Need help identifying prestressed concrete beam in residential basement (sketch)

[TroyD]

I am evaluating a SFD for excess deflection in the main floor framing. This residence has a in-ground pool in the basement. A pair of prestressed concrete beams span above the pool, the full length of the dwelling, approx. 52 ft. See attached sketch. Can someone tell me what type of prestressed beam this is? Should I call it a "single-tee"? It seems like a DOT type bridge beam, minus the deck. I suspect it had camber in it when the beam was originally placed, but has leveled out, causing 2" deflection in the main floor above. Any info is appreciated.

 

[dhengr]

TroyD:
Check with the precasters around the Twin Cities, or your immediate area, and see if they supplied those beams to that address, at that time. That shouldn’t be too tough for them to check, if they want to be a little helpful.

 

[Ingenuity]

What is the vintage of this structure?

Back in the 1950's (before single, quad and double tees evolved) there were 'keystone joists' by Nitterhouse Precast in PA. They were available in both reinforced and prestressed concrete.

The above dimensions do not tally with your sketch, but it may be a starting point if you reach out to local precasters.

 

[TroyD]

Thank you dhengr and Ingenuity. Owners say the house was built early 80's, but I think this concrete beam might have been added later...maybe they lifted/moved the house to place it?? The basement poured walls appear newer then the rest of the dwelling. The main floor framing is a cobbled mess. Unconventional framing methods galore. Inadequate trimmer studs, crushing sill plates, no blocking in joist spaces at concentrated loads. And significant 2"+ sag in the center of the main floor. I will reach out to Wells Concrete Products, in Wells, MN.