How do you include masonry partitions in beam design?
How do you include masonry partitions in beam design?
(OP)
i have searched for this issue in other threads but have not found a helpful answer, so here goes the question: what is the best way to address masonry partition walls in a building where the uniform loading can be as high as 60 psf for a bay? I see in IBC that minimum partition loads of 15 psf can be ignored with live loads of 80 psf, but I do not want to under design on the dead load side... right now I am using 80 psf DL (55 psf - floor system, 10 psf beams, 5 psf misc mech, and 10 psf partition/misc DL) and the prescribed LL of 80 to 150 psf. For beams with a wall along hte entire lenght, I am ok designing for the wall, but tyring to design each beam/girder for individual wall loads seems silly and excessive... need advice...






RE: How do you include masonry partitions in beam design?
The 15 psf value is pertaining mainly to wood walls. CMU weight, a dead load, I would always add extra regardless of the live load.
Mike McCann
MMC Engineering
RE: How do you include masonry partitions in beam design?
If you know the location of the blockwalls (i.e. starter bars will be provided when casting the slab) then calculate and include the weight of the cmu wall.
You will also need to look at the deflections that occur after the block partitions have been constructed (i.e. additional deflections due to creep and shrinkage).
I believe the methodology of designing for this in the US is to multiply your instantaneous deflection by 2 and this will be the additional deflection due to permanant loads (incremental deflection).
Keep your incremental deflections to span/500 and the total long-term deflections to span/250. Also, provide adequate control joints in the masonry mid-span where the beam curvatures are the greatest.
RE: How do you include masonry partitions in beam design?
RE: How do you include masonry partitions in beam design?
Unless my live load is very high I find that I need to account for the CMU walls. It can be a pain in the neck chasing them around and keeping up with the layout since the architects will place them willy nilly throughout the building.
RE: How do you include masonry partitions in beam design?
1. They get heavy pretty quickly (depends on height) and you'll find that you almost always have to provide a beam directly to support the wall line if you have steel floor framing (subject to L/600 criteria). On concrete floors, it may or may not be able to support the weight. Most of the time, you have to provide additional reinforcing as a minimum.
2. You're penalizing your floor system when other options are possible on the cheap. If the architect is after the look of the exposed cmu, you could easily get that with steel studs and masonry veneer. If it is the fire rating he is after, steel studs and gyp-board can give you at least 2 hour rating (or more with the masonry veneer). This assembly is way cheaper than CMU plus the associated cost of beefing up your floor framing.
3. The architect can easily rearrange the cmu locations and you'll be chasing the new locations, checking and reviewing the impact to your floor framing. That will not be the case for steel stud walls.
Mike is right. Also, try to calc out 2 or 3 locations and you'll find that you just can't make a blanket assumption that an increased design LL will take care of it. Increasing your design DL will take you back to my 2nd reason. You really need to look at each cmu location and review how it is affecting you floor framing. That's why I always go back to the architect first and "beg" to change the material by explaining the consequences.
http://www.dfoxonline.com
.....executing your vision.
RE: How do you include masonry partitions in beam design?
RE: How do you include masonry partitions in beam design?
Agreed that CMU partitions on elevated floor slabs are not desireable, but sometimes there is no choice if it's client-driven. I just had the same situation where the partitions were CMU for security purposes.
RE: How do you include masonry partitions in beam design?
RE: How do you include masonry partitions in beam design?
This won't work if you have a door opening in the span.
RE: How do you include masonry partitions in beam design?