Cable-stayed bridge

[martihol]

Hi! I`m analyzing a cable-stayed bridge during earthquake excitation. When I just try to apply gravity in a static analysis, the message "Unable to apply the entire permanent load" appears. I suspect something is wrong with the stay-cables, so my questions are:

1) How would you suggest modeling cables? So far I`ve used 10 elfrm elements per cable with appropriate EA,EI,GJ,m.
2) How can I include pretension in the cables?

I`ve tried searching this forum for "cable", but it didn`t help me. I could send the model to you, if that is more convenient?

Thank you!

Martin H.

[ricardomonteiro]

Hi martihol,
You can try to browse the forum looking for tension-only bracing. There has been some discussion around that.. Maybe it can be helpful..

[martihol]

Thanks for your reply, Ricardo, but neither the help files or forum threads has helped me, except I read that pretension could be modeled by permanent load (a rather cumbersome way of applying it, since you cannot apply load in the direction of the cable, only as x,y,z components).

I`ve also tried to simplify the model by removing rigid links and using only one tenision element per cable. Still, I could not apply the permanent gravity load.

Anyway, is there anyone here how would like to check out my model? I would very much appreciate any help!

[seismosoft]

Martin,

I am not sure we will manage to overcome the difficulty you report, but, if you send us an as simplified as possible version of the model, we will certainly try to look into it.

Seismosoft Support

[martihol]

Dear Seismosoft Support,

thanks for having a look at my model, I`ve sent it to you by e-mail now.

Martin