Experimental study on the flexural behaviour of demountable steel-concrete composite beams at room temperature and under fire exposure

In a context driven by the urgent need to promote sustainability and circularity in the construction sector, the use of demountable shear connectors in steel-concrete composite beams has a potential to make a significant contribution to reducing the carbon footprint, helping in the management of waste generated in the deconstruction stage through the “Design for Disassembly” concept. To ensure the viability of these shear connectors in practice, it is essential to understand their mechanical behaviour under various loading situations. This paper presents the outcomes of an experimental campaign comprising a series of beam tests conducted under both room and elevated temperature conditions. The results of the tests showed that, during a fire - provided that suitable protection is used for the steel beam -, the shear connectors retain their mechanical contribution and composite action between the steel beam and concrete slab is still active along fire exposure, thereby enhancing the flexural capacity of the beam. The findings from this investigation ensure the structural efficiency of demountable steel-concrete composite beams under both fire and ambient conditions, along with their alignment with the circular economy principles. This study sets the ground to facilitate the practical application of demountable steel-concrete composite beams in the construction sector. • Four bending tests on demountable steel-concrete composite beams were reported. • Two types of shear connectors were studied, showing good mechanical performance. • The demountable composite beams demonstrated a suitable fire performance. • A fire protection system was devised to meet a standard fire resistance R90.