spurious vibrations
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ajetsonronald
- Posts: 2
- Joined: 15 Jul 2011, 09:48
spurious vibrations
The time history response of base moment and base shear contains spurious effects (numerical dispersion), the ground motion begins at 60 seconds but the response begins well before that with very high frequency. Could you help me fix the problem.
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seismosoft
- Posts: 1272
- Joined: 06 Jul 2007, 04:55
Re: spurious vibrations
Dear ajetsonronald,
We looked into the model you sent us, and have the following comments:
. the time-history curves are saved inside the *.spf files, hence no need to keep the separate time-history data files
. in order to define 40 seconds of zero dynamic loading you need only two points in your time-history curve - (0.0 ; 0.0) and (40.0 ; 0.0) - rather than the 4000 you are currently employing
. you then need to define two separate time-history stages, one from 0 to 40 seconds with e.g. 40 steps (i.e. dt=1 sec), and another from 40 to 150 seconds with 11000 steps (i.e. dt=0.01 sec)
. we did not find any spurious results
Hope the above helps.
Seismosoft Support
We looked into the model you sent us, and have the following comments:
. the time-history curves are saved inside the *.spf files, hence no need to keep the separate time-history data files
. in order to define 40 seconds of zero dynamic loading you need only two points in your time-history curve - (0.0 ; 0.0) and (40.0 ; 0.0) - rather than the 4000 you are currently employing
. you then need to define two separate time-history stages, one from 0 to 40 seconds with e.g. 40 steps (i.e. dt=1 sec), and another from 40 to 150 seconds with 11000 steps (i.e. dt=0.01 sec)
. we did not find any spurious results
Hope the above helps.
Seismosoft Support