PISA, an acronym for Program for Incremental Stress Analysis, is a finite element program developed for analyzing deformation of geotechnical structures.

What Can PISA Analyze?

PISA is a solid deformation modeling program based on the displacement finite element method. It can analyze any solid provided that the mechanical behaviour can be described by one of the available material models. For example, the program can analyze deformation of steel using the linear elastic model, provided that the material behaves in a linear elastic manner. Soil and rock are materials with complex behaviour. PISA has a variety of material models to analyze soil and rock deformations.

Developed mainly for geotechnical applications, PISA has many features which are essential in analyzing a geotechnical structure. PISA can be used to model dam construction where the structure is built in stages. It can be used to model excavations such as those for a tunnel or building foundation. The geometries of these structures are continuously changing and therefore require the addition or deletion of elements during the analysis. These are called geometrically altered structures.

Since soil deformation is dependent on effective stresses, PISA can perform effective and total stress analyses in fully drained or undrained conditions. A variety of material models, such as linear and nonlinear elastic, plastic and critical state models are available for modeling complex behaviour of soils. PISA is a two dimensional program which means that the three dimensional reality must be simplified assuming plane strain, plane stress or axisymmetric conditions. Time dependent creep deformation can be analyzed using PISA.

Hardware and Software Requirements

To use PISA, it is necessary to have a 486 or later computer with Microsoft Windows 3.1 or later installed. PISA is developed to make use of the latest technology in computers. It is a 32-bit program which delivers high performance in computation and graphics. PISA operates in Windows 95, Windows NT, or Windows 3.1 with a Win32s extension.

In terms of hardware, a minimum hard disk space of 3 MB is required to installed the program and another 10 to 20 MB of hard disk space, depending on the size of the problem being analyzed, is needed for program execution. The computer should have a minimum of 8 MB RAM, but 20 MB of RAM or more is preferred. More RAM is required for larger problems and it will also improve program execution speed.

Program Information

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