How does a zero length element know what direction compression or tension is in?

[andred]

Hi there,

I'm trying to use a zero length element with the QzSimple1 material, the idea being to represent a foundation spring (i.e. Winkler foundation). The QzSimple1 material should only provide capacity in compression, but how does the zero length element define what direction compression is in? Because in my thinking, it will always appear to elongate, as one node is just directly on top of the other to begin with.

Any help appreciated, thanks!

[RobinZeng]

You can refer to the detailed definition of ZeroLength element, https://opensees.berkeley.edu/wiki/inde ... th_Element
, the direction of Zerolength element is defined orient vectors. About the compression direction of the material, you can build a simple model with only 1 zerolength model to check if the direction is what you want.

[mhscott]

The explanations in this post should help: https://portwooddigital.com/2022/05/08/switching-sides/