A new FRC solution for a partially prefabricated industrial deck

A new prefabricated deck is introduced in an industrial building to propose a viable alternative to the classical TT deck with a R/C top slab cast in place. The solution is characterized by a bearing capacity of 10 kN/m2, a main span of 14 m or more, an adjustable spacing in the orthogonal direction, FRC plates simply supported on the prestressed beams used as predalles, 4 cm thick, and a FRC top slab cast-in-place, 8 cm thick designed according to a continuous slab resting on the simply-supported beams. The proposed deck is a structural solution that tries to fit different issues like construction speed, transport cost reduction, structural optimization, high fire resistance (R120) and quality performance. All elements are made from SFRC with varying amounts of steel fibres. This paper firstly presents the concept of linearization to adequately select the necessary amount of fibres for the concrete mixtures used to cast the beams, predalles and top slab. Secondly, the results of the structural tests on four beams and two predalles are presented. The current design issues are highlighted and the validity of MC2010 equations in the case of multi-phase casting is verified. Two specific design situations for the precast beams are investigated: the shear behaviour at the support, where shear reinforcement is provided and prestressing action is only partially active, and far from the support, where only fibres are active, but the prestressing action is fully diffused and the web area is reduced due to holes allowing the passage of ducts and channels. Finally, a study is performed of the structural response of the composite system consisting of beams, predalles and a top slab cast-in-place.