Penndot Bar7 - Lateral Torsional Buckling
Penndot Bar7 - Lateral Torsional Buckling
(OP)
I am checking through a noncomposite steel beam analysis for a bridge beam (inventory/operating rating). It seems that the software output produced by the other engineer does not check lateral torsional buckling. I can't make sense of why the software is not checking it. The diaframs are spaced at about 15 feet which is beyond even lr for this beam. I would think for the compression flange to be considered braced, the friction between the deck and top flange alone would not suffice. That is the only rationale I can come up with behind why it is doing this. Has anyone else used this program?






RE: Penndot Bar7 - Lateral Torsional Buckling
BA
RE: Penndot Bar7 - Lateral Torsional Buckling
Is it simply supported?
All about Eurocodes:
http://www.DesignToEurocodes.com
RE: Penndot Bar7 - Lateral Torsional Buckling
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Qshake
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RE: Penndot Bar7 - Lateral Torsional Buckling
Regards,

Qshake
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RE: Penndot Bar7 - Lateral Torsional Buckling
2. Are you saying that the metal deck was not welded to the beam? ("the friction between the deck and top flange alone would not suffice").
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Penndot Bar7 - Lateral Torsional Buckling
It is also not uncommon to find non-composite construction depending on the span length or that the bridge is old enough no composite connection was used. In cases where no shear connectors are used and the concrete deck doesn't extend past the top of the top flange a reliable connection to provide lateral restraint can't be had.
Yes, the spacing of the 15' is between cross-frames or diaphragms (or both as used in bridge terminology.). Diaphragms generally refer to transverse members that use both shear and bending to resist forces between bridge girders and cross-frames describe transverse members that resist forces primarily in axial action, truss members.
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Qshake
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RE: Penndot Bar7 - Lateral Torsional Buckling
I assumed it was metal deck from the OP but that would have been puddle welded to the beam and would provide lateral restraint, even if not composite.
I have to admit though, I never ventured into the dark arts of bridge design, so I might well be missing something, especially nomenclature.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Penndot Bar7 - Lateral Torsional Buckling
All that said, the OP didn't elaborate on the deck construction nor the forming method so at this point it's all conjecture. Not even sure what era this bridge was constructed.
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Qshake
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RE: Penndot Bar7 - Lateral Torsional Buckling
Thanks again.
RE: Penndot Bar7 - Lateral Torsional Buckling
Regards,

Qshake
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