Development and evaluation of demountable shear connectors for steel–concrete composite structures

Demountable steel–concrete composite structures, utilised in sustainable building construction, incorporate demountable structural elements and shear connectors designed for reuse, aligning with the principles of the circular economy. This research and development project focuses on designing a demountable steel–concrete composite slab system for building applications, aiming to establish a design method based on Eurocode standards. The proposed structural solution comprises steel beams and precast reinforced concrete panels, featuring steel assemblies, mortar filling and embedded bolts as demountable shear connectors. A push-out experimental programme was conducted and extended by numerical studies. The results indicate that the shear connection demonstrates a suitable performance with adequate stiffness, resistance and ductility. The material properties of the concrete and mortar filling, particularly in the region surrounding the shear connector, significantly influence structural behaviour. The numerical model that is developed accurately represents real behaviour, facilitating a numerical parametric analysis of key parameters, including bolt grade, concrete grade, bolt position within the holes and panel thickness. Based on these results, a proposed structural solution has been developed and optimised, with mortar filling playing a crucial role in improving bolt hole clearance and force distribution. This updated solution has been used to design full-scale composite beam specimens for testing in the next research phase.