Modal Analysis: Eigenvalues

The calculation of Eigenvalues is the first step in many dynamic calculations. Despite it involves advanced structural engineering concepts not always studied in deep in some civil engineering courses it is quite simple to do it in RM Bridge within OpenBridge Designer.

Since the Modal Analysis is generally a good indication of the model behavior it is also used just to check the structure. Therefore, as shown below, now the user has an option to automatically include it in the Structure Check when using the Recalculate Modeler and going from the Modeler to the Analyzer.

Stage

Note that the user defines another Schedule name with a specific Stage for the Modal Analysis and the load case where all defined masses will be accounted for the stiffness that will be calculated based on all the structural input. We still suggest using the default method for more specific analysis with partial or deactivated elements.

More information can be found at the links below:

Mass Participation factors:

Modal Analysis: Mass Participation

In the Modal Analysis user has the objective of obtaining the frequencies and shapes of each mode. As the number of eigenvalues to be calculated has to be given it is the Cumulative Effective Mass Participation…

Training 5 for Seismic:

5. Earthquake - Response Spectrum

The option 5. in the RM Bridge Enterprise Training Examples is the Earthquake that has the datasets and a description document for the seismic analysis of a three span bridge using the response spectrum…