wrong modal result

[Edmond2000]

Dear STKO team:

I built a 3D frame model and used 'RCJonitModel3D' in it, but when I did time history analysis I found that the structure didn't seem to be connected together properly and the mode of vibration were clearly wrong as shown in the picture. I've tried adjusting the K(penalty) value of 'RCJonitModel3D' and using different constraint methods in the 'AnalysesCommand' but that doesn't work, how should I adjust the model so that the joints are connected correctly? Can you help me check the model? The model file is in the attachment. Thanks in advance.

Best wishes

[STKO Team]

It's because if you use the RCJoint and the rigid diaphragm together, you cannot use the transformation handler!
You should go with penalty.

And also, the analysis to setup the eigen should not have the "wipeAnalysis" otherwise it will be useless

[Edmond2000]

It's because if you use the RCJoint and the rigid diaphragm together, you cannot use the transformation handler!
You should go with penalty.

And also, the analysis to setup the eigen should not have the "wipeAnalysis" otherwise it will be useless

Dear STKO team:

Thanks very much for your help! Now the result is correct. This problem has troubled me for a long time.
But I still have a question: What order of magnitude is reasonable for the value of K in RCJointModel3D?

Best regards

[kesavapraba]

The penalty factor isn't fixed. It depends on the specific situation, including the units you're using and the properties of the material you're analyzing. A good starting point is to use a value similar to what you set for the penalty constraint handler in your analysis settings.
Also, you should check the order of the stiffness of load (moment) - displacement (rot) relationships assigned to Rx and Rz zeroLength materials. You can consider 3-4 order higher from the order of the zeroLength materials.

[Edmond2000]

The penalty factor isn't fixed. It depends on the specific situation, including the units you're using and the properties of the material you're analyzing. A good starting point is to use a value similar to what you set for the penalty constraint handler in your analysis settings.
Also, you should check the order of the stiffness of load (moment) - displacement (rot) relationships assigned to Rx and Rz zeroLength materials. You can consider 3-4 order higher from the order of the zeroLength materials.

Get it. I really appreciate your help.

[kesavapraba]

You are welcome