Pseudo static acceleration

In PLAXIS 2D and PLAXIS 3D a pseudo static acceleration can be defined per phase in the Model Conditions > PseudoStatic option in the Model explorer:

Figure 1. The PseudoStatic option in the Model explorer

By activating the PseudoStatic option in a phase, and specifying the acceleration value in at least one of the components, these pseudo static accelerations will be activated in the calculation. The input values of the x- and y-acceleration (and z-acceleration) for 3D components are expressed in terms of the normal gravity acceleration g.

Model response

When e.g. a positive vertical pseudostatic acceleration is applied, the model responds analogue to objects in an elevator that accelerates in an upwards motion. The objects inside the elevator tend to feel as if a vertical force in a downwards direction is applied to them. This is the same behaviour that can be seen in a pseudo-static calculation: with a positive vertical pseudostatic acceleration, the free boundary of the model will show behaviour that this free boundary has displacements in a downward direction. This is the opposite direction of the specified pseudo-static acceleration.
For horizontally applied pseudo static accelerations the model responds in a similar way.