Stability bracing for beams
Stability bracing for beams
(OP)
Hello All,
I'm wondering if the beam bracing requirements of App. 6.3.1 of AISC, 14th ed, for nodal bracing can be divided (equally or partially) among the total number of braces provided along the span. It seems like the braces would all help resist the beam as it started to laterally buckle, but the code doesn't address it in the required strength equation A-6-7.
Thanks!
I'm wondering if the beam bracing requirements of App. 6.3.1 of AISC, 14th ed, for nodal bracing can be divided (equally or partially) among the total number of braces provided along the span. It seems like the braces would all help resist the beam as it started to laterally buckle, but the code doesn't address it in the required strength equation A-6-7.
Thanks!






RE: Stability bracing for beams
However, the way to understand this is to see it as a brace force and stiffness required based on a set Lb with a beam size consistent with that Lb.
So if you have a 30 ft. beam with a certain vertical load, and you "try" Lb = 10 ft. you'd have two brace points.
The beam size that RESULTS FROM THAT Lb will require a resulting brace strength and stiffness at those points.
Now if you add braces at 5 ft. on center, that doesn't mean you now have higher brace forces.
The brace force and stiffness should always be consistent with the maximum Lb that the beam can tolerate.
Hope this is clear.
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RE: Stability bracing for beams
RE: Stability bracing for beams
Take it to a ridiculous extreme.... Add a brace every foot. It makes no sense that the stiffness required of every brace at every foot would be sky-high from the formula.
I think the assumption embedded in this stability system is that the designer will use the least-weight beam that works based on the chosen Lb distance.
Then, with that Lb, you have a set brace force and stiffness.
So for brace strength - which doesn't include Lb in the formula, the required strength is based on a set applied moment Mr. Again, I think the assumption here is that you have a decided-upon Lb value, a resultant beam size, and then at every brace point (per the Lb chosen) you have a brace force required.
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RE: Stability bracing for beams
Attached is a paper that may give a little more insight into beam bracing.
RE: Stability bracing for beams
RE: Stability bracing for beams
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