Gap Spring Element

[Cholder]

I'm trying to use parallel springs to represent a support element that has increasing compressive stiffness with greater deflection. I've tried three springs with a zero gap and low stiffness in one, a small gap and a bit more stiffness in the second and a larger gap with more stiffness in the third spring. What I had expected was that the static gravity load step would work out the correct combined deflection but it is apparent that the static automatic gravity application step ignores the specified compression gaps.

| have also tried a triple multilinear element to represent the increasing stiffness with deflection. The parameters were set so the initial stiffness is very high for a small load, then a modest stiffening and a greater stiffness in the third element. In this case the initial dead load step failed to converge.

Suggestions on how to successfully model increasing compressive stiffness?

[seismosoft]

Dear Cholder,

Are you using the latest version of SeismoStruct, available from our website?

We have recently addressed some problems that had been identified by another user, though some additional inconsistencies may still be present (we are carrying out some additional checks on the gap_hook element).

Seismosoft Support

[Cholder]

I'm using version 5.0.4.

[Cholder]

I've just downloaded build 5 and now get better answers.