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AMaloff (Geotechnical) (OP)
23 Aug 01 14:57
I'm trying to find a software that I can use to plot four-way logarithmic graphs (response spectrum). Right now I'm doing this by hand. In addition I'm trying to find a software to construct smoothed response spectra out of attenuation relationships

This will be used to construct plots for various site-to-source distances values an so on. If someone can provide me any assistance on this matter I will be very gratefull


ludvik (Structural)
23 Aug 01 18:17
do you have a copy of mathcad? i'm not sure whether it does four way log plots, but it has plenty of hardcore math and graphing functions. in fact, i'm not sure what a four way plot is...what is a tripartite graph? does excel not do enough? i though response spectrums where ploted on just a normal 2d logarithmic graph.

Taro (Structural)
23 Aug 01 19:24
A tripartite plot is a logarithmic spectral plot with one vertical and two diagonal axes from which you can read acceleration, velocity, or displacement for a given period.  I don't know of commercial software that specializes in these plots.  In grad school, I used Matlab to construct them.
Qshake (Structural)
23 Aug 01 21:50
Yes, I've used MathCad to construct tripartite graphs as well.  My references at the time were Geotechnical Earthquake Engineering by Steven Kramer and Structural Dynamics by Mario Paz.
ishvaaag (Structural)
24 Aug 01 13:08
I thought I had posted an entry to thes question, seems lost, so I repeat... I have EQPACK by CASE Computer Aided Structural Engineering that makes RS plots..., and is part of a large set of programs to EQ related, so if not this may be other may serve to you. The one I have is DOS based.

Also, Qshake, have you posted anywhere such Matchcad sheet available? Could you if not? I have Mathcad 2000 Pro and would love to see it...graduating the diagonal logarithms must be cumbersome, no?
Helpful Member!  JAE (Structural)
24 Sep 01 19:09
There is also a program called SHAKE and many others that does a lot of this.  Try this website:

JAE (Structural)
24 Sep 01 19:14

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