Permissible stress design
From Wikipedia, the free encyclopedia
Permissible stress design (in American construction more commonly called allowable stress design) is a design philosophy used by civil engineers. The designer ensures that the stresses developed in a structure due to service loads do not exceed the elastic limit. This limit is usually determined by ensuring that stresses remain within the limits through the use of factors of safety.
The permissible stress design approach has generally been replaced by limit state design (also known as ultimate stress design) as far as structural engineering is considered, except for some isolated cases.
In American construction allowable stress design has not yet been superseded by Limit state design except in the case of concrete, which changed from allowable stress to limit state design in the 1960s. Wood, Steel, and other materials are still frequently designed using allowable stress design, although Load and Resistance Factor Design does exist for these materials and is probably more commonly taught in the American University system.
