Mr.Ziad, I suggest you to identify pile elements that is known with x, y, z coordinates and collect both displacements and stresses from these points within the elements.. ok all the best..

Dear Mr. Ziad El Hachem

P-y curves are plotted for definite depths (e.g. 1.0, 2.0, 3.0 m depth ,etc.)

For your case, in order to draw the P-y curve, you need lateral displacement (y) versus Soil Resistance (P).

My understanding is that you use volume cylindrical element in your simulation for the pile.

The easiest way -to obtain the straining actions and displacement- is as follows:

First, you can use a dummy beam element. Use a beam element of the same dimensional properties of the pile volume element. Such beam should include the same dimensions, its local axes should follow that of the volume element (in case of non-circular pile e.g. barrette or else) and use small value for the Elastic modulus compared to that used for the volume element (in order to avoid duplication of stiffness)

e.g. if you use for volume element properties E=30 GPa, use it for the dummy beam = 30 GPa/10^6 = 30 KPa

Second, for the lateral displacement:

For the Dummy beam you can easily extract the displacement values directly and get a table the define the displacement versus elevation (Z) that can be sorted from ascendingly.

Third for Soil Resistance:

You can extract the shear force easily for the dummy beam. Shear force should be multiplied by (10^6) -that we previously divided by earlier- in order to obtain real values not the dummy's.

Then conduct the differentiation of the shear force acting with respect to the pile length to evaluate the required Soil resistance (P).

P = dV/dx where P is soil resistance (kN/m), V is shear force (kN) and x is the pile unit length.

Then the soil resistance at the target depth is drawn against the corresponding deflection (y) extracted from the Second point to plot the required P-y curves.

Good Luck!