Generate Floor Spectrum tab
Used to specify the calculation of floor and/or joint response spectrum when subjected to a time history loading. This information can be used in conjunction with equipment that will be supported by these floors and is often required by the equipment manufacturers.
The Floor Response Spectrum command must immediately follow an analysis command. That analysis can only contain a single time history load case. The groups of nodes used to define a floor must be defined prior to adding this command. Results from this analysis will be displayed in the Floor Spectrum table in the Postprocessing workflow.
|Floor Groups table||
Each row constitutes one floor which can have one or more floor groups assigned.
The resulting response spectra will be based on the collective responses of all the nodes in the selected groups.
|Lowest Frequency||Lowest frequency to be in the calculated spectrum. This value should be at least 0.01 Hz.|
|Highest Frequency||Highest frequency to be in the calculated spectrum.|
|Frequency Interval||The change in frequency values used for each interval calculation. The spectrum will be calculated at this interval from the Lowest Frequency to Highest Frequency specified.|
|Damping Ratios table||Up to ten damping values may be entered. One spectrum will be generated for each damping value for each global direction requested for each floor defined. The spectrum will be based on these modal damping ratios. Damping is specified as a fraction of one (that is, 3% damping should be entered as 0.03). The default is 0.05.|
|Relative Acceleration?||Select this option if there is ground motion defined and you want the spectrums to be based on the relative acceleration of the floor to the ground acceleration. Otherwise, absolute values are considered.|
|Print Time History Acceleration used?||Select this option to print the time history acceleration being used in each spectrum calculation.|
|Print Calculated Spectrum?||Select this option to print the calculated spectrum.|