Prestressed Double Tee Floor
Prestressed Double Tee Floor
(OP)
I am trying to evaluate (for proposed loading) 14” double tee floor sections on an existing laboratory built in 1965. A Louisville,KY local firm, Dolt & Dew (which is out of business) fabricated them. I have searched the load tables in the 1971 PCI handbook but cannot seem to find any double tees that match the dimensions that we have. I have the shop drawings but the design loading/strand details etc. are not specified. The width is 5'-8",the center to center of the webs is 34" and the end to center of webs is 17". Can anyone suggest where I might find these very old load tables? Thank you.





RE: Prestressed Double Tee Floor
The only thing you can do is either so some sort of exposure of the tendons (which I wouldn't recommend for fear of damaging them), or some type of X-ray system (which I'm not familiar with) or a load test.
I once did a load test for some double tees used on a grandstand using water barrels and following ACI 318 and the IBC.
You would need to create some shoring system to alleviate the danger of the load test over-loading the tees to avoid a collapse. Deflection monitoring would be required to determine the elastic spring-back per ACI.
RE: Prestressed Double Tee Floor
Load testing would be the proper way to go for evaluation. I would not recommend using barrels as they do not allow sudden release of the load in the event of impending failure. I would construct a baffled pool with a plywood frame and a membrane to hold the water (6-mil poly works fine). You can build a safety feature into this that allows you to suddenly drop the load on the system in just a few seconds....critical for failure prevention.
RE: Prestressed Double Tee Floor
When you say "baffled pool" you are indicating a pool that is divided up into smaller pools so that when the framing members deflect, the water doesn't rush to midspan - correct?
RE: Prestressed Double Tee Floor
I have used this on relatively large load tests (40x40 bay in parking garage)...it works fine.