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?
Answer: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).
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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.
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The input for skin friction at remaining nodes could be done as in the image below.
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