Sustainable Composite Beam Behaviour with Deconstructable Bolted Shear Connectors

Composite structures using steel joists mechanically connected to concrete slabs serving as the flooring and decking systems are commonly used in buildings and bridges, respectively. The use of the state-of-art precast geopolymer concrete slabs coupled with innovative deconstructable pretensioned bolted shear connectors under service loads in a life-cycle composite beam design can reduce CO₂ emissions, thereby enhancing the sustainability in and recyclability of the construction industry. Most previous research has been conducted on composite beams with welded shear studs that cannot be deconstructed easily. A number of push tests are reported in the current study to establish the interface strength and stiffness characteristics of the bolted shear connectors. The application of the push test data in predicting complex full-scale composite beam behaviour with three distinctive regions that are delineated by the shear flow force at the interface, by the coefficient of friction at the interface and bolt pretension, and by the size of the clearance hole relative to the diameter of the bolt is explained. An initial theoretical investigation based on a simple mechanics-based “full-zero-full” shear interaction mechanism is presented and discussed.