Ledge behavior and strength of long-span L-shaped beams (original) (raw)

■ The experimental results demonstrate that increasing the global stress reduces ledge capacity, while the use of prestressing increases the capacity, as does concentrating the ledge reinforcement at the load location. L-shaped ledge beams are frequently used by the precast concrete industry to support floor systems such as double-tee beams. The ledges are typically subjected to heavy concentrated loads with eccentricity and must be carefully designed to effectively transfer these loads to the web of the beam. Generally, these ledges perform satisfactorily when designed by the procedure included in the seventh edition of the PCI Design Handbook: Precast and Prestressed Concrete, referred to as the PCI procedure in this paper. However, since 1985, several engineers and researchers have expressed concerns about the procedure because research findings indicate that the PCI procedure may overestimate the punching-shear failure load of the ledge.