Design and Verification of Elevated Slabs Made with Hybrid Reinforced Concrete: Case Studies

The literature has recently reported many real applications with the use of Fiber Reinforced Concrete (FRC) for the construction of elevated slabs. Most of these case studies suggests the use of steel fibers as the only reinforcement in addition to the Anti-Progressive Collapse (APC) used to prevent brittle failure mechanisms. However, this reinforcement arrangement does not usually represent an optimized design solution as high amounts of fibers (Vf > 70 kg/m3) are often required for reaching the minimum capacity to resist design loads as well as to the internal actions due to restrained shrinkage. This paper focuses on the 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 described. The use of a properly designed combination of fibers and conventional reinforcement, referred to as Hybrid Reinforcement, is proposed. Different case studies taken from the literature are considered to prove the effectiveness of the proposed design approach.