Quantitative Modeling of Pulse-Like Ground Motions Using Imperialist Competitive Optimization Algorithm

Increasing attention in quantitative and qualitative models has been paid to the dominant velocity pulse of the pulse-like ground motions. Manual trial and error approach for fitting of time history and response spectrum of the actual record and simulated pulse has been employed to obtain pulse parameters of these models. In this study, a mathematical model and the imperialist competitive algorithm (ICA) are used to overcome the limitations of the previous studies. For this purpose, an objective function is defined as the norm deviation of the time history and response spectrum of the actual record and simulated pulse. The proposed approach is capable of identifying and extracting the dominant pulse of any pulse-like record, and consists of 91 pulse-like records used in this study. In all of 91 records, the highest accordance with time history and elastic response spectrum of actual records and extracted pulses is achieved. As a case study, the extracted pulses of the 1999 Chi-Chi earthquake are used to generate artificial pulse-like records. The dynamic responses of the 3-story moment frame in SAC project subjected to generated records are investigated. The results show that the proposed approach can be used in parametric studies of pulse-like ground motions.