Flexural Behavior of New Demountable Steel–Concrete Composite Beam with Novel Demountable Connectors

This study proposes a novel type of demountable steel–concrete composite beam (the slab is connected to the steel beam by T-shaped shear connectors, TCBs) to address the limitations of traditional composite beams, including difficulties in disassembly and challenges in resource recycling. Finite element analysis was conducted to compare a TCB’s mechanical performance and failure modes with those of traditional bolt-connected steel–concrete composite beams (BCBs). The results show that, while the TCB exhibits reduced initial stiffness, it enhances mid-span deformation capacity, demonstrating superior ductility and a more uniform damage distribution. Furthermore, the influence of parameters such as concrete strength, bolt diameter, steel beam strength, and flange thickness on the flexural performance of the TCB was investigated. When the bolt diameter increases from 16 mm to 24 mm, the flexural capacity increases by 45.26% and the ductility increases by 63.3%. Enhanced steel beam strength led to a 55.17% increase in bearing capacity, while an increase in flange thickness by 3 mm contributed to a 24.8% improvement in load-bearing capacity. Additionally, the ultimate flexural moment resistance was calculated and verified based on the shear-resisting connection theory, with the computed results showing good agreement with the finite element analysis results. The average ratio of these values was 0.97, with a standard deviation of 0.06. The findings provide a theoretical basis for designing and engineering applications of demountable composite beams.

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