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# Plotting Response Spectrum

## Plotting Response Spectrum

(OP)
Hi Folks,

I am quite new to earthquake engineering and was hoping someone could help me out.

I am looking at the El Centro 1940 quake and trying to plot the earthquakes response spectrum. I am using excel.

At this stage, I have plotted Acceleration v Time, Velocity v Time and Displacement v Time. I have derived values for velocity and displacement using acceleration for both X and Y directions.

I would like to know, if some can help me, how do I plot the response spectrum for Spectral Acceleration v Period, Sa v T. My base Sa = 0.32g (x direction) and 0.096g (y direction). Also I have been trying to use Sa = a(t) + ag(t) to solve this problem but not getting anywhere. This may be very simple but I am unsure how to go about this.

Cheers M

### RE: Plotting Response Spectrum

Are you trying to make response spectrum from raw data of El Centro Earthquake (acceleration versus time?

(OP)
Yes exactly.

### RE: Plotting Response Spectrum

you should have knowledge about to calculate the SDOF response under certain forces (in this case is el centro acceleration).
this related to integration of partial integration. please see attachment.

after you get the response of SDOF, the you can choose the maximum response (can be displacement, acceleration, velocity), most often is displacement.
and then do it the same thing, for some of period natural, for ex: for Tn= 0.1, sec, 0.5 sec and so on.
Then the plot you did is called response spectra.

### RE: Plotting Response Spectrum

(OP)
Thanks for the document. I will have a more detailed look at it.

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