Unified Span-to-Depth Ratio Equation for Nonprestressed Concrete Beams and Slabs

A single span-to-depth ratio function is proposed for control of deflections in one- and two-way concrete construction. The equation can be applied to one-way slabs, beams, flat plates, flat slabs, and edge-supported two-way slabs. Effects of cracking, time-dependent deformation, boundary conditions, applied loading, and target deflection-to-span ratio are taken into account. Design examples are provided to demonstrate the application of the proposed equation for proportioning members for deflection control.