verification Constant strength response spectrum

Contents

Reference

Tena-Colunga, A. (1999). Simplified seismic evaluation of existing structures, 8th Canadian Conference on Earthquake Engineering, Vancouver, Canada, 317-322.

Description

In the above reference, a new type of spectrum is proposed, the constant strength response spectrum (CSRS). A displacement ductility demand spectrum (DDDS) relates peak displacement ductility demands (and other important response quantities, i.e., displacements) with structural periods of nonlinear elastic-perfectly-plastic hysteretic SDOF systems with given yield strengths. Figure 1 of the above reference is verified in this example. The SDOF system has a yield strength ratio equal to V/W=0.15 and the acceleration time history of the SCT-EW component recorded during the 1985 Michoacan earthquake is considered.

Load earthquake data

Earthquake acceleration time history of the 1985 Michoacan earthquake will be used (SCT-EW component). The txt file contains the following columns: time, acceleration N-S, acceleration E-W, acceleration V

fid=fopen('sct190985.txt','r');
text=textscan(fid,'%f %f %f %f');
fclose(fid);
t=text{1,1};
dt=t(2)-t(1);
xgtt=9.81*text{1,3};

Calculate constant strength response spectra of earthquake motion

Switch

sw='csrs';

Eigenperiods

T=linspace(0.1,5,50);

Critical damping ratio

ksi=0.05;

Strength ratios

fyR=0.15;

Post-yield stiffness factor

pysf=0.001;

Apply OpenSeismoMatlab

S1=OpenSeismoMatlab(dt,xgtt,sw,T,ksi,fyR,pysf);

Plot the ductility demand response spectra

Initialize figure

figure()
% Plot the constant strength ductility demand response spectra
plot(S1.Period,S1.CSSmu, 'k-', 'LineWidth', 1)
% Finalize figure
grid on
xlabel('T (sec)')
ylabel('\mu (-)')
xlim([0,5])
ylim([0,10])
drawnow;
pause(0.1)

Plot the displacement demand response spectra

Initialize figure

figure()
% Plot the constant strength displacement demand response spectra
plot(S1.Period,100*S1.CSSd, 'k-', 'LineWidth', 1)
% Finalize figure
grid on
xlabel('T (sec)')
ylabel('\Delta (cm)')
xlim([0,5])
ylim([0,100])
drawnow;
pause(0.1)

Copyright

Copyright (c) 2018-2023 by George Papazafeiropoulos