St Venant Torsion and Non-Uniform Torsion — Lesson 1

This lesson covers the concept of torsional buckling, a phenomenon where structural members deform by twisting or a combination of twisting and bending. It delves into the types of torsional buckling, namely torsional and torsional flexural buckling, and explains why thin-walled open sections are prone to this type of buckling. The lesson also discusses the conditions under which torsional flexural buckling occurs, such as when the shear centre and centroid do not coincide in an axially loaded member. It further elaborates on the concepts of St. Venant torsion (uniform torsion) and non-uniform torsion, providing mathematical expressions for each. The lesson concludes with an explanation of the strain energy stored when torsion is applied to a member.

Video Highlights

00:51 - Discussion on torsional buckling and torsional flexural buckling
03:54 - Discussion on torsional rigidity and its representation
08:30 - Explanation of warping torsion and St. Venant torsion
16:33 - Discussion on the strain energy stored due to torsion
21:18 - Explanation of the strain energy stored due to St. Venant torsion and warping torsion

Key Takeaways

- Torsional buckling involves deformation by twisting or a combination of twisting and bending.
- Thin-walled open sections are particularly susceptible to torsional buckling.
- Torsional flexural buckling occurs when the shear centre and centroid do not coincide in an axially loaded member.
- St. Venant torsion (uniform torsion) and non-uniform torsion are two types of torsional buckling.
- The strain energy stored when torsion is applied to a member can be calculated using specific mathematical expressions.