# Torsion

The twist or deformation of a body set up by a torque.

## Notation

The following notation is used throughout the torsion topic, unless noted otherwise:

• $B$ ... bimoment
• $I_{\omega}$ ... sectorial moment of inertia
• $\phi$ ... angle of rotation due to torsional moment
• $\phi'$ ... first derivative of $\phi$ with respect to the local X axis of the member
• $\phi''$ ... second derivative of $\phi$ with respect to the local X axis of the member
• $\phi'''$ ... third derivative of $\phi$ with respect to the local X axis of the member

## References

• AISC Design Guide 9: Torsional Analysis of Structural Steel Members (1996)
• Michael R. Lindeburg: Civil Engineering Reference Manual for the PE Exam, 9th Edition, 2003, p. 45-14 (eq. 45.54)

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