Spring - Work Law - Non linear analysis

[OMRI2024]

Hi,

I’m working on the design of a pile and have defined the interface between the pile and the soil using springs with a force-displacement law. The type is set to a P in module in AQUA.

I then defined springs in the X and Y directions in SOFIMSHA, using the work law specified in AQUA.

After applying a force in the X direction at the center of the pile cap, I ran a non-linear analysis, but the system became unstable. However, when I ran a linear analysis, it worked well.

I also tried using PT in the definition of the work law, and while it worked correctly in both the X and Y directions, I noticed a reaction in the Z direction (although the values in the Z direction are very small).

Has anyone worked on a similar project and could provide feedback or share how they addressed this issue?

[JE170969]

Hi,
the work law describes only the behaviour for tension in a range between 0 and 20 mm. What if the displacements are higher or if there is compression?
=> Define a higher range between + and - 1000 mm. Then it will work.

Best regards,
Jost

[OMRI2024]

Hi,

In a nonlinear analysis, springs work only in tension (no compression).

For it to work, you need to set a behavior law that operates in both compression and tension, so that in a nonlinear analysis, the spring functions in a single direction, which is ideal for soil-structure interaction.