultimate curvature for unconfined and confined concrete. Concrete confinement for CCS effectively boosted steel material utilization and resulted in higher curvature ductility before failure. The high concrete strength and wider effective flange width of the slab resulted in high ultimate moment capacity and ultimate curvature for SCS and CCS for unconfined and confined concrete.