Hello everyone, I have a question regarding vertical displacement. So, I made a model in Abaqus for a prestressed beam as a 2D plane stress model for the concrete beam and a wire truss for the tendon. The concrete beam is a rectangular beam with 1200 mm of height, 600 mm of width, and 40000 mm of length. The tendon is a straight tendon that is located 360 mm under the concrete beam centroid.

I applied a time-dependent elastic modulus to the material property with the help of field variables and amplitude, where the elastic modulus will increase over time from 28 days to 365 days with an increment time of 0.1685 days. I made the step analysis as a Visco type. I also applied interaction between concrete beam and tendon as a constraint embedded region type, with tendon as the embedded region and the whole model as the host region.

I applied the self-weight of the beam as the body force. I also applied the tendon stress as a predefined field (type: stress), which applied to the tendon. I also applied the prestressed load as a predefined field with a field type that applied to the whole model. I chose displacement/rotation type for the boundary condition, where pinned support is located on the left bottom edge of the beam where U1 and U2 are ticked. Meanwhile, the roller support is located on the right bottom edge of the beam, where U2 is ticked. I mesh both the concrete beam and the tendon with the same size, which is 40 mm.

Lastly, I submit the job, and it is completed. I compared the result with the numerical calculation. The concrete stress, tendon stress, and prestress loss results are all the same as the numerical calculation results, but there is a problem with the vertical displacement. When I extracted the vertical displacement in the same x direction but a different y direction (top beam, center beam, tendon location, bottom beam), the results were all different, with the maximum difference between the top and bottom beams being 2.77%. As far as I know, the vertical displacement at each y-direction point in the same x-direction location should be the same.

Can anyone point out what I did wrong during the modeling so I can get the same results for the vertical displacement? Or maybe there is a particular reason why this phenomenon happened. Thank you so much for your help!

Abaqus ​​​​​​​