Singular Stiffness Matrix Error with Cable Stayed Bridge

Hi All,

I am having problems with supports resulting in an error when analyzing a Cable Stayed Bridge (a 'Singular Stiffness Matrix' on the Analyze component).

The strange thing is that I can get the model working by using different points (the points where the cables connect to the pylon) as the supports, however by using different points the model is obviously wrong.

I have uploaded a annotated file highlighting this area of the model. Any help would be greatly appreciated :)

Thanks

Ravi

Attachments:

CableStayedBridge_wrongsupports.gh, 45 KB

Replies to This Discussion

Permalink Reply by Karamba3D on October 23, 2014 at 1:06am

Hi Ravi,

I think your cables are not correctly attached to the pylon. This makes them float around when you remove the surplus supports.

The second thing is, that the supports at the endpoints of the bridge do not constrain all rigid body modes of the structure (it can e.g. Tx, Ty, Ry).

In order to check a structure for rigid body modes you can use the EigenModes component (see attached file).

Best,

Clemens

Attachments:

CableStayedBridge_wrongsupports_CP.gh, 38 KB

Permalink Reply by Ravi B on October 23, 2014 at 5:21am

Hi Clemens,

Thank you so much for the prompt reply! You are right, the top of the pylon was not divided into a number of smaller beams, but was a continuous one. After fixing that my model works a charm!

I have also adjusted my endpoint support conditions, thanks for the tip!

Kind Regards

Ravi

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