Storage Tank Slab Opening
Storage Tank Slab Opening
(OP)
I need a bit of guidance in tackling my most recent work assignment. I have a RC rectangular box storage tank (60-ft long and 20-ft wide and 13-ft deep) that contains sulfur. The storage tank is located in a refinery. I need to punch a hole (18-inches x 30-inches) in the top slab (13-inches thick with No. 6 @ 8" e.f. e.w.) to permit the installation of a submersible pump. There is no additional load on the top slab as top of slab is 6-inches above grade.
I am interested in methods of analysis (ACI 318?) to determine if the existing slab will support the load from the new pump (approx. 4.5 kips dead weight and 2.5 kips operating weight) and possible retrofits to the slab in the area of the new opening to ensure a safe and reliable design (already plan on sealing cut concrete with chemical resistant epoxy paint). My gut tells me there is plenty of flexural and shear capacity in the two way slab.
Any other pointers will also be appreciated.
I am interested in methods of analysis (ACI 318?) to determine if the existing slab will support the load from the new pump (approx. 4.5 kips dead weight and 2.5 kips operating weight) and possible retrofits to the slab in the area of the new opening to ensure a safe and reliable design (already plan on sealing cut concrete with chemical resistant epoxy paint). My gut tells me there is plenty of flexural and shear capacity in the two way slab.
Any other pointers will also be appreciated.





RE: Storage Tank Slab Opening
Keep the hole, if you can, approximately 10' from the exterior wall; this will take you out of regions of -ve moment. Have the long dimension of the new opening parallel to the 20' span.
You can check the reinforcing cut, likely a max of 3-#6 bars... The #6@8 T&BEW seems like real overkill but you can do the sums since I don't know what the loading is. If necessary to reinforce the slab because of the opening, then carbon fibre and epoxy might be in order. Check to see that there is no adverse reaction of the concrete and repair to sulphur... there shouldn't be... but check.
RE: Storage Tank Slab Opening
So I would model it up with finite elements. Follow dik's advice and keep the hole out of the center of the slab. Model the hole one or two bar spacings larger than the actual hole, and you will almost certainly not need to reinforce it.
First thing you need to do is determine is whether or not a truck could drive onto the slab. Whenever I have a tank cover 6 inches above grade, I design for HS20.
RE: Storage Tank Slab Opening
Dik
RE: Storage Tank Slab Opening
I agree with Dik, so long as you have enough experience with these situations that you trust your judgement. My advice was based on the assumption that this was the first time you were looking at this type of thing.
RE: Storage Tank Slab Opening
Dik
RE: Storage Tank Slab Opening
RE: Storage Tank Slab Opening
You can analyze an opening all you want with shiny tools, but you're at the mercy of as-built conditions. Plus when an opening is saw cut, the blade tends to overcut beyond your specified size.
RE: Storage Tank Slab Opening