The method of limit state design, developed in the USSR and based on research led by Professor N.S.
The loads to which a structure will be subjected must be estimated, sizes of members to check must be chosen and design criteria must be selected.
In contrast, the ULS is not a physical situation but rather an agreed computational condition that must be fulfilled, among other additional criteria, in order to comply with the engineering demands for strength and stability under design loads.
Complying with the design criteria of the ULS is considered as the minimum requirement (among other additional demands) to provide the proper structural safety.
the structural behavior complies with, and does not exceed, the SLS design criteria values, specified in the relevant standard in force.
In view of non-structural issues it might also involve limits applied to acoustics and heat transmission that might also affect the structural design.
As a result, most modern buildings are designed in accordance with a code which is based on limit state theory.
Australia, Canada, China, France, Indonesia, and New Zealand (among many others) utilise limit state theory in the development of their design codes.
In the purest sense, it is now considered inappropriate to discuss safety factors when working with LSD, as there are concerns that this may lead to confusion.
Previously, it has been shown that the LRFD and ASD can produce significantly different designs of steel gable frames.
[3] There are few situations where ASD produces significantly lighter weight steel gable frame designs.