Angie,
We talked a bit offline, but I'll repeat a few things for the group hoping it sparks some additional discussion.
Foothills has dealt with it a few times on a small scale. The most pronounced one involved post-tensioning in an upper deck overhang. I'd have to go back in our archives to remember the specifics of how we handled it, but you can see in the attached photo the PT heads exposed. I recall that we thought about a few things: (1) level of certainty that the grout installed into the duct was consistent enough to hold the post-tensioning and (2) what would happen if the PT bar released all of its energy at once. Anyway, we could discuss your specific application and see if there are any similarities.
Demo of post-tensioned structures is not very widespread as the technology isn't that old - not too many bridges/bridge components being demoed that have it. I don't think there are too many past projects to draw experience from.
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Reuben Zylstra P.E., M.ASCE
Principal Engineer / Partner
Foothills Bridge Co
Boulder CO
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