Sustainable steel-concrete composite beams with novel demountable shear connections under positive bending moments: Experimental behavior and analytical model

Sustainable structures or structural components as one of the frontiers in civil engineering can solve the problem of construction and demolition waste and also enhance the reuse of structural components at the end of their service life or after damage. In terms of sustainable assessment, steel-concrete composite beams with or without novel demountable shear connectors were performed in this work. Structural configuration and mechanical properties of proposed sustainable steel-concrete composite beams were firstly presented and then the nonlinear analysis of this composite beams using the Abaqus software was validated. Three specimens with different types of shear connectors were designed and tested under two-point loading to investigate the flexural behavior and deconstructability. Results from this research showed that these composite beams exhibited a flexure-shear or flexural behavior, presenting the typical failure modes of yielding of steel beam, slab concrete split or concrete crushing of plug. Compared to that of traditional composite beam with embedded welded bolts, specimens with demountable shear bolts and demountable shear connections experienced reduced initial flexural stiffness (about 29.8% and 37.2%), yield strength (by about 18.3% and 32.1%) and ultimate strength (about 12.9% and 24.9%) due to the relative slip between the steel beam and precast concrete slab, respectively. Whereas these of composite beams developed a better deformation capacity and ductility coefficient. Additionally, sustainable steel-concrete composite beam with demountable shear connections could easily allow for easy installment and disassemble to achieve the recycle of these structural members and also replacement with new plugs to permit a quick seismic rehabilitation after earthquake damage. Finally, some suggestions of this sustainable composite beam and demountable shear connections were proposed to provide references for the design in practice.