NUMERICAL ANALYSIS OF DELTA COMPOSITE BEAMS IN FIRE

Composite state-of- the-art decks include shallow floor systems such as the “slim floor” and the “slim deck”. One such type of floor, which has been manufactured recently and is of particular interest to the industry, consists of DELTA steel beams partially encased in concrete. Investigating the behaviour of DELTA composite beams under elevated temperatures is crucial in determining their fire resistance and evaluating their overall performance in contemporary construction. Even though the manufacturing company provides fire resistances for DELTA composite beams based on experimental testing, their response to elevated temperature effects remains up to date neither well documented nor clearly understood. This paper presents a detailed numerical simulation of such beams exposed to fire, via the finite element method. Material modelling followed the specifications of the Eurocodes. Eight coupled thermal-structural analyses were carried out in total. Theparametric analyses involved four different variations of the “shortest” cross-section specified by the manufacturer. Analysis results showed that such beams experience severe temperature gradients when exposed to fire, because the lower flange remains unprotected, in contrast to the concrete encased part of the cross-section. Deflection governed the failure of the beams in all cases. Results also suggest that simulated beams sustained the applied load for approximately 60min of exposure to the standard fire.