Shear Capacity of Composite Girders with Corrugated Steel Webs under Fire Conditions

In this study, a thermomechanical coupled numerical model is developed to investigate the ultimate load-carrying capacity of composite girders with corrugated steel webs (CSWs) at ambient and elevated temperatures. The proposed model is validated against existing experimental results and subsequently applied to investigate the effects of key parameters such as concrete slab area, concrete strength, shear span-to-depth ratio, and degree of shear connection on the ultimate load-carrying capacity of composite girders with CSWs. Taking into account the temperature-induced strength degradation, shear buckling of the CSWs, and the shear contribution of concrete slabs, a comprehensive formula for assessing the shear capacity of composite girders with CSWs at ambient and elevated temperatures is proposed. The effectiveness of the proposed formula in evaluating the shear capacity of composite girders with CSWs is validated through comparison with both finite element (FE) analysis and experimental results. Meanwhile, an analytical bending–shear interaction model is established by evaluating the ultimate strength of composite girders with CSWs under bending and shear. The study demonstrates that the concrete slab contributes approximately 15%–37% of the total shear resistance, significantly enhancing the shear capacity of composite girders with CSWs. This finding challenges the conventional design assumption adopted in most current specifications, which neglects the shear contribution of concrete slabs. The proposed formula accurately evaluates the shear capacity of composite girders under various loading scenarios and elevated temperature conditions. The study provides a theoretical basis for designing the shear resistance of composite girders with CSWs under fire conditions, offering guidance for their application in practical engineering.