Simplification Of Earthquake Accelerograms For
Quick Nonlinear Time History Analyses By Using
Modified Inverse Fourier Transform
Author(s)
A. Faroughi & M. Hosseini
Abstract
In seismic design and evaluation of irregular buildings most codes recommend
nonlinear time history analysis (NLTHA), which is very time-consuming, mainly
since the time step size of the digitized accelerograms is usually very small.
Therefore, if the NLTHA analysis can be performed by large time steps without
losing much precision, it can be very helpful. This paper introduces a method
for simplification of accelerograms based on the modification of their Fourier
analyses. In the proposed method the Fourier Spectrum of the accelerogram is
calculated first, and then, by using a computer program, developed by the
authors, the corresponding Inverse Fourier Transform is calculated using a
relatively large time step, depending on the structure’s periods, which is usually
5 to 10 times of the original accelerogram’s time step) to create the simplified
accelerogram. Obviously, time history analysis by using this simplified
accelerogram is much less time-consuming. Numerical results show that the
maximum response values obtained by using the simplified accelerograms have
only 5 to 10 percent error, depending on the type of the structure and the features
of the used records.
Keywords: Fourier and Inverse Fourier Transforms, time step size.
Keywords
Fourier and Inverse Fourier Transforms, time step size
Related Book
Other papers in this volume
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