Do I need a separate footing if a post is added on slab on grade 2

[dcceecy]

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.

 

[PMR06]

The 4 bolt rule does not explicitly require the 4 bolts be non-collinear...

 

[steellion]

I wouldn't want to be the theorhetical 300 lb construction worker swinging from the top of a column with 4 anchor bolts in one line.

 

[Ltwine]

Yep, the last time someone stacked 4 bolts.

 

[ToadJones]

I thought the 4-bolt requirement was for erecting columns that would be free-standing for some time during erection...like a flag pole.
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.

 

[msquared48]

"4 anchor bolts for a tiny post. Engineers need to use logic, not just books."


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

 

[Lion06]

I agree that engineers need to use logic and not just books. That being said, when there is a legal requirement (whether you believe it to be valide of not) that you choose not to follow, and something bad happens...... you can rest assured that someone will be held to account.

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?).

 

[steellion]

I couldn't find the column/post distinction on the OSHA site. But a quick internet search produced this result. I can't validate it, but it seems official:

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.

 

[beton1]

Was there not a thread a few months ago regarding the 4 and 2 bolt situation?

 

[hokie66]

I doubt there is a subject which has not already been covered on this site before. Doesn't stop us from going over them again.

 

[msquared48]

The pipe column the OP mentioned is only 100 to 150#, so, based on the definition above, 2 bolts would be OK.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ltwine]

For OSHA inspectors concern, anybody get injured/killed, a citation will be issued (for vertical permanent member with fewer than 4 bolts) with emphasis on fastening not meeting OSHA recommendation. Consequence? You may prevail through appeal, but first to check with your lawyer & insurance company. Again, it is a practical/practice issue, not strength, and is meant to be fool proof.

 

[BAretired]

The 300# weight limit seems to make sense. Spandrel columns in single story buildings are usually less than 300#, so the practice in Canada seems to be consistent with the OSHA standard even if it does not have to be.

BA

 

[Ltwine]

Please read steellion's post again. I don't think OSHA suggests 300# is the cut for fastening concerns. Formal explanation from OSHA is required. Maybe there is already one, but burried in somewhere.

 

[BAretired]

Ltwine,
Yup, I think you're right.

BA

 

[Ltwine]

Just hope no one get misled before OSHA clears its stance on this.

 

[paddingtongreen]

Perhaps, a check with OSHA to see if there is a code case?

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.