5 Replies Latest reply: Feb 13, 2006 12:00 AM by A.Non

# 4-way logarithmic plot in Mathcad

Is it possible to construct a 4-way logarithmic plot in Mathcad? This type of graph is usually used in presentation of response spectrum in earthquake engineering . I'm studying the characteristics of a response spectra and the best way to present it for visual inspection is to plot it in 4-way logarithmic plot. Does anybody have an experience doing it in Mathcad? How is it done?
• ###### 4-way logarithmic plot in Mathcad
Attached is a sample of 4-way log graph and the corresponding example of what I would like to do. I hope this helps.
• ###### 4-way logarithmic plot in Mathcad

Earthquakes aren't exactly my thing, but is that the standard tripartite plot commonly used in earthquake engineering? If so, a buddy of mine in graduate school figured out how to generate one in Mathcad 2001i, but I don't have the sheet. So, take solace in the fact that it can be done, but I'm afraid that I can't help you more directly than that.

Matt
• ###### 4-way logarithmic plot in Mathcad
I assume you are plotting natural vibration period against pseudo velocity. The deformation and pseudo acceleration are quantities that can be calculated from these. Correct?

If so, generating diagonal lines that represent those two quantities would not be that hard. Numbering the axes is much harder, but fortunately 90% of what you would need is available in the electronic book "Creating Amazing Images With Mathcad" by Byrge Birkeland, section 1.6 (you can download this from the Mathsoft website).

Richard
• ###### 4-way logarithmic plot in Mathcad
Man, I thought I had seen some confusing graphs. . . .

Can we assume that the two sets of orthogonal axes parameters are related? (If we plot a point on the horizontal/vertical coordinates, it is the same point on the diagonal coordinates.) IF so, then the diagonal axes can be defined as functions of the vertical/horizontal axes. At that point, you can probably trick Mathcad into drawing this graph.

Fred Kohlhepp
fkohlhepp@sikorsky.com