The Selected Base Excitation PropertyManager applies excitation to a restraint. If the restraint has more than one direction, you can select one direction at a time to apply the excitation. You can apply multiple selected base excitations.
The following types of restraints are not supported for selected base excitation: Symmetry, Hinge, On Cylindrical face, and On Spherical face.
The excitations you can apply depend on the study's type:
- For modal time history studies, you can define displacement, velocity, or acceleration selected base excitations as functions of time.
- For harmonic and random vibration studies, you can define displacement, velocity, or acceleration selected base excitations as functions of frequency.
- For response spectrum analysis studies, you can define selected base excitation in terms of a given displacement, velocity, or acceleration response spectrum.
The response spectrum contains the peak responses over time for a range of single-degree-of-freedom (SDOF) systems subjected to a particular base motion as a function of their natural frequency or vibration period. Each response spectrum curve corresponds to a particular modal damping ratio.
In a response spectrum analysis study, you can apply multiple response spectra definitions for uniform or selected base excitations. In case of multiple response spectra definitions, the total response is calculated by the square root of the sum of the squares of the individual responses.