LATERAL BRACING
LATERAL BRACING
(OP)
IS A STEEL BEAM CONSIDERED LATERAL BRACED IF JOISTS ARE PERPENDICULAR TO THE STEEL BEAM(FLUSH FRAME) AND ATTACHED TO CONTINOUS WOOD BLOCKING WHICH IS SECURE TO THE WEBB? OR MUST THE STEEL BEAM BE BRACED AT THE TOP FLANGE BY SECURING WOOD NAILER TO FLANGE AND PLYWOOD SUBFLOOR ATTACHED?






RE: LATERAL BRACING
The compressibility of wood, coupled with the inability to affect a proper tensile connection (from the opposite side) limits its effectiveness in preventing flange buckling.
RE: LATERAL BRACING
I see the point about the condition where joists are only coming in from one side. Unless there is a positive connection between the joists and steel beam, the beam could conceivably buckle away from the joists.
But if the joists are on both sides, each providing a positive compressive restraint against sidesway translation, I would think you could consider the beam braced. The small amount of compressibility wouldn't seem to adversely affect the bracing.
If the beam was not heavily loaded, the lateral force, and stiffness required for lateral stability wouldn't be that significant.
What do you think?
We have typically used wood joists as bracing, but admittedly, we usually have the wood on top of the beam.
RE: LATERAL BRACING
I agree with you, just that conditions have to be right for wood to be effective bracing. In most cases it works fine, since as you say, the lateral load to prevent buckling is usually small (less than 500 lbf).
You mentioned the key to getting it to work correctly...make sure both sides in compression at start. Often, this is not done and the result is too much movement capability on one side of the beam.
Ron
RE: LATERAL BRACING
I would want to check the joists and joist-steel beam connection details for adequate stiffness, e.g, "Bracing for Stability", Yura & Helweg.
RE: LATERAL BRACING