example PulseDecomp

Pulse decomposition of a velocity time history in OpenSeismoMatlab

Generate earthquake motion
Setup parameters for PulseDecomp function
Calculate Pulse and residual motion
Plot the initial, pulse and residual time histories
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Generate earthquake motion

For reproducibility

rng(0)

Generate earthquake velocity time history with a pulse

duration = 10;
dt = 0.01;
t = linspace(0, duration, duration /dt)';
num_sin_components = 3;
xgt = zeros(length(t),1);
for i = 1:num_sin_components
    s = rand * sin(2 * pi * 0.5*rand * t + rand);
    xgt = xgt + s;
end

Setup parameters for PulseDecomp function

Wavelet family to be considered as the contained pulse

wname = 'db4';

Minimum pulse period for the continuous 1-D wavelet transform

TpMin = 0.25;

Minimum pulse period for the continuous 1-D wavelet transform

TpMax = 15;

Number of pulse period values between TpMin and TpMax

nScales = 50;

Calculate Pulse and residual motion

Apply PulseDecomp

[pulseTH,resTH,Tp,wavScale,wavCoef] = ...
    PulseDecomp(dt,xgt,wname,TpMin,TpMax,nScales);

Plot the initial, pulse and residual time histories

Initialize figure

np = length(xgt);
time = dt:dt:dt*np;
fig = figure();
% Initial velocity time history
subplot(3,1,1)
plot(time, xgt, '-k')
legend('Original ground motion','location','northwest')
ylabel('Velocity');
set(gca, 'xticklabel', [])
% Pulse velocity time history
subplot(3,1,2)
plot(time, pulseTH, '-r')
legend('Extracted pulse','location','northwest')
ylabel('Velocity');
set(gca, 'xticklabel', [])
% Residual velocity time history
subplot(3,1,3)
plot(time, resTH , '-k')
legend('Residual ground motion','location','northwest')
hy = ylabel('Velocity');
hx = xlabel('Time [s]');
drawnow;
pause(0.1)

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