example Comparison of elastic and constant ductility response spectra for mu=1

Compare the linear elastic acceleration response spectrum and the constant ductility response spectrum for mu=1 (degenerates to linear elastic). Also, compare with corresponding results of SeismoSignal software

Contents

Input

Earthquake motion

eqmotions={'Imperial Valley'}; % Imperial valley 1979
data=load([eqmotions{1},'.dat']);
t=data(:,1);
dt=t(2)-t(1);
xgtt=data(:,2);

Set the eigenperiod range for which the response spectra will be calculated.

Tspectra=(0.05:0.05:4)';

Set critical damping ratio of the response spectra to be calculated.

ksi=0.05;

First we use the CDS to calculate linear response

Set the target ductility

mu=1; % mu=1 equivalent to a linear SDoF

Extract constant ductility response spectra

sw='cdrs';

Calculation CDRS{i}=[S.Period,S.CDSd,S.CDSv,S.CDPSa,S.fyK,S.muK,S.iterK];

S1=OpenSeismoMatlab(dt,xgtt,sw,Tspectra,ksi,mu);

Next we use ES to calculate linear response

Extract linear elastic response spectra

sw='elrs';

Initialize LERS

LERS=cell(numel(eqmotions),1);

Calculation LERS{i}=[S.Period,S.Sd,S.PSv,S.PSa];

S2=OpenSeismoMatlab(dt,xgtt,sw,Tspectra,ksi);

Results from SeismoSignal

fileID = fopen('SeismoSignal_Imperial Valley.txt');
for idx = 1:5
    fgetl(fileID);
end
C = textscan(fileID,repmat('%f',1,12));
fclose(fileID);

Output

Plot spectral acceleration response spectra

plot(S1.Period,S1.CDSa,'k','LineWidth',1);
hold on
plot(S2.Period,S2.Sa,'r','LineWidth',1);
plot(C{1},C{2})
legend('CDS with mu=1','LinearSpectrum','SeismoSignal');
xlabel('Period');
ylabel('Spectra Acc.')

Copyright

Copyright (c) 2018-2023 by George Papazafeiropoulos

Published with MATLAB® R2022b