HAZARD-CONSISTENT GROUND MOTIONS: GENERATION ON THE BASIS OF UNIFORM HAZARD FOURIER SPECTRA

Abstract

Design seismic forces depend on peak ground acceleration (PGA) values and on the shape of response spectra (RS) dictated by building codes or that need to be evaluated on a site-specific basis. The PGA values and RS strictly depend on earthquake magnitude and distance, style of faulting and in cases, near-source effects (e.g., rupture directivity), as well as on the regional and local geological conditions. At present, there is no doubt that it is necessary to construct so-called site-and region-specific building code provisions reflecting the influence of different magnitude events at different distances that may occur during the lifetime of the construction, as well as the variety of local ground conditions. A scheme of Uniform Hazard Response Spectra and PGA estimation considering local site response is described in this article. The assessments of these design parameters are obtained on the basis of Uniform Hazard Fourier spectra using the concept of "dominant earthquakes". The effect of local geology is included by means of the soil/reference site spectral ratios. The results of using the method are presented for the regions characterized by dif-ferent seismicity and tectonics and compared with the data obtained during the recent strong earthquakes: the Caucasus (Armenia, the 1988 Spitak earthquake region) and the Turan Plate (Central Asia, the 1979 and 1984 Gazli earthquakes region).