# Manual Pile Spring definition (P-y) Point Springs

Question:

We would like to model soil springs using multi-linear point spring supports as follows –

Type 1 – lateral springs in X-direction that only acts in compression for both +/- X displacements (p-y curves @ all nodes)
Type 2 – axial spring in Z-direction that only acts in compression for -Z displacement and inactive for +Z displacement (tip resistance @ node 1 )
Type 3 – lateral springs in Y-direction only acts in compression for both +/- Y displacements (p-y curves @ all nodes)
Type 4 – axial springs in Z-direction that acts in tension for both +/- Z displacements (skin friction @ all nodes)
(**all displacement directions are in the global coordinate system)

The p-y curve is required to be modeled in by the following backbone curve :-
Ft.         Kip.
0.0        0.0
0.25     10.0
0.50     20.0
1.0       30.0
2.0       40.0
5.0      40.0

The axial spring for tip resistance is required to be modeled in by the following backbone curve:
Ft.        Kip.
0.0       0.0
0.25     100.0
0.50     200.0
1.0       300.0
2.0       400.0
5.0       400.0

The axial spring for skin friction is required to be modeled in by the following backbone curve:
Ft.         Kip.
0.0        0.0
0.25      1.0
0.50      2.0
1.0        3.0
2.0        4.0
5.0       4.0

Based on the above information, is it possible to define and then assign the springs in the model?

To define the pile with such behavior, the point spring supports could be used. Kindly refer the image below for details.
The springs for lateral direction (p-y curves).

Same feature could be used for global Y direction as well.
The input for tip of pile is as below. In this case, the spring would be unsymmetric to ensure no uplift resistance.

The input for skin friction at remaining nodes could be done as in the image below.
Creation date: 2/9/2018 12:21 AM      Updated: 5/22/2023 8:15 AM