Finite element analysis of hollow structural sections subject to torsion and combined loading

The reliability of steel structures is governed by design codes which may vary between countries. These codes may stipulate factors of safety, quality, and loading conditions. The approved steel design codes ensure each structure is designed with the same quality, recommended loading conditions, and safety standards for the design life of the structure. In Canada, steel structures are governed by the Canadian Standards Association (CSA) and designed to CAN/CSA S16-19 – Design of Steel Structures [1]. In the United States, steel structures are governed by the American Institute of Steel Construction (AISC) and designed to ANSI/AISC 360-16 – Specification for Structural Steel Buildings [2]. Both Canada and the United States have similar design principles included in their structural design codes. Therefore, the Canadian steel code and the load-resistant factored design sections of the American steel code are almost interchangeable. From the literature review comparing the most current Canadian and American principle clauses, it was identified ANSI/AISC 360-16 [2] provides mathematical equations for checking HSS in torsion and combined loading while CAN/CSA S16-19 [1] advises the user to complete an elastic analysis for verification. While the approach of completing a finite element analysis to the torsion stress is a very precise method, having the option to use theoretical formulas in accordance with limit state design to analyze this condition could be beneficial to practicing engineers. This thesis concentrates on strength verification of the American torsional clause using non-linear FEA techniques with calculated section capacities to determine if the clause can be a potential recommended method of torsion loading assessment. The objective of this work is to develop a practical method of evaluating hollow structural sections subject to torsion and combined loading in Canada. From the research performed, conclusions are made based on the results of the analysis. Recommendations are provided according to the application of the ANSI/AISC 360-16 [2] torsion clause along with the additional research required for validation as an approved design approach in Canada