Function
- Arrange the results of a free vibration analysis of the model (Natural periods of vibration, participating masses by vibration modes, etc.). Check Eigen vectors in a spreadsheet format table. Modal Direction Factor, Modal Participation Factor and Participation Vector have been added to the output so as to check various eigenvalue analysis results in a table.
- Check the mode shape normalized to unity (maximum eigenvector = 1).
- Table Tool in midas Civil offers a variety of powerful built-in functions. Refer to Usage of Table Tool for detail directions:
Call
From the main menu, select [Results] tab > [Type : Analysis result] > [Table] group > [Results Tables] > [Vibration Mode Shape]
Input
When you execute the Vibration Mode Shape Table function, the Records Activation Dialog will be displayed. Here, you can select the target nodes, elements, load conditions, eigenmodes, and other options. Once you have made your selections, click the OK button to generate the table. If you click Cancel, the table will be generated for all targets, which may take a significant amount of time depending on the case.
Please refer to the "Table Tool Usage" for instructions on how to use the Records Activation Dialog and refer to the Results Table for the generated table.
Using the Table Tool, you can examine the following data.
Table displaying the results of the eigenvalue analysis of the structure (Eigen Vector)
Table displaying the results of the eigenvalue analysis of the structure (Participation Vector)
Check the natural periods of vibration and the participating masses by vibration modes from the summary table of the Eigenvalue analysis results shown in the figure.
Check the natural periods of vibration and the participating masses by vibration modes from the summary table of the Eigenvalue analysis results shown in the figure.
Modal Participation Masses : Mass participation by modes
Modal Participation Factor : Modal Participation Factor
Modal Direction Factor : Modal effective mass ratio (Participation ratios by degrees of freedom on the basis of participation ratio of each mode being set at 100%)
Reselect 'Active by Eigenmode...' in Context Menu and assign the desired mode to check the natural vibration mode vectors.
Eigenvector : for each degree of freedom
Display eigenvectors in the unit consistent with the input mass unit.
Participation Vector : Eigenvector for each degree of freedom × Modal Participation Factor
Select ' Normalize by Max. Displ.' in Context Menu and assign the desired mode to check the mode shape normalized to unity.
Normalize by Max. Displ. : Display the Mode Shape normalized to unity (maximum eigenvector = 1).
In the old version, the Mode Shape was normalized to mass using the program's internal units, N & m. In V720, the Mode Shape is normalized to mass using units consistent with the input data.
(,
: Mode Shape Vector,
: Mass in the Input Unit)
Applicable to both Lumped Mass and Consistent Mass
.