Application of the empirical mode decomposition-Hilbert spectrum method toidentify near-fault ground-motion characteristics and structural responses

In this article, the empirical mode decomposition method combined with the Hilbert spectrum method (EMD + HHT) is used to analyze the free-field groun d motion and to estimate the global structural property of building and bri dge structure through the measurement of seismic response data. The EMD + H HT method provides a powerful tool for signal processing to identify nonlin ear and nonstationary data. Based on the decomposed ground-motion signal, t he absolute input energy of each decomposed wave was studied (the fling ste p [pulselike wave] can be separated from the recorded near-fault ground mot ion). Through application of the EMD + HHT method to building and bridge se ismic response data, the time-varying system natural frequency and damping ratio can also be estimated. Damage identification from seismic response da ta of buildings and bridges, particularly from the Chi-Chi earthquake data, is also described.