A. To generate a floor spectrum
To calculate the floor spectra from time history acceleration, use the following procedure.
This procedure should only be used if a time history load case is being solved by the analysis engine.
Note: The floor response spectrum command must immediately follow an analysis command. Therefore, it is helpful to select the corresponding analysis command prior to starting this procedure.
This command is used to specify the calculation of floor and/or joint spectra from time history results.
- Select the Generate Floor Spectrum tab.
- For every group and direction that is necessary:
- (Optional) Type frequency options to use for the spectra (all are optional inputs):
- (Optional) Type up to ten Damping Ratios to use as a ratio. (e.g., 3% damping is 0.03) One spectrum will be generated for each damping ratio for each global direction requested for each floor defined. The spectrum will be based on these damping ratios. Is not entered, the default of 5% (0.05) damping will be used as a single damping ratio.
- Check the Relative Acceleration? option if there is ground motion defined and you wan tthe spectrums based on the relative acceleration of the floor to the ground acceleration. Otherwise, the acceleration is assumed to be an absolute acceleration.
- (Optional) Select the print parameters as needed (both are optional):
- Select the Print Option you want to use.
- Click Add.