New CMU wall on existing 4" slab on grade
New CMU wall on existing 4" slab on grade
(OP)
I am a structural engineer on a project where we are putting 8" cmu walls (approximately 12' high) on top of an existing 4" slab. I'm not overly concerned with the bearing of the cmu on the slab (if the slab cracks it's acceptable), however even if i tie the wall at the roof, does anyone have any recommendations for the interface between the cmu and existing slab? Would you dowel into the existing 4" slab with 3" of embedment? I'm not sure exactly what this would achieve.
Suggestions anyone?
Suggestions anyone?





RE: New CMU wall on existing 4" slab on grade
How are you going to defend using a 4" thick "footing" for a load-bearing wall?
RE: New CMU wall on existing 4" slab on grade
RE: New CMU wall on existing 4" slab on grade
I am thinking about putting #4 dowels @ 48" and attach to the bottom of deck using some sort of a slip connection. Do you think getting 2-3" embed is going to add a lot of resistance to sliding?
RE: New CMU wall on existing 4" slab on grade
I agree that the effectiveness would be very minimal.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: New CMU wall on existing 4" slab on grade
Here is the
link...http://www.wbdg.org/ccb/DOD/UFC/ufc_3_320_06a.pdf
If you go to page 14 (section/page 3-4) you will notice they include a 4" slab as having bearing resistance.
Also, since these walls are rather spread out and in isolated conditions, the statement in the commentary for chapter 15 which says that it is 'generally applicable to ... mats supporting several columns or walls...' doesn't appear to apply. I wouldn't consider this a 'mat' as it is not required to spread out a concentrated load.
RE: New CMU wall on existing 4" slab on grade
This would give more lateral resistance than the dowels, but would be more costly labor-wise, obviously.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: New CMU wall on existing 4" slab on grade
If the area has any forklift traffic in it, I would consider the doweling; otherwise, no (unless seismic of course...but then small dowels are not going to do much for seismic resistance anyway).
RE: New CMU wall on existing 4" slab on grade
RE: New CMU wall on existing 4" slab on grade
Dik
RE: New CMU wall on existing 4" slab on grade
I know it's not load-bearing.
Also consider closer spaced control joints in the wall to account for possible differential settling along the wall length.
RE: New CMU wall on existing 4" slab on grade
RE: New CMU wall on existing 4" slab on grade
RE: New CMU wall on existing 4" slab on grade
RE: New CMU wall on existing 4" slab on grade
point being i've seen these short dowels put in all the time on slabs-on-grade and slabs-on-deck.