Synthesis of spectrum-matched bi-directional ground motion with designated elliptical component of polarization

Abstract

The spectrum-matched uni-directional accelograms are generally used to assess the seismic performance of regular bridge structures. However, since actual earthquakes are of bi-directional nature in horizontal components, performance assessment with spectrum-matched bi-directional accelerograms is regarded as advantageous. In this study, a procedure to synthesize spectrum-matched bi-directional acceleroograms from a spectrum-matched uni-directional accelerogram and its Hilbert transform by specifying the ellipitical component of poralization is proposed. Moreover, in order to examine the nature of the synthesized acclerograms, the response of bi-directional nonlinear elasto-plastic dynamic model with a single mass is investigated. As the result, it is found out that the influence of the ellipitical component of poralization on the nonlinear response can be computed with the proposed accelerograms.