Dear Sir,

Thanks for your response. I sent an e-mail description with a sketch to the following e-mail address:

cervenka@cervenka.cz

I copied my question below:

I am trying to model the release of the prestressing strands (cutting the strands so the force is transferred to the concrete) at one stage followed by the application of a concentrated load (shear test) at later stages.

The strands are released at f'ci (release strength of ~6.5 ksi). I used the Bigaj model to model the slip of strands at release. For the next stage, loading in shear, the concrete has developed its 28-day strength (13 ksi). At this stage, the bond model should be a function of the new concrete strength. The issue was that I could not specify variable material properties for the bond (as a function of the load stage).

For release, the girder is sitting on slabs and allowed to camber up (no support plates modeled). For the shear test, the girder is sitting on two elastomeric bearing pads and load is applied using a loading plate. (these support conditions are different from the support conditions at "release"; hence, I am using the construction process to add the bearing plates in).

I will send you a sketch as well.

Thank you,

Roya