verification Incremental dynamic analysis for ductility response

Contents

Reference

Vamvatsikos, D., & Cornell, C. A. (2002). Incremental dynamic analysis. Earthquake engineering & structural dynamics, 31(3), 491-514.

Description

The ductility response IDA curve of an elastoplastic SDOF system excited by the Loma Prieta, 1989, Halls Valley earthquake (component 090) is constructed at multiple levels of shaking, and compared to the curve shown in Figure 4(a) of the above reference. The SDOF system has T=1 sec and critical damping ratio 5%

Earthquake motion

Load earthquake data

GM='LomaPrietaHallsValley90.dat';
fid=fopen(GM,'r');
text=textscan(fid,'%f %f');
fclose(fid);
t=text{1,1};
dt=t(2)-t(1);
xgtt=text{1,2};

Perform IDA analysis

Switch

sw='ida';

Eigenperiod

T=1;

Scaling factors

lambdaF=logspace(log10(0.01),log10(30),100);

Type of IDA analysis

IM_DM='Sa_mu';

Mass

m=1;

Yield displacement

uy=0.25;

Post yield stiffness factor

pysf=0.01;

Fraction of critical viscous damping

ksi=0.05;

Algorithm to be used for the time integration

AlgID='U0-V0-Opt';

Set initial displacement

u0=0;

Set initial velocity

ut0=0;

Minimum absolute value of the eigenvalues of the amplification matrix

rinf=1;

Maximum tolerance for convergence

maxtol=0.01;

Maximum number of iterations per increment

jmax=200;

Infinitesimal variation of acceleration

dak=eps;

Apply OpenSeismoMatlab

S1=OpenSeismoMatlab(dt,xgtt,sw,T,lambdaF,IM_DM,m,uy,pysf,ksi,AlgID,...
    u0,ut0,rinf,maxtol,jmax,dak);

Plot the IDA curve

Initialize figure

figure()
% Plot the IDA curve
plot(S1.DM,S1.IM/9.81,'k','LineWidth',1)
% Finalize figure
grid on
xlabel('Ductility, \mu')
ylabel('Spectral acceleration Sa(T1,5%) (g)')
xlim([0,3])
ylim([0,3.5])
drawnow;
pause(0.1)

Copyright

Copyright (c) 2018-2023 by George Papazafeiropoulos

Published with MATLAB® R2022b