Dear Sir:

I am interested in modeling the loss of pre-stressing force in pre-stressed strands using ATENA 3D. I am modeling a pre-stressed concrete girder at the time of release followed by a shear test at 28 days. The variable material is being used to model the variation of concrete strength. Within the 28 days, the strands would experience some losses and would affect the stiffness of the girder for the shear test.

I understand that the pre-stressing force converts to a pre-strain that is applied to the strands. The strands are inactive in compression.

My understanding is that in order to model pre-stress losses, I would need to reduce the tensile strain in the strands. Give that the loads are incrementally applied in ATENA, I can only think of applying a negative pre-stressing force so that it would change to a negative applied strain and so it would reduce the existing tensile strain. Given that the strands are inactive in compression and a negative pre-stressing force would applying a compressive strain, I am not sure if this is the right way to do it.

I would appreciate it if you could recommend a way to model pre-stress losses.

Thank you,

Roya