Modal Analysis: Mass Participation

MarcosBeier — Thu, 05 May 2022 14:54:14 GMT

Current Revision posted to LARS | LEAP | OpenBridge | OpenTunnel | RM Wiki by MarcosBeier on 5/5/2022 2:54:14 PM

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 Factor (CEMPF) in each direction that is used to indicate up to how many modes should the user go. In general, the most important are the natural frequencies, the lowest, with the most effective mass participation value; tough, for the analysis of bridge structures users usually need to get up to at least 90% Cumulative Mass Participation Factors for the directions considered important. Therefore, it is an interactive solution and a user engineering judgment of approximately how many eigenvalues are necessary for receiving the level of mass participation in each direction

If the default * file name is used in the Action Eigen in the Stage, for the output of mass participation, the user just has to search in the eigen.lst results report list file for a paragraph like the one shown in the image below. In the example below, only 10 modes would be good enough for both longitudinal and lateral directions but not for the vertical direction.

Additionally, the tolerance value for determining the accuracy of the calculated eigenvalues and the Modal Analysis methods, Eigen or Ritz, are specified in the Recalculate Analyzer pad in the menu at Advanced Options \ Dynamics.

More info at the link and the training 5 for Seismic:

communities.bentley.com/.../modal-analysis-eigenvalues

Tags: OBD, RM, MASS PARTICIPATION, effective mass participation, ritz, OpenBridge Designer, mass participation factors, RM Bridge, cumulative mass participation, modal analysis

Modal Analysis: Mass Participation

MarcosBeier — Tue, 26 Apr 2022 16:51:05 GMT

Revision 4 posted to LARS | LEAP | OpenBridge | OpenTunnel | RM Wiki by MarcosBeier on 4/26/2022 4:51:05 PM

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 Mass Participation in each direction that is used to indicate up to where should the user go. In general, the most important is the natural frequencies, the lowest, with the most m*** participation value; tough, for the analysis of bridge structures users usually need to get up to at least 90% Mass Participation Factors for the important directions. Therefore, it is an interactive solution and a user engineering judgment of approximately how many eigenvalues are necessary for receiving the level of mass participation in each direction

More info at the link and the training 5 for Seismic:

communities.bentley.com/.../modal-analysis-eigenvalues

Tags: OBD, RM, MASS PARTICIPATION, ritz, OpenBridge Designer, mass participation factors, RM Bridge, modal analysis

Modal Analysis: Mass Participation

MarcosBeier — Tue, 26 Apr 2022 16:41:57 GMT

Revision 3 posted to LARS | LEAP | OpenBridge | OpenTunnel | RM Wiki by MarcosBeier on 4/26/2022 4:41:57 PM

Tags: OBD, RM, MASS PARTICIPATION, ritz, OpenBridge Designer, mass participation factors, RM Bridge, modal analysis

Modal Analysis: Mass Participation

MarcosBeier — Tue, 26 Apr 2022 16:41:22 GMT

Revision 2 posted to LARS | LEAP | OpenBridge | OpenTunnel | RM Wiki by MarcosBeier on 4/26/2022 4:41:22 PM

Tags: OBD, RM, MASS PARTICIPATION, ritz, OpenBridge Designer, mass participation factors, RM Bridge, modal analysis

Modal Analysis: Mass Participation

MarcosBeier — Tue, 26 Apr 2022 16:32:41 GMT

Revision 1 posted to LARS | LEAP | OpenBridge | OpenTunnel | RM Wiki by MarcosBeier on 4/26/2022 4:32:41 PM

Additionally, the tolerance value for determining the accuracy of the calculated eigenvalues is specified in the Recalculation pad in the menu Extras \ Dynamic.

Tags: OBD, RM, MASS PARTICIPATION, OpenBridge Designer, mass participation factors, RM Bridge, modal analysis