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Evaluation of intensity measures for ground motion selection to be used in the analysis of highway flyover bridges

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2019
Akray, Ayha
Time history analysis that requires a proper ground motion selection is becoming popular as computational methods advance. It has been known that scaling any ground motion will not be the best fit to be used in the time history analysis. Over the years, scientists have studied recorded ground motion data by the help of a set of intensity measures to characterize the movement. The aim of this study is to compare intensity measures of ground motions with seismic demand parameters used in nonlinear time history analyses of four flyover intersection highway bridges with various natural periods varying between 0.84 s and 1.78 s. In this scope, nonlinear time history analyses have been performed on a total of forty-two ground motion records. Twenty-three intensity measures grouped as acceleration, velocity, displacement based and other categories have been researched to detect a correlation with column base seismic demand parameters consisting of axial, shear and moment forces. Traditionally, the peak ground acceleration has been used as the main measure between seismic hazard and structural analysis. However, the results showed that intensity measures such as Velocity Spectrum Intensity (cm), Sa(T1) (g) and Housner intensity (cm) have better correlations with seismic demand parameters compared to other intensity measures. In general, the velocity-related intensity measures are the most appropriate intensity measures for the highway bridges analyzed.