Maximum Direction Ground Motion

[Kirkaguel]

One of the requirements of ASCE 7-16 ground motion for response history analysis is that it should use the maximum directon ordinates of which in the case of PEER online scaling program is RotD100 which I believe Seismoselect also has this option, my question is when linking to PEER ground motion database and selecting the component definition, is the output ground motion already rotated to the maximum direction?

This is the limitation of PEER online scaling the selected ground motions are not scaled and not rotated to maximum direction. Is this capability automatic in Seismoselect?

[seismosoft]

As you correctly pointed out, the PEER database features only the RotD50 intensity measures and spectra. We are currently trying to find a way to automatically scale the RotD50 parameters to RotD100, so that to be compatible to ASCE 7-16 (and other codes), however this is by no means straightforward.
Note that the ESM database has the RotD100 parameters stored and also features more than 20,000 record. You might be interested in checking it.
Seismosoft Support

[Kirkaguel]

Thanks Seismosoft support for the clarifications. Will try the ESM database for sure.

Hoping as well that automatic RotD100 scaling can be implemented soon.

[rbsce.ph]

Hi Seismosoft,

Do you know how I can apply in Seismostruct the concept of using the Conditional Mean Spectrum for the time history ground motion.
Your response will be highly appreciated.

Thank you.

[seismosoft]

SeismoStruct uses the standard Uniform Hazard Spectrum (UHS) format, unfortunately as proposed by most Standards; Conditional Spectra cannot be introduced directly.
SeismoSoft Support

[huffte]

You should be able to manually generate your CMS, save to a text file, and define the target from the file, rather than auto-generating a response spectrum.

[sama]

Hello all dears,
I have qustion about the method of scalling and amplifying ground motion
as dear "Kirkaguel " said, In ASCE7-22 for scaling Ground motions in {Amplitude Scaling method} (chpter16 at 16.2.3.2 ) maximum-direction spectrum shall be constructed from the two horizontal ground motion components.
For constructing maximum direction spectrum, we can select RotD100, in the ESM database.

-In RotD100 Method After processing and giving us the Scale factor, what should we do? just amplify both direction's components by that scale factor?
-how can we find what angles were used for constructing maximum spectral acceleration for each direction component?
- after finding the angles used for each direction component, how can we rotate the H1 and H2 components?
At last, what do you prefer to do for selecting and scaling ground motions for doing time history analysis based on ASCE7-22 STANDARD that it said maximum-direction spectrum shall be constructed from the two horizontal ground motion components?

thank you so much

[seismosoft]

Here's a response to your questions:

-In RotD100 Method After processing and giving us the Scale factor, what should we do? just amplify both direction's components by that scale factor?
Yes.

-how can we find what angles were used for constructing maximum spectral acceleration for each direction component?
The angle is not given by the databases, hence it cannot be exported by SeismoSelect

-At last, what do you prefer to do for selecting and scaling ground motions for doing time history analysis based on ASCE7-22 STANDARD that it said maximum-direction spectrum shall be constructed from the two horizontal ground motion components?
We cannot comment on this. It is something that should be decided by the engineer, based on the requirements of each project.

Seismosoft Support

[sama]

Thanks, Seismosoft support for the clarifications
I ask to be sure that after scaling is done by seismoselect (use ESM database and select RotD100 Method) then we get the Scale factor,
we just need to amplify both direction's components by that scale factor and there is no need for rotating them?
and then we can use that amplified ground motions in our analysis?

[seismosoft]

SeismoSelect provides the scaling factor to multiply the X+Y ground motions, so that to have the best fit to the provided target spectrum. After that, it is up to the user to decide what to do with this information, and we cannot provide suggestions. What we do is that we usually employ these scaled time histories as they are in the structural analysis
Seismosoft Support