A SEMI-EMPIRICAL MODEL FOR SIMULATING DESIGN ACCELEROGRAMS
Liao Zhenpeng , Wei Ying (Institute of Engineering Mechanics, State Seismological Bureau)
A semi-empirical method for simulating design accelerograms in a region is presented for use in aseismic design. The empirical Green's functions is formed statistically in terms of all strong motion records available in the region from ire-quency domain, instead of modifying individual records of smaller earthquakes in that region in time domain.Other important parameters involved in the simulation technique are the total rupture length and the source spectrum, which are derived directly from the strong motion data in that region as well. The simulated accelerograms are of ncnstationary characteristics in time and statistically consistent with the dispersion and attenuation of seismic waves in the realistic earth medium of the region. Since effects of directivity on the accelerograms can be included in the simulation, it is suggested that a set of design accelerograms at an engineering site should be simulated for ditferent azimuths of the site relative to the rupture section of a seismogenic fault because where a future earthquake would take place on the active fault is usually unknown.