Today, I created a test model to compare external prestress of the cross-section using the Tendon module and cables in linear analysis. To do this, I used the
sysp command with
... beta 0 mue 0 sp 0 minr=1e-3 and
cs ... ics2 999. The prestress force was
6138*0.774 for both the Tendon and cable models. However, for the cable model, I used a factor of
241347/176470 for consider of elastic deformation .
The model is built as 3 beam which:
- beam 1: concrete beam prestressed by tendon sysp 1, so
- beam 2: concrete beam prestressed by tendon sysp 2, so
- beam 3: concrete beam prestressed cables as finite elements
I have attached the model with a
.gra file. The graphic in file are:
- Graphic 1: The elastic deformation Z of all three models is acceptable.
- Graphic 2: The elastic deformation X of the third model is slightly higher, which is normal due to elastic deformation of the beam.
- Graphic 3: The stresses in the tendon are similar, which is acceptable because the prestress force is very similar, but not identical (due to another input…).
- Graphic 4 and 5: The stresses of the concrete beam are completely wrong when the
dovalue is significant (beam 1).
The difference between beam 2 and beam 3 is acceptable, but concrete stresses in beam 1 are wrong. In my opinion, the problem is that AQB treats the tendon’s ungrounded duct area as negative, even when the duct is outside the section. I tried to find a solution to this issue in the AQB manual, but I was unsuccessful. Is it a bug or did I miss something?
I have also attached the model’s .dwg and .dat files for SOFiSTiK 2023.
Best regards, SB