Proof of concept of a demountable steel-concrete flooring system

Abstract

Environmental concerns steerthe construction industry towards more sustainable developmentssuch asdemountable and reusablestructures. Composite structures are a frequent solution for multi-story buildings and bridges, however the use of welded shear connectors requires labour and energy intensive disassembly. Two bays of a demountable flooring systemfor a multi-storey car park building were erected in the laboratory. The flooring system consists of large prefabricated concrete decks connected to taperedsteelbeams. The feasibility of assembly and disassemblyof the flooring system was tested under laboratory condition. Shear interaction was achieved by an embedded bolt and coupler which areconnected to the top flange of the steel beam by an external injection bolt. Oversized holes are used in thetopflangeof the steel beamto accommodate fabricationand executiondeviationsandthedeformations occurringduring construction. Extensive imperfection measurements and finite element models were used to design the oversized hole diameter to 32 mm. Thehole clearance must be compensated either by pretensioning or injecting the bolt-to-hole clearance with an epoxy resinto enable instantaneous composite action underlive loads.Experimental injection of 150 injection bolts confirmsthat epoxyresin can reliably fill the hole clearance, and that the injectionprocess takes30 seconds per bolt.Various non-uniform shear connector arrangementswere considered to minimizeconstruction costs and maximize the speed of execution. The mechanical behaviour of the demountable composite beam was tested experimentally and numerically.