Hello everyone
I am going to model some 2D steel moment frames and perform NTH analysis. The method of scaling ground motions in ASCE 7-16 (16.2.3.2) needs a maximum rotational spectrum (RotD100) for each pair of ground motions. As this method seems rational just for analyzing 3D models, is it necessary to do the same for 2d models? (contrary to the ASCE 7-10, ASCE 7-16 doesn't have separate section for scaling ground motions for 2D models)
Dear Shayan,
The section that you referenced is meant for scaling the selected acceleration record to maximum considered earthquake response spectrum. If we assumed that you have a 3 accelerations (2 horizontals [H1,H2] and 1 vertical) for the same event. You need to choose one acceleration in order to do a 2D study.
After you select the acceleration you can find the response spectrum of this acceleration. There is many software do this task and I recommend to use SeismoSingle. There is a free version for academic use.
After you get the response spectrum as values you can take those values into excel sheet and scale it to maximum considered earthquake spectrum for the site that you study.
Another fast and reliable approach can be used through PEER Library. This library include a huge amount of records with a plug-in scaling tool. You need to define your response spectrum and the tool will scale it automatically based on your required period.
Hope this help you enough to scale your records.
All the best,
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This videos will help you a lot
https://www.youtube.com/watch?v=2lC1wMq4c_w&list=PLzBZ3hmMnx1ItfMeO9aGQ5PnC65_TeTBv&index=13
https://www.youtube.com/watch?v=-Wwe4KQvnMk&list=PLzBZ3hmMnx1ItfMeO9aGQ5PnC65_TeTBv&index=14
PEER Library Address
https://ngawest2.berkeley.edu/
SeismoSignal
http://www.seismosoft.com/seismosignal
Dear Mohammed Masmoum
The procedure you just explained is the same as what ASCE 7-10 recommends. ASCE 7-16 explains that for the aim of scaling ground motions, first there should be a maximum direction rotational response spectrum (Rot D100) for each pair of ground motions. Then scaling should be perform according to median of all Rot D100s. I know how to scale ground motions based on what you said, the problem is, it is different from what ASCE 7-16 recommends (there is no separate section for 2D modelling).
Dear Shayan Safaei ,
To answer your question, you can get the maximum rotational spectrum (RotD100) from NGA-West 2 website if you follow this procedure.
More information about this issue can be found in the following article.
Article NGA-West2 Models for Ground Motion Directionality
I hope that will help.
All the best,
Dear Mohammed Masmoum
There are some conceptual problems.
1- Scaling based on maximum directional spectrum seems rational when analyzing 3D nonlinear models, not the 2D ones. In 2D models, we analyze the structure for each component of ground motion pairs separately, So speaking of RotD100 doesn't make sense.
2- PEER scales each pair of ground motion up to MCE spectrum which is so conservative because ASCE07-16 indicates that the average of all ground motion's maximum directional spectrums should be scald up to 90 percent of MCE.
I think for 2D structural models, it is proper to scale each ground motion based on its normal spectrum and there is no need to RotD100 (The same as what ASCE07-10 and FEMA P695 recommends).
Hi there,
I am looking for information on scaling using spectral matching and have found this question.
I hope that the answer is not too late, since a long time has passed.
When doing 2D analysis I choose the largest components for analysis. The ASCE 7-2016 is not clear, as you indicate in the comment.
Best regards
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