ACI 447R-18

This guide assists practitioners in understanding: 1) twisting moments in two-way slabs, when twisting moments are an essential consideration; 2) methods that can be used to account for twisting moments in design; and 3) the options available for each method of the various system geometries. Descriptions of twisting moments are provided theoretically and visually in the guide, and six methods of accounting for twisting moments in design are discussed. Applicability of the various methods is evaluated through a comparison of designs resulting from each method for a variety of two-way slab types and geometries. The theories described in the guide also apply to the design of two-way wall and two-way dome systems.