A dynamic analysis of geotechnical structures loaded by ground motion. It either accepts user-defined accelerograms or generates ground motion histories compatible with the specified response spectrum. The program outputs the evolution of displacements, stresses, internal forces, and other mechanical quantities and summarizes their maximum values. It also performs modal analysis to acquire eigenfrequencies and eigenmodes of the system for setting the material damping. Click for more details. This is an add-on and requires the GEO5 FEM program.