Sustainable composite beams with deconstructable bolted shear connectors

摘要

Composite structures using steel joists mechanically connected to concrete slabs serving asrnthe flooring and decking systems are commonly used in buildings and bridges respectively. The use of thernstate-of-art sustainable geopolymer concrete and innovative deconstructable pretensioned bolts under servicernloads in composite beam design can reduce CO_2 emission by enhancing the sustainability of, and recyclabilityrnin, the construction industry by enabling deconstructability. Most previous research has been conducted onrncomposite beams with welded shear studs with conventional concrete using ordinary Portland cement, withrnlimited studies on beams with pretensioned bolted shear connectors being reported. This paper describes thernresults of five preliminary push tests that have been conducted to establish the strength and stiffness characteristicsrnof pretensioned bolted shear connectors. The effects of the size of the clearance holes, the diameter of the boltsrnand the pretension force are also investigated. It is shown that the shear connectors can induce three types ofrnshear interaction along a beam: viz. a region of “full interaction”, a region of “zero interaction” and a regionrnof “partial interaction”, that are delineated by the shear flow force at the interface, by the coefficient of frictionrnat the interface and bolt pretension, and by the size of the clearance hole relative to the diameter of the bolt. Arnmechanics-based model that can capture the beam behaviour based on the push test results is described.