Plastic resistance to sagging bending of filler beam decks: Extension to S500 grade and steel fibre reinforced concrete

Filler beam decks are a traditional steel–concrete typology widely used in bridge construction and covered by the normative framework. The cross section is characterised by a deep‐lying neutral axis which calls for a restriction on the concrete cover thickness and eventually the application of an adjustment factor when applying plastic moment resistance. The present study assesses the use of the plastic resistance for conventional reinforced concrete with respect to the current limitations on the maximum concrete cover and steel grade. The application of steel fibre reinforced concrete is also assessed, an option which permits improvement of this typology at the serviceability and ultimate limit state. The superior concrete ductility in compression conferred by the fibres permits to eliminate the risk of concrete crushing in the concrete cover. This study conducts therefore some practical proposals for extending the current design method for filler beam decks concerning the material range and geometrical boundaries.