Issue with hinge condition of boundary SARB

SOFiSTiK Teddy
1

Hi,
I’d like to ask someone more experienced than me to explain what’s happening here:

  1. When I set fix at SLN 19 it looks fine:

  2. But when I try to add DFIX parameter it creates additional constraints around 2 more edges (nothing other than dfix is changed)

Unfortunately I’m unable to put any images here.

Another thing is that I have some concerns about whether these constraints are put correctly. I’d like to assign hinges according to local coordinate systems of element and I’m wondering if it’s a correct approach.

The thing is that the whole model is ultimately parametrized - that’s why the FIX command is what I’d like to use.

Szymon

2

Hard to say without some code, so I’ll take a wild guess.

You can either define your SARs and boundary conditions by:

  • Defining SAR/SARB/SLNB with coordinates in one go.
    Then DFIX creates a new boundary line (for your SAR) with the specified distance and couples it to the SAR boundary.
    That’s how you get the desired eccentricity/lever arm.

  • Define SPTs, define SLNs referencing the previously defined SPTs and finally define SARs by referencing the SLNs
    Then you can control exactly which line/boundary is connected to what.

Sounds like you are using the first approach and you get the desired distance (but aren’t expecting it).
If you want more control, use the second approach. Then you define all the boundaries, excentricities and couplings yourself.

3

Thank you for response.

I’m using the second approach - defining SARs by referencing SLNs:
SAR 21 GRP 82 T #TWFP1P MNO 1 MCTL 1 QREF BELO
SARB OUT NL 17 FIX PY //DFIX 0.05
SARB OUT NL 262
SARB OUT NL 263
SARB OUT NL 264
IF #PS==1
SARS CA #CA_P1P CL #CL_P1P GRP 820
ENDIF

Right now I even got one coupling on the SLN i didn’t put “FIX” after…

Some areas share the same SLNs and that’s why I’d like to create couplings between these SARs edges.
But even tough I reffer to the same SLNs, program still produces some new on the intersection of the SAR

4

It may be some kind of geometry sensitiveness.
I’ve changed geometry a little and unwanted couplings are gone, but when trying to use DFIX with some gap distance, it still results in couplings on the outline of SAR.

5

My approach would be the following:

  • If there’s a gap, model two SLNs (one for each border)
  • Connect the SLN’s using SLNS (I prefer stiff springs over fixed couplings)
  • If you don’t want a gap at a boundary, you can model two SLNs on top of each other (sometimes easier from a programming/syntax aspect)