- Select the variables to be operated on (corresponds to the IA,IB argument for the RPSD command).
- Select the type of PSD to be calculated (corresponds to the ITYPE argument for the RPSD command).
- Choose whether to calculate the response PSD with respect to the absolute value or relative to the
base (corresponds to the DATUM argument for the RPSD command). - Click OK to save your preferences and close the dialog box. The function rpsd(IA,IB,ITYPE,DATUM)
will be displayed in the expression area of the calculator. - Click Enter in the calculator portion of the variable viewer to start the evaluation.
When the evaluation is finished, the response PSD value is stored; the variable name is displayed in the
variable list area for further postprocessing.
8.8.1.2. Batch
Response PSDs and covariance values can be calculated for any results quantity using Jobname.RST
and Jobname.PSD from a random vibration analysis. The procedure for performing this calculation is
described in detail in Calculating Response PSDs in POST26 in the Structural Analysis Guide.
8.8.2. Generating a Response Spectrum
This feature allows you to generat e a displacement, velocity, or acceleration response spectrum from
a given displacement time-history. The response spectrum can then be specified in a spectrum analysis
to calculate the overall response of a structure.
8.8.2.1. Interactive
Generating a response spectrum requires two previously-defined variables: one containing frequency
values for the response spectrum (corresponding to the LFTAB argument for the RESP command), and
the other containing the displacement time-history (corresponding to the LDTAB argument for the
RESP command). The frequency values represent the abscissa of the response spectrum curve and the
frequencies of the one-degree-of-freedom oscillators used to generat e the response spectrum. You can
Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationThe Time-History Postprocessor (POST26)