SOLVERS: Load (Spectral Base Excitation)

Description

Defines base excitation cases for the Spectral Response solver.

Factor vs Frequency/Period tables, together with specified direction vectors, are used to include a base excitation case in the analysis.

Before any spectral base excitation cases can be considered in the analysis, the Base Excitation option must be set under SOLVERS Home: Spectral Response.

The excitation case is defined via the following columns in the grid.

Include

If set, the spectral base excitation case is considered in the analysis and corresponding modal and combined spectral result cases become available in the results file.

If not set, the spectral base excitation case is skipped in the analysis.

Spectral Case Name

Specifies the name of the spectral base excitation case. This will be included in the result case name for all modes and combined spectral result cases stored in the result file.

Excitation

Specifies the type of the base excitation. This can be Base Acceleration, Base Velocity or Base Displacement.

The effective base excitation is the product of the direction vector and the spectral table.

Spectral Table

Specifies the Factor vs Frequency table.

The Factor Unit set in the tables must match the excitation type selected, unless the Factor Unit in the table is set to None, in which case it will match all the base excitation types. Base excitation using tables with Factor Unit set to None is not recommended because if the model units are scaled, it can change the excitation magnitude.

Factors X / Y / Z

Defines the magnitude and direction of the base excitation with respect to the global XYZ system.

The units of the direction vector are not specified, therefore it is recommended that the vector be used only as a direction vector, with magnitude of 1.0. The physical units will then reside with the spectral table. Using this approach guarantees that the model remains physically unchanged if the global units are changes.

Toolbar Functions

Insert row

Inserts a new row before the highlighted cell.

Add row

Adds a new row to the end of the list.

Delete selected rows

Deletes the highlighted rows.

Selections

Selects all, clears all, or inverts all spectral base excitation cases.