Characterization of the elevated temperature behaviour of demountable shear connectors in steel-concrete composite beams through push-out tests

Abstract

Demountable shear connectors are a key component of reusable structural systems. The intention behind the development of these systems is substituting, or at least providing a valid alternative to the widely utilized beam-to-slab connection via shear studs, which are welded to the flange of the steel profile and embedded in the concrete slab, therefore eliminating the possibility for the slabs to be reused in a new structure. To ensure that these demountable connectors are a valid option in practice, it is necessary to analyse them under different actions, including the fire situation. This is the primary purpose of the experimental campaign presented in this investigation, where a series of push-out tests at elevated temperatures are performed to extend the previously available results at ambient temperature, as a response for the need of characterization of the behaviour of the proposed demountable shear connectors in the fire situation, thus facilitating their applicability in the construction sector. This study shows how temperature affects the shear resistance of the connectors, their ductility, and the slip resistance. The available design provisions in EN 1993–1-8 and the reduction factors in Annex D of EN 1993–1-2 for bolts loaded in shear are tentatively applied to high temperatures, as a way to assess their validity for fire design.