An efficient algorithm for identifying pulse-like ground motions based on significant velocity half-cycles

Ground motions with strong velocity pulses are of particular interest to structural earthquake engineers because they have the potential to impose extreme seismic demands on structures. Accurate classification of records is essential in several earthquake engineering fields where pulse-like ground motions should be distinguished from nonpulse-like records, such as probabilistic seismic hazard analysis and seismic risk assessment of structures. This study proposes an effective method to identify pulse-like ground motions having single, multiple, or irregular pulses. To effectively characterize the intrinsic pulse-like features, the concept of an energy-based significant velocity half-cycle, which is visually identifiable, is first presented. Ground motions are classified into 6 categories according to the number of significant half-cycles in the velocity time series. The pulse energy ratio is used as an indicator for quantitative identification, and then the energy threshold values for each type of ground motions are determined. Comprehensive comparisons of the proposed approach with 4 benchmark identification methods are conducted, and the results indicate that the methodology presented in this study can more accurately and efficiently distinguish pulse-like and nonpulse-like ground motions. Also presented are some insights into the reasons why many pulse-like ground motions are not detected successfully by each of the benchmark methods.