Two Way Slab on Ground
Two Way Slab on Ground
(OP)
I have a situation where I have a client with a pool that is proposed to be supported on an 8" thick concrete slab. There is poor soil below the pool so the 8" thick slab has to be self supporting between rammed aggregate piers. Now, it seems like everything regarding slabs that we have at our office assumes the slabs are fixed to the columns. I don't have this situation and can't have this situation. Does anyone know of any way that I can perform an analysis without turning these into one way slabs (without a computer analysis program)?






RE: Two Way Slab on Ground
Sorry to be dating myself here...
Mike McCann
MMC Engineering
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RE: Two Way Slab on Ground
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RE: Two Way Slab on Ground
DaveAtkins
RE: Two Way Slab on Ground
RE: Two Way Slab on Ground
RE: Two Way Slab on Ground
In past projects, I have provided them with loading and a proposed slab thickness. They have returned suggestions for reinforcing as well as slab stresses. Obvioulsy you check there output, but they have a FE analsysis program set up for there piers. They model the piers as spring with differing stiffnesses extending from something close to infinite rigid at pier center line.
Just a suggestion to help validate your calculations
RE: Two Way Slab on Ground
1. DDM says that live load must be no greater than 2x dead load. I have a fluid load (a pool filled with water) which isn't really either a dead or live load, but I would consider to be more in line with a dead load situation seeing that they are always (well not always) combined with each other.
2. This part may seem like the dumb question part, but my moment transferred into the column would be zero correct? That was one of the points hanging me up because every example that I've ever seen has fixed supports, which makes sense because it's all cast concrete. With DDM I'm not restricted to fixed supports am I?
Thanks for all the replies so far!
RE: Two Way Slab on Ground
DaveAtkins
RE: Two Way Slab on Ground
Surely you can work out a BM diagram for a slab (any member) supported on knife edge supports! You learn that in 1st year university!
Doesn't the DDM make some assumptions about moments into supports?
RE: Two Way Slab on Ground
1. the live versus dead load limitations in the code are because of pattern loading - not really applicable in your case.
2. treat the columns as knife edge supports and this will be conservative.