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Deflection limit for steel beams supporting masonry partitions

Deflection limit for steel beams supporting masonry partitions

Deflection limit for steel beams supporting masonry partitions

(OP)

It has been suggested that steel beams of floors supporting masonry partitions be designed for a service load vertical deflection limit of span divided by 500 or 600 or perhaps even more stringent, to minimize the possibility of the partition cracking due to beam deflection. This would be under specified live load plus load applied after the partition is built, as well as the self weight of the partition.

Where is that limit given? Is it in the National Building Code of Canada or its User's Guide, or CSA S16.1? I can't find it, but I don't have the latest versions here at home. Or if not there, then where? Perhaps in NRC notes or an American publication?

RE: Deflection limit for steel beams supporting masonry partitions

See commentary D of the structural commentaries in the NBCC. Table D-1 note 2. vertical deflection of masonry wall supports must be less than l/480 or 20mm.

RE: Deflection limit for steel beams supporting masonry partitions

Across your southern boarder, it's l/600 or .3"

RE: Deflection limit for steel beams supporting masonry partitions

(OP)
Thanks jayrod.
To hawkaz - can you tell me which American Standard gives the L/600 or 0.3" (8± mm)?
Thanks.

RE: Deflection limit for steel beams supporting masonry partitions

(OP)
If Hokie66 is on here, can you tell me what the Australian Standard says in this regard?

RE: Deflection limit for steel beams supporting masonry partitions

AS1170.0 Table C1 - mid span deflections for floors supporting masonry walls is limited to L/500. Mid span deflection for underpinning beams supporting existing masonry walls is limited to L/750.

RE: Deflection limit for steel beams supporting masonry partitions

(OP)
Thanks nineninenine. Much appreciated.

RE: Deflection limit for steel beams supporting masonry partitions

This is from the Australian code AS4100

RE: Deflection limit for steel beams supporting masonry partitions

(OP)

Thank you Retrograde. A good Table to have. Does the Australian Code or Commentary explain or give examples of what they mean by "where provision is made to minimize the effects of movement"? It seems rather vague. Would a deflection space between the top of the wall and the underside of the floor structure above be considered as provision to minimize the effect of movement? Would provision of horizontal joint reinforcement be so considered? Or do they mean the provision of vertical control joints in the masonry?

Also, is the self weight of the wall to be included in the calculation? It would seem from the wording "after the addition of the partition" that the self weight of the would not be included, but I think self weight generally would be included...this wording is, in my opinion, a problem with Canadian and American Codes/Standards as well(although I have not looked at all of them).

RE: Deflection limit for steel beams supporting masonry partitions

I was looking at ACI 530-05, section 1.10.1.
I pulled up ACI 530-11, it is now section 1.13.1.4.1, but I don't see the .3" limitation anymore (l/600 still applies)

RE: Deflection limit for steel beams supporting masonry partitions

(OP)
Thanks Hawkaz. Does it say whether the weight of the wall is to be included in the deflection calculation?

RE: Deflection limit for steel beams supporting masonry partitions

It doesn't specifically mention this, but with the wall weight being DL, I have always included it.

RE: Deflection limit for steel beams supporting masonry partitions

(OP)

ok, thanks very much hawkaz.

RE: Deflection limit for steel beams supporting masonry partitions

Quote (ajk1)

Does it say whether the weight of the wall is to be included in the deflection calculation?

I've always included it in new builds. However, in an unshored application where a non-bearing wall above will be constructed quickly in one go, I think that you could make an argument for excluding the weight of the block. I think that you're only really interested in curvature that develops after the mortar sets.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Deflection limit for steel beams supporting masonry partitions

I have always used l/600 minimum, and sometimes l/1000 depending on the situation.

Mike McCann, PE, SE (WA)


RE: Deflection limit for steel beams supporting masonry partitions

Ajk1:
Whatever the final stl. beam deflection, you might consider making the bottom couple courses of the conc. blk. wall a horiz. reinforced masonry beam. Make the bot. course out a bond beam blk. with some rebar. Fill the next course of regular blk. with grout also, and put some joint reinforcing in several of the lower joints. This will help the whole wall act as a deep beam, and do some of its own spanning was the stl. bm. starts to deflect. It will also inhibit any cracking from the bottom of the blk. wall due to the stl. bm. deflection. It will relieve the blk. wall loading on the center portion of the stl. bm., as the stl. bm. starts to deflect.

RE: Deflection limit for steel beams supporting masonry partitions

(OP)

ok.

And thanks dhengr for the good idea. Much appreciated.

RE: Deflection limit for steel beams supporting masonry partitions

Quote (ajk1)

Thank you Retrograde. A good Table to have. Does the Australian Code or Commentary explain or give examples of what they mean by "where provision is made to minimize the effects of movement"? It seems rather vague. Would a deflection space between the top of the wall and the underside of the floor structure above be considered as provision to minimize the effect of movement? Would provision of horizontal joint reinforcement be so considered? Or do they mean the provision of vertical control joints in the masonry?

Also, is the self weight of the wall to be included in the calculation? It would seem from the wording "after the addition of the partition" that the self weight of the would not be included, but I think self weight generally would be included...this wording is, in my opinion, a problem with Canadian and American Codes/Standards as well(although I have not looked at all of them).

The Code does not elaborate but generally I would consider both provision of horizontal joint reinforcement and the provision of vertical control joints are acceptable.

Normally I would include the weight of the partition in the calculation.

RE: Deflection limit for steel beams supporting masonry partitions

(OP)
Thanks very much Retrograde for your wise counsel and help. It is very useful and much appreciated.

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