Lateral Support for Steel Beam

[VictorAK]

Hello,
If a wood member is bolted to the web of a steel beam, and wood joists are fastened to the wood member with hangers on only one side of the beam, what does this do to the moment resistance of the beam? Is the beam considered laterally suppported?

 

[apsix]

If the member is bolted at the top of the web (just under the top flange) and the floor forms a reasonable diaphragm, yes, I would consider it to be laterally restrained.

 

[mmillerpe]

If the floor diaphragm runs over the top of the beam and is fastened to the steel directly, or fastened to a nailer attached to the top of the beam, then I would consider the beam braced.

If the floor diaphragm stops short of the beam, then you would have to look at the pull out capacity of the joist hanger to see if it can provide the required bracing load.

 

[JoshPlumSE]

To be consided a point of support for a beam, AISC (in appendix 6.3 of the 2005 spec) says that the bracing needs to restrain against twist (i.e. rotation) of the section.

I'm not convinced that something bolted into the web would qualify. If the wide flange beam twists, then the hangers will do almost nothing to provide restraint against this twist. Right?

Now, if you also have a diaphragm restraining the lateral translation of the top flange, then I would consider it to be braced. But, without that extra support from the diaphragm, I would not feel comfortable with assuming those beams as brace points. At least not after reading that section of the AISC appendix.

 

[apsix]

I'll reconsider my position (thanks nmillerpe, Joshplum).

If the hanger supports the joist at the bottom only, as is likely, the beam's top flange wouldn't be restrained.

 

[Bobber1]

If your hangers rely on nails in withdrawal to provide rotational or lateral restraint, that's not good.