Elevated slabs made of hybrid reinforced concrete: Proposal of a new design approach in flexure

When designing fiber‐reinforced concrete (FRC) structures, one of the basic design issues is represented by the choice of a proper combination of fibers and conventional reinforcement that allows to obtain the best structural performance with the minimum amount of materials. The combination of rebars and fibers in the concrete matrix is generally known as Hybrid Reinforced Concrete (HRC). HRC represents a feasible solution in many structures; among these, slabs are gaining an increasing interest among practitioners. In fact, slabs are the most widespread structural elements in common practice as they are typically used to construct slabs on ground (industrial floors or foundations), slabs on piles (foundations) or elevated slabs. This paper focuses on the flexural design of FRC elevated slabs by using the most recent design provisions reported in the fib Model Code 2010. A simplified design procedure based on a consolidated design practice is proposed. Emphasis is given to the use of HRC to minimize the total reinforcement (fibers + rebars) in order to get practical and economic advantages during construction (ie, construction time and costs reduction). In more detail, a procedure for proportioning the hybrid reinforcement and then verifying the structural safety will be presented and discussed. Numerical nonlinear finite element analyses will be carried out to assess the effectiveness of the proposed design method.