Do I need a separate footing if a post is added on slab on grade
Do I need a separate footing if a post is added on slab on grade
(OP)
The existing basement has 5" slab on grade reinforced with WWF.
Now I have a new post with a load of 5.72 kips.
If I assume the soil capacity is 2000 psf, it seems I need a 3 ft^2 of footing.
I am going to use 3 1/2" standard pipe.
if I can hide this post in a parition wall and put a steel plate below the pipe, and anchor the plate into slab on grade.
Do I need the separate footing? because if I need one, I have to cut the existing slab.
if I do not put separate footing, is that load going to make the slab on grade around the post crack?
any suggestions? Thank.
Now I have a new post with a load of 5.72 kips.
If I assume the soil capacity is 2000 psf, it seems I need a 3 ft^2 of footing.
I am going to use 3 1/2" standard pipe.
if I can hide this post in a parition wall and put a steel plate below the pipe, and anchor the plate into slab on grade.
Do I need the separate footing? because if I need one, I have to cut the existing slab.
if I do not put separate footing, is that load going to make the slab on grade around the post crack?
any suggestions? Thank.






RE: Do I need a separate footing if a post is added on slab on grade
Never, but never question engineer's judgment
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
I would saw the slab to remove it and create a separate footing of proper dimensions and thickness. Then you know what have and are responsible for.
A concentrated load on an unknown slab is not reliable especially if there are any early signs of cracking.
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Do I need a separate footing if a post is added on slab on grade
You are correct that the slab may crack if it is only bearing on the slab with no existing or new footing.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Do I need a separate footing if a post is added on slab on grade
Actually the client is remodeling an office building.
I was trying to save cost. if i do not put a footing and cracks show up, it'll cause trouble for us.
I think I am going to cut the existing slab and put a 2'x2'x12" deep footing for the post.
Thanks.
RE: Do I need a separate footing if a post is added on slab on grade
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Do I need a separate footing if a post is added on slab on grade
BA
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
http:/
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Do I need a separate footing if a post is added on slab on grade
Aren't you glad we don't have to put up with that nonsense?
RE: Do I need a separate footing if a post is added on slab on grade
Why would it cause trouble for you? When the square cut is made in the slab for the footing, the slab will eventually crack anyway due to the re-entrant corners resulting from the cuts.
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
DaveAtkins
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
Jr, you can't just ignore codes that you don't like.
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
Hir wrong button, sorry.
RE: Do I need a separate footing if a post is added on slab on grade
BA
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
We use to bolts in crane shafts that are tied to bulding shafts becasue there is never a time when just the baseplate is holding the column.
I agree...use some logic here. Cookbooks are for chefs.
RE: Do I need a separate footing if a post is added on slab on grade
I would find it hard to believe that this rule was made by an OSHA "Engineer", as I did not know they had any on staff.
There have been failures during erection of columns with only two bolts that involved injury or loss of life. Hence the regulation - to protect us from ourselves.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Do I need a separate footing if a post is added on slab on grade
We as engineers design to the final, constructed state. Means and Methods are in the Contractor's realm, and since we have no control over how the column is erected, and when/how it is stabilized during erection, it seems prudent (in my opinion) to provde 4 anchor bolts as required by OSHA.
As noted above, it is based on self-weight (not the load it's carrying), but I believe there is another criteria in there as well (maybe member length?).
RE: Do I need a separate footing if a post is added on slab on grade
A "column" per OSHA is defined as a vertical member that is greater than 300
pounds in weight and/or part of the "primary skeletal framing system".
Anything supporting the main floors, roof and walls of the building and/or
part of the lateral load system is a "column" by OSHA.
A "post" per OSHA is defined as a vertical member that is less than 300 lbs
in weight, axially loaded only, and not part of the primary skeletal framing
system. Tubular members supporting stairs and mezzanines would be most
likely to qualify as "posts" by OSHA.
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
BA
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
Yup, I think you're right.
BA
RE: Do I need a separate footing if a post is added on slab on grade
RE: Do I need a separate footing if a post is added on slab on grade
To minimize cracking at re-entrant corners, I had them core bore the corners and then saw cut from tangent point to tangent point. It was pretty successful.
Michael.
Timing has a lot to do with the outcome of a rain dance.