Gas station Canopy Footing 2

[knadia]

Hi,
The gas station canopy is 102'x30' and supported by 4 HSS columns. I am designing only the footing and making sure it is sized for a moment as well as axial load provided by canopy manufacturer. Below the canopy is a slab on grade. The bottom of each of the four footings will be 4'-0" below the finished grade. There is also a slab on grade for cars and trucks to drive up to fill up. Do I need to take into consideration any impact for loads from these vehicles onto my column footings?

 

[frv]

Yes.

 

[hokie66]

No.

 

[msquared48]

Definitely no.

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

 

[msquared48]

If the bottom of the footing was only at 2 feet down, I would say yes, but not at 4 feet. Any impact force will be too dissipated at that depth to worry about.

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

 

[knadia]

frv - Can you please elaborate?

 

[cvg]

question is a little unclear - do you really mean "impact loads" as in dynamic loading, or do you mean "impact from" static or slow moving vehicle live loads?

 

[msquared48]

The latter cvg. Moving vehicle impact loading - at 10 mph or less.

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

 

[knadia]

The latter is the correct answer. When cars/trucks pull up to fill up its usually slow speed. Or worst case when the oil tanker drives by to fill up the underground tank. Do I need to include the load of these vehicle on the footings for these columns that support the canopy?

 

[msquared48]

I would use a vehicle surcharge of 50 psf for passenger cars and trucks.

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

 

[ToadJones]

For vertical loading on the column footing, you should consider a surcharge load.
Any impact load from a vehicle actually running into the column is usually not a problem as curved bollards are usually installed around the gas pumps and columns.

 

[ToadJones]

Also, be careful to include the surcharge in proper combinations as it can both help/hurt your overturning calc's.
Sorry if I am stating the obvious.

 

[MHconc123]

Not sure if it would be relevant in this case but if you were to check the foundations presumably with the slab cast around them you may be able to distribute any lateral load over several foundations.

 

[DaveAtkins]

ToadJones is correct about curved bollards protecting gas pumps. I know--my 18 year old daughter drove her older sister's car into one a few weeks ago.

I have spent the last couple of weekends doing auto body repair work

DaveAtkins

 

[ToadJones]

Dave-
Better than hitting the gas pump!!!

 

[structuresguy]

I would say yes, and use the 50 psf uniform live load surcharge.

Oh, and Dave, I think I found a picture of your daughter's run-in with the pumps.

 

[DaveAtkins]

Funny picture!

Not funny for the owner of the SUV, of course.

DaveAtkins

 

[Ron]

No. Provide separate bollards for pump/column protection.

 

[frv]

Why wouldn't you design it for the impact of a vehicle?

It really isn't that stringent. I don't have the IBC in front of me, but it's something like 2 or 3 kips at 2'-3' above finished grade.

This loading is intended to account for a vehicle accidentally backing into it. And this is certainly a possibility.

Now, if you have the bollards as others have suggested, then you wouldn't need to design for the impact, as the bollards would absorb this.

 

[ToadJones]

I think the issue is being confused here....I do believe the OP was worried about surcharge on the footing, NOT inmpact on the column. This might be semantics.