Sustainable Design of Deconstructable Steel-Concrete Composite Structures

Abstract

As attention is being focused increasingly towards minimising carbon emissions and enhancing the possibly of material recycling in the construction industry, traditional composite systems are recognised as being problematic on several counts. Composite action between the conventional concrete slab and steel beam is provided typically by stud shear connectors welded to the top flange of the steel beam, and the demolition of such members requires a considerable amount of time and energy, as well as being environmentally intrusive and creating much waste. In addition, existing composite systems mostly utilise conventional concrete made from ordinary Portland cement whose production is attributed to a large portion of carbon emissions worldwide. As an alternative, it is proposed that precast concrete slabs be attached to a steel frame with semi-rigid bolted connections using high-strength friction grip bolts as the elements to provide the shear connection. Moreover, the use of geopolymer concrete in the casting of the slabs eliminates the use of ordinary Portland cement entirely. The paper reports tests undertaken on full-scale beams and on full-scale joints in this sustainable and deconstructable system. This study shows that both the joints and beams demonstrate very significant ductility, with large rotations, deformations and interface slips being developed and sustained during the testing. © 2016 The Authors.