Method of ratio of aci doc

Direct design method is an approximate method for analyzing slab systems in two directions requested only by gravity loads. because it is approximately procedure; the application of this method is limited to the slab systems that meet the limitations specified in article 13.6.1. systems slabs in two directions that do not satisfy these constraints should be analyzed by more accurate methods as the equivalent frame method specified in 13.7. in part 20 we present a discussion of the portico equivalent method; together with design examples.