A bar of uniform section fixed at one end and subject to a torque at the extreme end which is applied normal to its axis will twist to some angle which is proportional to the applied torque. This assumes that the bar is not stressed to a level greater than its elastic limit. This page includes various formulas which allow calculation of the angles of twist and the resulting maximums stresses. The equations are based on the following assumptions
1) The bar is straight and of uniform section
T = torque (Nm)
Formulas for bars of circular section
Formulas for bars of non - circular section.
Testing the values of J' obtained using the above equations (with η = 1) with the values obtained from the table below the following values result.
1)Channel section 430x100x64 calculated J' = 63,118 cm4. Table value 63 η = 1
Torsion in Sections. Structrual design
Important Note : In the notes and tables below J is used throughout for the
torsion constant for circular and non circular sections. .
In structural design the use of sections i.e I sections, channel section, angle sections etc. should be avoided for applications designed to withstand torsional loading. Hollow rectangular sections are best suited for these applications. Note: Values for J and C for square and hollow rectangular sections are provided on webpages as indexed on webpage Sections Index
Torsional /Buckling Properties for Hot rolled Sections
A few tables providing Torsional /Buckling properties for some steel sections are indexed below.
Pages in this section
- Channels..BS 4:Part 1 2005 Torsion/ Buckling Parameters
- Parallel Flanged Channels..BS 4:Part 1 2005 Torsion/ Buckling Parameters
- Rolled Steel Joists..BS 4:Part 1 2005 Torsion/ Buckling Parameters
- Tee Cut From Universal Column..BS 4:Part 1 2005 Torsion/ Buckling Parameters
- Tee Cut From Universal Column..BS 4:Part 1 2005 Torsion/ Buckling Parameters5
- Universal Beam Tee Torsion /Warping factors
- Universal beam Torsion Warping Factors
- Universal Column..BS 4:Part1 2005 Torsion/ Buckling Parameters