need help on footing sizes for a 50 x 100 steel building 1

[acorvettekid]

in the foundation phase of a new 50 x 100 steel building. Didn't realize the footings plan didn't come with the building. I don't want to go overboard with concrete but also don't want trouble in the future. Any help would be appreciated. The building is a clear span, 4 bay on 25' spacing with 3 sets of main beams. I'm in eastern NC so frost heave is not an issue. I'm planning 24" deep x 36" x 36" for the main column footers with a perimeter footing of 18" x 18" maybe slightly wider on the end walls. My question is... is this enough ?? My understand is wind uplift is the main priority with having enough concrete. We are in a hurricane area. I've seen one other post on here and they were saying 4 ft x 4 ft x 4 ft footers for the main columns.... this seems like overkill to me. Thanks in advance !

 

[par060]

You need an engineer to design the foundations. Guessing isn't an option.

 

[JedClampett]

Listen to par060, there's more to a Metal Building Foundation than you think. There's lateral loadings, uplift, besides all the normal downward cases.
And when you squint and look a the fine print, it turns out that the PEMB's supplier's anchorage is just a suggestion, so you're responsible for that, too.
Hire a structural engineer. Look at it this way, you got a cheap building, pay a little for an engineer.

 

[fattdad]

pre-engineered metal buildings never come with foundation plans. So, you need an engineer to design your foundations. That design must consider the soil characteristics and the imparted loads. You are likely correct, the greatest load is likely the uplift load from wind. There will also be a horizontal component that has to be resolved. How will you handle that? Via passive resistance on the buried footing? Via the horizontal support of the concrete slab? I certainly don't know. . .

Hire a structural engineer to work up your foundaiton plan. Fair warning though, the structural engineer will want a geotechnical study.

f-d

¡papá gordo ain’t no madre flaca!

 

[acorvettekid]

the company I purchased the building from can supply the foundation plans for a fee. They did not mention anything about geotechnical studies or anything else. My thoughts by posting here was hopefully someone else had erected the same size building and would post some dimensions that were used on their building. The 4x4x4 sizes above came from this site, but I think he went way overboard... 279 yards of concrete is crazy. I want the building to stay in place, but don't want to break the bank doing it.

 

[JAE]

So you would depend on someone with a similar building somewhere to size your footings for such a building? Stupid.

Hire a structural engineer, licensed in NC, to design the footings for you. These would depend upon your local soils conditions and loading.

You can't use someone else's building to design your footings as things could be different at your site such as:

1. Wind loads can vary with location and site contours
2. Seismic loads can vary
3. Column reactions thus will be different.
4. Snow loads can be different
5. Soil load bearing capacity can be different.

When I say "different" above I mean anywhere from slightly to vastly different.

Also - depending on where you are building this you may or may not legally be required to use a licensed engineer.
Even if you are not technically and legally required to use an engineer you would be foolish to not do so.

 

[acorvettekid]

Thank you.

 

[ukengineer58]

Is this guy serious?

 

[ukengineer58]

What I meant by that was you give no indication that you have any idea if '279 yards of concrete ' is a lot, right on the limit or even a mistake and not enough. You may even find that your companies non understanding and what's seems like unwillingness to spend money on experts means you ended up with a grossly over designed foundation. I.e. if you have little soils info an engineer may simply make sure there's enough on a conservative basis. I.e. you think your saving money and your not.

 

[msquared48]

Been designing foundations for these things for 35 years now, and they are all different. I agree totally with asll the comments above.

Oh, and make sure whomever you use knows what a "hairpin" is and what it's function is. If he doesn't, don't use him (or her)...

Mike McCann
MMC Engineering

 

[dik]

IF the PEMB supplier can provide sealed drawings for this building and this site for a fee, this is likely the most cost effective approach. Give them a call.

Dik

 

[RareBugTX]

Even if the PEMB manufacturer can provide sealed drawings for the building's foundation it does not necessarily imply that the building would meet the lateral loading resistance not the mention all the other factors mentioned above. Now, what about soil report, are they providing it too, where's the PEMB main office and where is the building going to be erected.Now, speaking of lateral loading I have seen stamped plans that do not meet the most basic c&c detailing.

 

[cvg]

so we are back to square 1. Owner needs to hire a geotech and a structural engineer to finish the design and hurry because the steel is apparently being designed as we speak

 

[dicksewerrat]

cvg, my guess would be tht the steel was designed 15 years ago and they just tell the plant to stamp out NO. 13456-50100.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[shobroco]

And a further comment on JAE's "different": within 25 km of where I'm sitting right now I have snow loads varying from 2.5 kPa (>50psf) to 1 kPa (20psf) so what do they vary across the country (rhetorical question for the corvette kid).