Product(s):	SACS
Version(s):	All.
Area:	PSI/Single Pile Analysis

Problem

A single pile analysis outputs half of compression capacity compared to results in PSI analysis as below:

PSI Listing File


Single Pile Analysis

Shouldn't we get the same capacity if we apply the same displacements and rotations at the top of the pile?

Solution

PSI uses the finite difference method for pile capacity calculation while Pile3D uses the finite element method which is supposed to be more accurate. Pile3D will very likely calculate larger pile deflections for the same pile loads compared to PSI. In this example, the pile deflection is being kept the same, Pile3D hence reports a smaller capacity than PSI, assuming all inputs to Pile3D are correct.