The Building Structural Standard defines a two-way slab system as a concrete slab system in which two rebars are arranged in two directions regardless of the presence or absence of a beam that transmits a load to a column'. Also, in ACI 318, this is expressed as ‘slab systems reinforce flexure in more than one direction, with or without beams between supports’. Therefore, a two-way slab system refers to a slab system in which reinforcing bars are arranged for bending in two or more directions regardless of the presence or absence of beams in columnar rows'. Typical types of two-way slab systems commonly used today include two-way slabs with beams, flat plates, flat slabs, and waffle slabs.

Figure1. Typical Types of 2-Way Slab