strain too large

[mokiao]

Hi, anyone can help me?

I tried to add isolators under a structure in 3D. the structure itself is running well.
after I put one isolator under the building, then it came up with strain too large, and converge problem.

I model isolator using one zerolength element and zerolengthsection element.
the zerolengthsection element is using "section Bidirectional $lateral $Efs $Fy 0. 0.;" for x and y direction.
the zerolength element is using "uniaxialMaterial Elastic $hardness $b;" for x and y direction, too, and I fix remaining directions.

1.when I increase the $b value like 20lb/in, then it runs well, but when the $b value is changed to 0.5lb/in, then it had the problem "strain too large and can not converge". No matter how I changed the value of $Efs, the problem is still there.

2. So I tried to change the isolator using only one zerolength element "element zeroLength 1 2 3 -mat $Efs $Efs $ElasticM $ElasticM $ElasticM $ElasticM -dir 1 2 3 4 5 6;" However, if the $Efs is too small like 0.5lb/in, then there is the same problem "strain too large".

I fixed all other base nodes, only added one isolator, how come " the strain too large", and I plot the displacement from the unfinished recording, it is quite similar with the one before I put isolator.

anyone can take it look for me? Thank you in advance.

[mokiao]

I tried to test the model, for a zerolength spring, it is not allow to have the same displacement between these two nodes, is it right? which means the zerolength element must resist force and deformation? other wise, there will be warning "strain too large"?

can anyone think about it for me? I really appreciate your help.