verification Incremental dynamic analysis for multiple motions

Contents

Reference

Deng, P., Pei, S., van de Lindt, J. W., Liu, H., & Zhang, C. (2017). An approach to quantify the influence of ground motion uncertainty on elastoplastic system acceleration in incremental dynamic analysis. Advances in Structural Engineering, 20(11), 1744-1756.

Description

Figure 4(a) of the above reference contains the IDA curves of an elastoplastic SDOF system under the Consortium of Universities for Research in Earthquake Engineering (CUREE) GM suite (Krawinkler et al., 2001), which were constructed using the maximum acceleration. In this example, an arbitrary suite of strong ground motions is selected and the maximum acceleration IDA curves are constructed similar to Figure 4(a) of the above reference. The IDA curves of this example strongly resemble those of that figure.

Earthquake motions

Load data from a suite of earthquakes

GM={'Cape Mendocino.dat';
    'ChiChi.dat';
    'Christchurch2011HVPS_UP.dat';
    'Imperial Valley.dat';
    'Imperial_Valley_El_Centro_9_EW.dat';
    'Kobe.dat';
    'Kocaeli.dat';
    'San Fernando.dat';
    'Spitak.dat'};
n=size(GM,1);
dt=cell(n,1);
xgtt=cell(n,1);
for i=1:n
    fid=fopen(GM{i},'r');
    text=textscan(fid,'%f %f');
    fclose(fid);
    t=text{1,1};
    dt{i}=t(2)-t(1);
    xgtt{i}=text{1,2};
end

Setup parameters for IDA analysis

Switch

sw='ida';

Eigenperiod

T=1;

Scaling factors

lambdaF=logspace(log10(0.001),log10(10),100);

Type of IDA analysis

IM_DM='pgv_acc';

Mass

m=1;

Yield displacement

uy = 0.18*9.81/(2*pi/T)^2;

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;

Construct and plot the IDA curves in a loop

Initialize figure

figure()
hold on
% Plot the red bold curve of Figure 4(a) of the above reference
plot([0,0.22,0.34],[0,0.125,2],'r','LineWidth',2)
for i=1:n
    % Apply OpenSeismoMatlab to calculate the ith IDA curve
    S1=OpenSeismoMatlab(dt{i},xgtt{i},sw,T,lambdaF,IM_DM,m,uy,pysf,ksi,AlgID,...
        u0,ut0,rinf,maxtol,jmax,dak);
    % Plot the ith IDA curve
    plot(S1.DM/9.81,S1.IM)
end
% Finalize figure
grid on
xlabel('Maximum Acceleration (g)')
ylabel('PGV (m/s)')
xlim([0,0.5])
ylim([0,2])
drawnow;
pause(0.1)

Copyright

Copyright (c) 2018-2023 by George Papazafeiropoulos

Published with MATLAB® R2022b