The effect of energy concentration of earthquake ground motions on the nonlinear response of RC structures

Usually different nonlinear time responses due to earthquake ground motion are distinguished by non-localized spectra, such as the response or power spectra. However, these spectra are often not able to explain the large discrepancy among structural responses caused by different earthquake records. The local spectrum, obtained by the wavelet transform, shows the energy distribution in the time-frequency domain, and helps to understand the very different structural responses. By changing the energy distribution in time of several earthquake records, the effect of energy concentration on the structural nonlinear response is demonstrated. This paper proposes the use of the characteristic peak ground acceleration, which is the peak of the signal constructed by only a few special wavelet components of an earthquake record, to quantify the difference between earthquake records, since this measure indicates the magnitude of the energy concentrated around the fundamental period of a structure.