Torsion in Closed Sections

Academic discussions of torsion in closed sections can be found in most textbooks on elasticity; however, there is a notable lack of literature containing an engineering approach to this subject. This may be due to the fact that, until recently, pipes were the only closed sections commonly used in engineered structures. With the increased use of welding, and with developments such as "orthotropic" steel bridge decks, closed sections will undoubtedly be encountered more frequently in engineering practice. This paper will discuss the analysis of torsion in closed sections from an engineering point of view. Emphasis is placed on the physical significance of equations, rather than exact theoretical proofs. It is hoped that this treatment will lead to a better understanding of the engineering aspects of the subject.