Assessment of Design Provisions for Open I-Section under Combined Flexure and Torsion

Abstract

In civil structures, the members often encounter a combined loading of flexure and torsion, which has a strong influence on the members’ behavior and capacity, especially for those beam sections with relatively weak torsional resistance, such as the commonly used I-shaped sections. To ensure both the safety and the economy of design result, the validity of different design methods for combined flexure and torsion should be investigated before any practical applications are attempted. In this thesis, finite Element (FE) models are developed and verified using theoretical analysis and experimental results in the literature. The influence of a number of key parameters on the behavior, ultimate strength, and serviceability of representative I-shaped beam members are investigated via the finite element method FEM approach. The current main design methods for combined flexure and torsion are also evaluated based on the FE simulation results. Suggestions are made regarding the applicability of the design methods studied in this thesis for the ultimate strength prediction of I-shaped beam members.