SAP2000 cables deforming f'd up 1

[kauri]

Hey,

I'm making a SAP2000 model for a cable stay bridge. This keeps happening:

Currently I've defined the self-weight as 0 in the loading pattern. Still, if I change the cable diameter from 0.1m to 10m, this happens:

Or if I define the self-weight as 1:

I think the question is self explanatory Cheers

Let me know if I need to provide more info.

 

[kauri]

Another thing I should mention is the analysis details don't show any errors, all OK. The cables are taking axial load as expected.

SAP file attached.

 

[canwesteng]

Any cables taking axial compressive load?

 

[Agent666]

Check that it's not a graphical scale issue, sometimes the scale at which deflections are shown can be too large and deflections look out of wack, try turn off auto scaling and set it to 1, does it still look the same? Work your way up until you see the deflections.

Correct area and E for the cables?

 

[kauri]

Thanks for the ideas guys! I opened up SAP to check your suggestions but it now looks like this:

...
Not a thing changed since yesterday! So maybe it was just a graphical glitch, but it's happened on 3 separate models so I don't know.. UGH! Is it common for SAP to experience graphical glitches?

 

[JoshPlumSE]

Any time a program starts giving really weird behavior, it's a good idea to exit out of the program completely and then re-start. It's kind of like the old days of Windows when you had to constantly shut the computer down and re-start.

What happens is that the memory state of the program can get corrupted. While this rarely happens with the operating systems anymore (at least compared to Win 3.1 / Win 95), individual programs can still have their memory go south.

I've seen this happen with many programs recently.... BlueBeam, RISA, ETABs. It even happened for me while using Excel this week! In each instance shutting down the program completely and then re-starting it fixed the problem.

 

[UcfSE]

From your SAP2000 file, you're running a linear static analysis with cable elements. Cable elements are formulated nonlinear, so you must use a nonlinear analysis. P-Delta is preferred. In some cases using the large displacement analysis with cable elements can help. They are very sensitive so you have to play with them a bit. Your graphics issue is not uncommon when analyzing nonlinear components with a linear analysis.