Hi, In Fluid transient analysis, the capatured modal mass seems cannot be changed from the modal analysis. As a example below: TIME HISTORY LOAD CASES : ------------------------- Number of load cases analyzed : 1 Load case 1 - M1 Time history load file 1 : SUR Time History Load Type : 5. Imposed Force Number of TIH files of this type : 7 Analysis duration : 0.6000 s Analysis time step : 0.000010 s Output time step : 0.001000 s Number of time steps : 60000 Modal damping ratio : 0.0200 ZPA : No Captured modal mass (%) : 49.03 Added missing mass (%) : 0.00 I only get 49% of the captured modal mass, however, in my modal analysis, I got 90% as below: 39 1882.7112 0.001 0.0 0.0 0.0 0.365 0.000 0.047 0.137 40 1979.2090 0.001 0.0 0.0 0.0 0.121 0.381 0.489 0.330 Total captured modal mass (%) 92.535 85.607 92.108 90.083 Total system weight = 40.7 kg Note: Participation factors and captured modal mass apply only to Response Spectrum and Earthquake Time History load cases. Captured modal mass for other load types can be found in the analysis summary sub-report. The modal cut-off frequency was not reached. And in the note, it says that the capatured modal mass in the Modal analysis only applies to Response Spectrum and Earthquake Time History. My question is how can I increase the captured modal mass in Fluid Transient Analysis? Thanks. Fukun
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