Beam Question

**Bill Wieczorek** · 10-04-2007, 03:01 PM

Is it required that steel beams be cemented in the beam pocket or can they be set without concrete.

Similar Threads:

Chad Fabry · 10-04-2007, 03:28 PM

I'll guess at it in a round about way.

If the beam was supported by an engaged column instead of in a pocket, you wouldn't glance at it twice.

If it were wood it would be prohibited.

**Billy Stephens** · 10-04-2007, 03:31 PM

Originally Posted by Bill Wieczorek

Is it required that steel beams be cemented in the beam pocket or can they be set without concrete.

Bill,
Can you give us a little more information? Residential?Commercial? Pictures? Size?
Where they fastened by some means?
IRC 2003 only goes to 60x36 in secR505.

**Bill Wieczorek** · 10-04-2007, 03:50 PM

A fellow inspector called me to ask so I don't have pictures. The beam 40 feet is resting in beam pockets in a residence. Its seated into the pocket by 4 inches on each endand there are 3 supporting posts. I didn't think cementing in the ends was required but I'm drawing a blank so I thought I'd ask. Oddly I looked at mine and they are cemented in, hence the question. Its heck to get old and not remember little things.

**Billy Stephens** · 10-04-2007, 03:54 PM

Bill,
I didn't see anything in IRC 2003 that requires cemented into the pocket.

Any other takers?

**Jerry Peck** · 10-04-2007, 06:59 PM

I would think that cementing them into the pocket would be more for fire protection than anything else. It certainly will not hold that beam in place should it decide it needs to move.

That would require either bolting to poured concrete or welding to an embedded plate.

If that is supporting a load above, what is holding it down (from uplift)?

**Eric Barker** · 10-04-2007, 07:00 PM

Not worth pointing out. What's concrete fill going to do? The beam is not going anywhere (if it does there's much bigger concerns at issue). Not much different than loose bolts and and nuts at the beam/column connections - a none-issue with me. I've seen a lot of things in a basement/crawl that have moved over time but never, ever a beam that was properly supported. There's just too much weight on it for it to shift.

**Bruce Breedlove** · 10-04-2007, 09:31 PM

One purpose of grouting (I prefer that term to "cementing") the beam end in a beam pocket is to resist rotational movement. Rotation is more of a concern when the beam is tall and narrow and less of a concern when the beam is the same width as the height.

If the beam is tall and narrow AND is very long AND does not have lateral support along its length it is more likely to rotate. Having rotational restraint(s) at the end(s) of the beam would be important in that situation. Properly placed grout will restrain the ends of the beam from rotation as the rotating beam will be placing the grout into compression against the sides of the pocket and grout, like concrete, is very good in compression (but not tension).

I don't think the fire protection provided by grouting the beam in the beam pocket makes any difference whatsoever. Assuming a simple beam (no rigid end connections), the stresses at the ends of the beam are very small compared to at mid span. If there is a fire hot enough to cause the steel beam to lose strength it will fail at mid span long before it fails at the end supports.

**Jerry Peck** · 10-05-2007, 05:02 AM

Originally Posted by Bruce Breedlove

I don't think the fire protection provided by grouting the beam in the beam pocket makes any difference whatsoever. Assuming a simple beam (no rigid end connections), the stresses at the ends of the beam are very small compared to at mid span. If there is a fire hot enough to cause the steel beam to lose strength it will fail at mid span long before it fails at the end supports.

I'm thinking more along the lines of fireblocking. Fill the beam pocket with grout and you've fireblocked that open area up into the wall (at least as I am envisioning the way it would be configured).

As far as rotation goes, I am envisioning a standard flange ("I") or wide flange ("H" on its side) beam which is not that tall, the ones I've seen did not have a large height/width aspect ratio, thus rotation would not be an issue.

Without a photo, who knows.

**Eric Barker** · 10-05-2007, 05:56 AM

Bruce,

You're referring to a wood beam (obviously). I don't like the idea of wood encased on concrete - too much moisture retention and possibility of decay.

As for cementing terminology. Cement is the mix to make concrete. Though I doubt that few would not understand cementing the pocket.

**Bruce Breedlove** · 10-05-2007, 09:45 AM

Eric,

No, I'm talking about a steel beam. I agree, grouting a wood beam is not recommended.

Not all steel beams are compact. As I said earlier, a beam that has a height much greater than its width is subject to rotation. Like Jerry , most steel beams I see do not have a high height/width ratio but on occassion I do see them. Wood beams by their nature do have a high height/width ratio.

The attached image shows how rotation occurs in a steel beam.

**Bill Wieczorek** · 10-05-2007, 02:35 PM

What would make a beam twist as shown, maybe a fire perhaps.

**Eric Barker** · 10-05-2007, 03:06 PM

Bruce,

Interesting. Can't remember seeing a high profile beam in residential construction. In such a case the filling of the pocket makes sense.

**Bruce Breedlove** · 10-05-2007, 03:40 PM

Originally Posted by Bill Wieczorek

What would make a beam twist as shown, maybe a fire perhaps.

Asymmetrical loading. Have you ever seen a beam where the support post was off center? That's how it starts. As the beam rotates a little the loads become more and more asymmetrical causing the beam to rotate a bit more causing the loads . . . The higher the height/width ratio the more a problem with those off center loads.

Does it ever happen? You bet it does. It is more common on tall, skinny beams.

I did the repair on a double wood lam beam that had rotated so much the bottom of the beam had moved almost 6". That beam was very deep (vertically) - maybe 14" - and was very narrow - two 2 1/2" or 3" widths - so the height/width ratio was high. There were one wall framed into the beam near the far end but there were no lateral braces along the rest of its length and the near end of the beam was free to rotate in the beam pocket.

This tall, skinny beam was balancing on a few teleposts. Try balancing a credit card on edge on the end of a pencil between your hands and squeeze. That should give you an idea of how precarious this arrangement was.

Everything is fine if the beam is perfectly aligned with the post but, as we know, this does not always happen.

**Jerry Peck** · 10-05-2007, 07:47 PM

Another thing which will cause that rotation is overspanning a beam.

When the beam starts to deflect, it also starts to rotate, the more it deflects, the more it rotates. The more it rotates, the weaker it becomes, the more it deflects.

Self-fulfilling failure, it just becomes a matter of time.

I've also seen some, but as Bruce said, only on high height/width ratio beams. I guess that also could be because smaller beams are loaded less than tall beams, thus the loading on an overspanned beam would have less of that effect.