Variables via SOFiPLUS-X

Hi, everyone.

There’s one troublesome situation that was tried to be solved by various options. A brief disclaimer: I’m using 2020 version of SOFiSTiK (don’t know whether this piece of info will be helpful or not :sweat_smile:)

So, the problem is related to variables. As you see (photos are below) the task was to create an “unusual” model of the extradosed bridge. The most problematic stage is creation of kind of “fin” (or “hump”, whatever) where the prestressed tendons are supposed to be implemented.

Watched some videos where the 2016-2017 versions, however, had been used I just repeated the same actions trying to link some points of cross section and specify variable (#ZF) to vertical coordinates. Next the values and rules of alteration for variable were set.

The result was inadequate: the only one value of variable specified in the tab “Cross section properties” had been applied to model of bridge… All the rest rules and values were neglected without any notification of errors or at least warnings during calculation of FE-model!

There were many attempts to fix that: various initial values (0, -0.35, etc.), using complete and incomplete list of placements during specifying the values and rules for variable, changing of rules, even testing the other types of solid CS (nonsense, but it failed too :face_with_peeking_eye:)

Dear colleagues, if you have any thoughts on problem or you’ve encountered with something similar, please share your solutions :pray:t4:


Hello Cyrill

In order to be able to help you properly, I need some more information. How are the tendons connected to the poles? How are the tendons prestressed? You must decide whether to use cable elements or tendon prestressing. The TEDDY offers a variety of different examples, maybe they will help you.

  • for external prestressing:

TEDDY > File > Examples > tendon > english > tendon1.dat

  • use of cable elements:

TEDDY > File > Examples > csm > english > optimize > e.g. csm21_equation_cable_stayed.dat
TEDDY > File > Examples > ase > english > geometric_nonl > …

The general workflow for the definition of the prestressing is explained within our online bridge design training.

If the examples don’t help you, please provide us with a simplified version of your project.
Overall this should be possible. We just have to find out what the problem is.

Best regards
Frederik Höller
Your SOFiSTiK Support Team

Dear Mr. Höller,

Thank you for your reply. I’m apologizing for postponing a message.

First and foremost I would like to answer your question about supporting system. The extradosed type of bridge span is complicated enough. And as it’s been discussed with colleagues it’s more likely to use cable elements but insert them into ducts in order to protect from direct interaction with concrete which is forming the most interesting part of the scheme – a fin which is supposed to be constructed by “cast-in-place” method (still unidentified clearly because of complexity of system).

Attachment of the cables to the elements of a cross section is similar to attachment of cables via deck and central wall as if it would have been a cable-stayed bridge.

But this perplex solution comes only to the prominent parts of the span (to the fins). Prestressing systems is used for sure and as the same as for the long-span bridges constructed by balanced cantilever method.

The post-tensed tendons should pass through the ducts in the upper (nearly to the piles) and in the lower parts (intermediate parts of span) of the cross section. Predominately in the ribs (as it’s seen in the image below).

The key problem is a lack of correct response to the actions I’ve undertaken in order to make the height of the rib variable. Whatever I have been trying, it’s still of the one height and not changing it.

Thank you again for support, I will try to work out something with the codes you have provided but will be highly appreciated for some other pieces of advice.

Best regards,