Tendon grouting stage impact

SOFiSTiK Teddy
1

Hi, I’m trying to understand what Sofistik does under the hood regarding tendon grouting. I’ve looked at the documentation but can’t seem to find where the difference in the stages is explained.

I am referring to this line in Teddy’s Tendon program (after creating the dutc geometry):

cs 31 60 //CS installation and grouting stages, optional a removal stage

The above line instructs the progral that the tendons are installed at cs 31, and grouted at cs 60. Which makese sense.

My question is what does this effect in the model. Are the tendon stresses then calculated based on unbonded tendons beteen stages 31 and 60, and then as bonded tendons after stage 60? If so, how are these stressess calculated (I’d like to view the calcs and see what’s the difference to aid my understanding too).

If anyone can point me to the correct manual or some other example/document that would be greatly appreciated.

2

Yes
if you add load between those CS it shouldn’t cause stress change in tendon.
It also changes the way section ultimate capacity is calculated since unbonded tendons dont act as reinforcement, but bonded do.

3

My question is what does this effect in the model. Are the tendon stresses then calculated based on unbonded tendons beteen stages 31 and 60, and then as bonded tendons after stage 60?

If you grout at construction stage CS 60, the tendons become bonded at CS 60.
This means that in the subsequent analysis stages, the tendon forces are treated as bonded AT forces starting from CS 60, not from the stages after it.

Because the grouting is activated at stage 60, the structural system changes at that exact stage — including:

  • the weight of grout,

  • changes in section properties,

  • altered neutral axes (zₛ) to which internal forces and bending moments refer.

To see these effects directly inside the CSM run, you can add the following block after your existing CSM command:

+prog csm urs:43.1
head
ctrl file “chks”
sele beam 100035 x 0
end
+apply $(name)_chks.dat

This produces an additional output file containing internal checks during the construction stage run.
It will list:

  • stresses at each CS stage,

  • section properties actually used (including zₛ),

  • internal forces for each element during the CS process.

Important Note on BEAM vs QUAD Elements

For BEAM elements, there is no difference in the resulting bending moments between:

  • the stage of stressing, and

  • the stage of grouting.

However, for QUAD elements, the grouting stage does change the bending moments

4

Important Note on BEAM vs QUAD Elements

For BEAM elements, there is no difference in the resulting bending moments between:

  • the stage of stressing, and
  • the stage of grouting.

However, for QUAD elements, the grouting stage does change the bending moments

Why there are differences between beam and quad? Which one conforms to actual condition?

5

Q1: Why there are differences between beam and quad?

A1: not implemented

Q2: Which one conforms to actual condition

A2: QUADs