Flexural behavior of cellular composite beams with full shear interaction under sagging moment

The current European Standard (EN 1994-1-1: Eurocode 4) put forth a reduction factor for Solid Composite Beam (SCB) with Class 1 and 2 sections for the design moment of resistance for sagging bending. This paper presents the analytical study on the behavior of Cellular Composite Beam (CCB) and proposes the reduction factor for the ultimate moment capacity of CCB sections. A moment-curvature program based on the strain compatibility method has been developed and used to examine the behavior of CCB made of S355, S460, and hybrid strength steel sections with different geometries. The program involves elastoplastic analysis since it is crucial to explore how the cellularity of the composite sections increases their curvature ductility, flexural resistance, and material utilization under high strain. The developed program has been validated against FE results, available test data, and ACB+ software solutions. A parametric study has been carried out to determine the effect of steel grade, concrete grade, effective width and depth of the slab, and varying sizes of a web opening on CCB sections. The Eurocode 4 design guidelines were used to determine the bending resistance of CCB for S355, S460, and hybrid-strength steel sections. The parametric study showed that high-strength concrete with a wider effective slab and enhanced depth sections with the lowest web opening causes CCB sections to have a higher ultimate moment and ultimate curvature. Comparing the hybrid CCB section to the regular and high-strength sections also showcases a significant enhancement in ductility and moment capacity.