Behaviour of sustainable concrete-steel composite beams with bolted shear connectors

Traditional steel-concrete composite beams are known to exhibit excellent structural characteristics, in terms of their stiffness and strength, when compared with bare steel or reinforced concrete beams. However, within current paradigms of lowering carbon emissions and enhancing the possibly of material recycling, such traditional composite beams cannot be deconstructed easily and their elements are not recyclable because they rely on welded headed stud connectors that are encased within cast in situ concrete to achieve the necessary shear connection. In this paper, a three-dimensional finite element model is developed to investigate the structural behaviour of innovative composite beams with deconstructable post-installed friction-grip bolted shear connectors. For this system, precast concrete slabs are attached to a steel beam using tensioned high-strength friction-grip bolts in clearance holes as the elements to provide the shear connection. The precast slabs are made using geopolymer concrete in lieu of concrete made from ordinary Portland cement, whose manufacture is a major contributor to anthropogenic CO2 emissions worldwide, thereby enhancing the low-carbon attributes of the structural system. Non-linear continuum-based finite element models are developed and validated against the results of three full-scale laboratory tests of this innovative beam. Material non-linearities and the interaction of the structural components are included in the model.

Keywords:

Composite beams , Sustainable construction , Deconstructable , Friction-grip bolt , Finite element model