Combined Stresses: Torsion plus bending
Combined Stresses: Torsion plus bending
(OP)
AISC Steel Manual (ASD) 9th Edition Chapter H talks about checking combined stresses due to bi-axial bending and axial loads.
Given that a member is subject to bi-axial bending and torsion, and pure torsional stress is obtained, what should be the combined stress check equation?
What about bi-axial + axial + torsion?
I appreciate your input in advance.
Given that a member is subject to bi-axial bending and torsion, and pure torsional stress is obtained, what should be the combined stress check equation?
What about bi-axial + axial + torsion?
I appreciate your input in advance.






RE: Combined Stresses: Torsion plus bending
sigma-x (major axis bending stress)
sigma-y (minor axis bending stress)
tau (shearing stress, torsional and vertical shear)
sigma max, sigma min = (sigma-x +sigma-y/2) +/- ((sigma-x-sigma-y/2)^2 + (tau)^2)^0.5
I hope this helps
RE: Combined Stresses: Torsion plus bending
Should the term be [(sigma-x + sigma-y)/2]?
Assuming sigma, max and sigma,min gives the maximum and minimum actual combined stress, what allowable stress shall be used to compare this to?
Thanks for elaborating.
LRFD 3rd Edition talks of combined forces and torsion in Appendix H but no parallel info in the ASD...
RE: Combined Stresses: Torsion plus bending
http://www.efunda.com/formulae/solid_mechanics/mat_mechanics/mohr_circle.cfm
What shape are you checking?
RE: Combined Stresses: Torsion plus bending
Situation I have is a tube steel (HSS8x4x1/4) laid horizontally. Assume pinned ends.
Loading consists of gravity loads (self weight plus a black box attached near midspan) and lateral load of 4 kips at the black box. This lateral load is applied with eccentricity imposing torque in the member.
There is no axial tension or compression.
Thanks for the link. Nice refresher course in mechanics...
RE: Combined Stresses: Torsion plus bending
http://www.aisc.org/ContentManagement/ContentDisplay.cfm?ContentID=4203
See section 7.2
RE: Combined Stresses: Torsion plus bending
tg
RE: Combined Stresses: Torsion plus bending
RE: Combined Stresses: Torsion plus bending
You are correct. The term be [(sigma-x + sigma-y)/2]
Thanks for carefully reviewing the formaula.
Lutfi
RE: Combined Stresses: Torsion plus bending
Thanks y'all for your input.
Cheers