Instability Joint

RE: Instability Joint

HK — Wed, 25 Jan 2023 21:58:02 GMT

Thank you Abhishek for your immediate response.

RE: Instability Joint

Abhisek M — Wed, 25 Jan 2023 06:19:22 GMT

Please refer below wiki for detailed explanation.

Difference Between ELASTIC MAT and PLATE MAT

RE: Instability Joint

HK — Tue, 24 Jan 2023 18:39:32 GMT

Hi Abhishek, for this case I had considered plate Mat (since I had considered plates), could you please advise which is better suits either Elastic mat / plastic mat. when will be preferred to use Elastic mat.

RE: Instability Joint

HK — Tue, 24 Jan 2023 17:59:47 GMT

Thank you very much Abhishek for your reply & detailied clarification. I have tried and there is no warnings now.

RE: Instability Joint

Abhisek M — Tue, 24 Jan 2023 06:55:29 GMT

Hello HK,

I have 2 suggestions for your file.

1. As you have used tension compression spring in the model you should use Repeat Load instead of Load Combination.

How to convert a LOAD COMBINATION to a REPEAT LOAD

2. In the model you have used compression only spring in Y direction. This suggests if there is any tension in the support, the supports will be inactive. In your model due to lateral loads and vertical upward loads, a huge amout of tension is generated and the downward gravity load is not enough to suppress it resulting net tensile force in the support. As a result the whole structure is become unstable in certain load cases and combinations. You may either use NONE instead of compression only option and the file should run okay.

Or you should review the loads and try to match the boundary condition accordingly.