A STUDY ON THE DURATION OF STRONG （研究期间强劲）.pdf

Bulletin of the Seismological Society of America. Vol. 65, No. 3, pp. 581-626. June 1975 A STUDY ON THE DURATION OF STRONG EARTHQUAKE GROUND MOTION BY MI D. TRIFUNACAND A. G. BRADY A simple definition of the duration of strong earthquake ground motion based on the mean-square integral of motion has been presented. It is closely related to that part of the strong motion which contributes significantly to the seismic energy as recorded at a point and to the related spectral amplitudes. Correlations have been established between the duration of strong-motion acceleration, velocity, and displacement and Modified Mercalli intensity, earthquake magnitude, the type of recording site geology, and epicentral distance. Simple relations have been presented that predict the average trend of the duration and other related param- eters as a function of Modified Mercalli intensity, earthquake magnitude, site geology and epicentral distance. INTRODUCTION The duration of strong earthquake ground motion is one of the main parameters characterizing this natural phenomenon. Yet very little has been done, so far, to describe it quantitatively in terms of earthquake magnitude, source-to-station distance and the effects of geological environment. Remembering the significance of the duration of excita- tion on the response of nonlinear yielding structures and that it determines the number of cycles during vibration, it becomes evident that, together with the overall amplitudes of induced response, the duration must play a major role in governing the outcome of any response to strong ear