torsional rigidity constant (J) and the distance of max shear (CTOR)location

frontdotardUrban and Civil

Nov 15, 2013 (3 years and 6 months ago)


When beams experience a torque loading, the angle of twist (rotation) depends on 2 important factors called the
torsional rigidity constant (J)
and the distance of max shear (CTOR)


from the neutral axis.

In 2010, we now have the ability to
enter these values in the beam definition dialog box.

Depending upon the geometry and loading conditions,
a torque load can be induced in the beams which can significantly affect the results like
axial forces and bending moments

Two cases are prese
nted below.

Wide flange I Beam (W12x72) and Columns (W14x90):
Column bottoms are fixed and a load of 1000 lb/ft is applied on the wide flange beam.

Results: Case 1

There is no induced torque or torsion on the beams and the results of interest come out as expected on the horizontal beam.

Case 2: Because of the offset, the columns start to see a torque load. If the proper values for torsional con
stant and max shear location is not
entered on these column definitions, the results will be incorrect. Let’s take a look at the axial force and wide flange beam

bending moments

Results: Case 2 without proper values of J and CTOR

Results: Case 2 with proper values of J and CTOR

For W section I beams, you can get the value of torsional constant from the SolidWorks Structural Steel toolbox or use the at
tached excel
calculator that I created for this.

For the CTOR value, u
se the excel calculator.