Old Double tee Roof 4 ft tees, 2" stems

[alfred]

Roof framing is 4 foot wide double tees, stems at 2'-0 with 1' cantilever flanges. stem thickness only 2" at bottom with slight taper upward. Building is in Atlanta GA built in 1967. Tee depth is 12" overall with 1 1/2" top flange no topping. Span is 40'. Any ideas on allowable loads?

 

[Ingenuity]

Here is link to PCI Design Handbook load tables: Link

From PCI 1st Edition (dated 1971) they have 4DT14 which is 14" deep but no 12" as you require:

Regardless, you will need to get info on the prestress content, so some semi-destructive field work will be required if you cannot locate the original drawings.

 

[Ingenuity]

Here is a link to a PCI Paper entitled: "The legacy and future of an American icon: The precast, prestressed concrete double tee" by Nasser, Madros et al., dated 2015: Link

There is a brief historical discussion of the 4DT12: