verification Fourier amplitude spectrum of OpenSeismoMatlab

Contents

Reference

Analyses of strong motion earthquake accelerograms, Volume IV - Fourier Amplitude Spectra, Part H - Accelerograms IIH115 through IIH126, California Institute of Technology, Earthquake Engineering Research Laboratory, Report No. EERl 74-100, 1974.

Description

Verify the Fourier amplitude spectrum at page 14 of the above reference for the San Fernando earthquake, Feb 9, 1971, 0600 PST, IVH115 71.024.0 15250 Ventura BLVD., basement, Los Angeles, Cal. Component N79W.

Earthquake motion

Load earthquake data

eqmotions={'SanFernando1971VenturaBlvdBasement15250LosAngelesCalN79W'};
data=load([eqmotions{1},'.dat']);
t=data(:,1);
dt=t(2)-t(1);
xgtt=100*data(:,2);

Calculate the Fourier amplitude spectrum

Switch

sw='fas';

Apply OpenSeismoMatlab

S1=OpenSeismoMatlab(dt,xgtt,sw);

Plot the Fourier amplitude spectrum

Initialize figure

figure()
% Plot the Fourier amplitude spectrum on page 14 of the above reference
plot(S1.freq,S1.FAS,'k','LineWidth',1)
% Finalize figure
grid on
xlabel('Frequency - CPS')
ylabel('Fourier amplitude spectrum - cm/sec')
ylim([0,200])
xlim([0,25])
drawnow;
pause(0.1)

Plot the Fourier amplitude spectrum in logarithmic scale

Initialize figure

figure()
% Plot the Fourier amplitude spectrum on page 15 of the above reference
plot(log10(S1.freq),log10(S1.FAS),'k','LineWidth',1)
% Finalize figure
grid on
xlabel('Log of frequency - CPS')
ylabel('Log of Fourier amplitude spectrum - cm/sec')
ylim([-2,3])
xlim([-2,2])
drawnow;
pause(0.1)

Copyright

Copyright (c) 2018-2023 by George Papazafeiropoulos

Published with MATLAB® R2022b