PT conc slab analysis without drawings
PT conc slab analysis without drawings
(OP)
I have a client who wants to put a large piece of equipment on a 2-way PT elevated slab in a hospital. The only information I have is an X-ray of the floor locating the strands.
Anyone have any ideas on how to proceed with an analysis?
I posted this in the PT forum also.
Thanks.
Anyone have any ideas on how to proceed with an analysis?
I posted this in the PT forum also.
Thanks.






RE: PT conc slab analysis without drawings
I do a lot of work on existing properties, but I refuse to modify or evaluate the capacity of an existing PT floor in absence of quality information. Perhaps I'm just not aggressive enough, but this is not a check I'd be prepared to undertake.
With any luck one of the PT experts we have around here will chime in and I'll learn a thing or two. Good luck with it!
RE: PT conc slab analysis without drawings
For a large piece of equipment I'd also be worried about punching shear, which you can check conservatively with less information.
I don't think you should be sticking your neck out on this one unless someone like Raft can tell you how and hold your hand. Good luck!
RE: PT conc slab analysis without drawings
If all avenues like this have failed, you can chip into the concrete to locate a strand and measure its diameter with calipers.
If you know the date of construction, you can assess the most probable GUTS of the strand.
An added issue that you must keep in mind is that if these are older strands before the extruded sheath was introduced, they almost certainly have some degree of water in them and corrosion and failure of wires and even whole starnds. Guaranteed. The water got into those type tendons during construction, even if it is in a dry environment in the finished building.
For a number of reasons, whoever used unbonded tendons in a hospital was not a very prudent engineer, in my opinion.
Curious - how much does the equipment weigh, and what is the bay size?
RE: PT conc slab analysis without drawings
How big is the equipment?
RE: PT conc slab analysis without drawings
RE: PT conc slab analysis without drawings
RE: PT conc slab analysis without drawings
No shop drawings though, but that was too much to ask I think.
Floor is designed for 200 psf (former x-ray storage), the equipment is 225PSF, but on a small footprint. So I need to do an analysis to see what we can get for load spread on the 2-way slab.
RE: PT conc slab analysis without drawings