Pad foundation sizing

nstocks · 4 May 2010

Hello,

I've been searching the internet and several books on basic sizing of pad foundations. I want to know the overall depth, width and length of the pad and also how far apart they are to be placed.

The building is a Cinema ( not actually going to be built ), so I am using steel frame construction. The span of the largest wall is 70 metres and the structure is a long span... 2 floors with 2 cinema rooms on the first floor.

I realise this is a broad question but without the time or requirements of the structural load, I just need a basic guidance.

Any help is appreciated ( arrogance or rudeness is not, as per my first post on this forum ! )

Thank You

2929twin · 4 May 2010

nstocks. Sorry I think this question is too complex for anyone to commit a guess at. If the project is to go forward you will have to give it over to an archi./structural eng. who with all the details can calculate, not guess the answers

nstocks · 4 May 2010

It's just for a Uni project... I need to show the foundations in a simple eleation... I'm just not sure how far apart the pads are suppose to be

Also, if anyone has a good quality detail section of a pad foundation and steel fame, that would be very helpful

Thank You

jeds · 4 May 2010

The size of the pad is determined by load and carrying capacity of the soil. Basically, if the load was 150kN and the capacity of the soil 150kN/m² then the pad would need a bearing area of 1m². It's not exactly that simple because there are safety factors to take into consideration, but that's the principle.

nstocks · 4 May 2010

That what I though would be implied... Well the deadline is Thursday so I think that I will just show the details of such construction... If my tutor asks for the foundations in the section then I will explain how much time it will take to work out the correct details...

Thank You

noseall · 4 May 2010

Are pad found's the same as a raft?

nstocks · 4 May 2010

No, A pad is an isolated block of concrete basically. A raft normally spans across the whole span of the building, which is suitable for lighter loads

( someone might want to verify ! )

Shytalkz · 4 May 2010

noseall said:
Are pad found's the same as a raft?

Have you forgotten all that I taught you, Nose?!

noseall · 4 May 2010

Shytalkz said:
noseall said:

Are pad found's the same as a raft?

Click to expand...

Have you forgotten all that I taught you, Nose?!

Come clean Shy, where 'ave ya been?

Her Majesties pleasure?

freddiemercurystwin · 4 May 2010

or Fat Camp?

Deluks · 4 May 2010

Ferkarama! Fiver says he's been lurkin' all this time!

Static · 5 May 2010

nstocks said:
The building is a Cinema ( not actually going to be built ), so I am using steel frame construction. The span of the largest wall is 70 metres and the structure is a long span... 2 floors with 2 cinema rooms on the first floor.

Not only a broad question but a question lacking alot of details..
Like someone said pads are based on soil allowable bearing pressure.. and load from columns..
But that said Uni questions are rarely complete as far as info goes..

Firstly are you doing a Stuctural or Architectural course?

6m centres for column grids.. both dirs as first floor will internal columns..

theoldun · 5 May 2010

nstocks. Quick story. 1957. Just finished national service. Work very tight. Only job I could get digging pads. Old money 8ft square 6ft deep. Two stage throw, then throw in lorry. Just finished first one. Old boy about 70 came round to inspect. He was the SE. Being cocky I said, bit big ain’t they old un. Looked at me, and said agree with yer son, buts it’s what the damn book says.
He then said, if we could dig them the same shape as a tulip bulb, they could be two thirds smaller. I said how’s that. He said it would distribute the load and pressure over two thirds a bigger area than that hole you have just dug. He walked away.
Have often thought about it. Try it on your tutor. Would appreciate any other comments, or views.
old un

r896neo · 5 May 2010

i'd prefer not to be the joker in there with the shovel undermining the 6ft bank of earth!

hotrod · 6 May 2010

theoldun said:
He then said, if we could dig them the same shape as a tulip bulb, they could be two thirds smaller. I said how’s that. He said it would distribute the load and pressure over two thirds a bigger area than that hole you have just dug. He walked away.
Have often thought about it. Try it on your tutor. Would appreciate any other comments, or views.
old un

Oldun, he was probably referring to the pressure bulbs that relate to / occur in soil mechanics

We covered it on my degree but only very briefly. I'm sure one of the SE's could elaborate.

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Pad foundation sizing

hotrod

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