Lateral Torsional Buckling
Lateral Torsional Buckling
(OP)
Will lateral torsional buckling ever control the stress in the tension flange of a singly symmetric member?
Lets say I have a wideflange with a channel on top. The top flange will only be in compression and the bottom flange will only be in tension. (uniform loading, single span.) I am checking the top "flange" stresses (beam flange+channel) independently of the bottom flange stresses.
Can the bottom flange be affected DIRECTLY from LTB? Obviously if it governs the top flange, that will be an indirect affect.I am under the impression that the bottom flange need only be checked for yielding .
Lets say I have a wideflange with a channel on top. The top flange will only be in compression and the bottom flange will only be in tension. (uniform loading, single span.) I am checking the top "flange" stresses (beam flange+channel) independently of the bottom flange stresses.
Can the bottom flange be affected DIRECTLY from LTB? Obviously if it governs the top flange, that will be an indirect affect.I am under the impression that the bottom flange need only be checked for yielding .






RE: Lateral Torsional Buckling
EIT
www.HowToEngineer.com
RE: Lateral Torsional Buckling
RE: Lateral Torsional Buckling
I was following the example in Design Guide 7, where he considering yielding as the only limit state for the tension flange, and the top flange is controlled by combined bending between LTB and minor axis bending (although, his channel has a cap). I had never thought of it in this way before, and wanted to get some other opinions. It seems as if it LTB controlled bending in the top flange, the same would be true for the bottom flange, but perhaps if the beam is only symmetrical about one axis, that is not the case?
RE: Lateral Torsional Buckling
RE: Lateral Torsional Buckling
LTB is not directly related to tension flange capacity. A beam that passes yielding checks but fails LTB checks, can have the top flange braced in a manner to resist the out of plane buckling forces.
RE: Lateral Torsional Buckling
RE: Lateral Torsional Buckling
While LTB controls the beam, the author does not consider the stresses from LTB when checking the bottom flange - the only stresses he considers here are from yielding.
RE: Lateral Torsional Buckling
I also assumed that this is a simply supported beam and not a continuous member. If it is continuous, then the bottom flange should be checked for LTB when in compression.
RE: Lateral Torsional Buckling