precast double tee roof

[structSU10]

I have an existing building from 1963 that has precast double tee construction. There are no shop drawings for the double tees, and we want to know whether it was typical to have prestressing tendons, and whether or not they would be draped or straight. Anyone have historical information on double tees?

 

[dik]

It is very likely that they were pretensioned. In addition to straight strand, the strands were often 'harped', that is, pulled down to provide greater +ve moment capacity.

Dik

 

[msquared48]

I agree with the "harped" during that timeframe...

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[BAretired]

Sometimes the strands were harped at midpoint. Sometimes they were harped twice at about the third points. Sometimes straight strands were used with bond breaker near the ends. The goal was to maximize positive moment capacity at midspan while minimizing initial stresses in the end regions.

If you have no shop drawings, you will likely have to X-ray one or two ribs to find out what was done in your case.

BA