The output from the solution includes the Response Spectrum Calculation Summary. This table,
which is part of the printed output, lists the participation factors, mode coefficients (based on lowest
damping ratio), and the weight distribution for each mode. To obtain the response of each mode
(modal response), multiply the mode shape by the mode coefficient (based on lowest damping ratio).
You do this by retrieving the mode coefficient with the *GET command (Entity = MODE) and using
it as a scale factor in the SET command.If needed, you can retrieve the frequencies, participation factors, mode coefficients and effective
damping ratios with the *GET command (Entity = MODE).In addition to the above, the output from the solution also includes a DDAM Response Spectrum
Calculation Summary. This table, which is part of the printed output, lists the shock design value
and spectrum loading type for each mode.- Repeat St ep 3 to excite the structure along different directions if necessary. Note that solutions are not
written to the Jobname.RST file at this time. - Leave the SOLUTION processor.
Command(s):FINISH
GUI:Close the Solution menu.
NoteTo compute the effect of multiple spectra independently, see Running Multiple Spectrum
Analyses (p. 145).6.7.2. Step 4: Review the Results
Results from a DDAM analysis are written to the mode combination file Jobname.MCOM in the form
of POST1 commands. These commands calculate the overall response of the structure by combining
the maximum modal responses in some fashion (specified by one of the mode combination methods).
The overall response consists of the overall displacements (or velocities or accelerations). If element
result calculations were requested in the expansion pass and stored in the results file, the overall response
also includes the overall stresses (or stress velocities or stress accelerations), strains (or strain velocities
or strain accelerations), and reaction forces (or reaction force velocities or reaction force accelerations).
You can use POST1, the general postprocessor, to review the results. See St ep 4: Review the Results (p. 143)
for details about the post-processing.
6.7.3. Sample Input.
A sample input listing for a dynamics design analysis method (DDAM) spectrum analysis is shown below:
! Build the Model
/FILNAM,! Jobname
/TITLE,! Title
/PREP7! Enter PREP7
...
...! Generate model
...
FINISH
!
! Obtain the Modal Solution
/SOLU! Enter SOLUTION
ANTYPE, MODAL! Modal analysis
MODOPT, LANB! Block Lanczos methodRelease 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential informationSpectrum Analysis