Hazard-consistent ground motions: Generation on the basis of uniform hazard Fourier spectra

Design seismic forces depend on peak ground acceleration (PGA) values and o n the shape of response spectra (RS) dictated by building codes or that nee d 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 region al and local geological conditions. At present, there is no doubt that it i s necessary to construct so-called site- and region-specific building code provisions reflecting the influence of different magnitude events at differ ent distances that may occur during the lifetime of the construction, as we ll as the variety of local ground conditions. A scheme of Uniform Hazard Re sponse Spectra and PGA estimation considering local site response is descri bed in this article. The assessments of these design parameters are obtaine d on the basis of Uniform Hazard Fourier spectra using the concept of "domi nant earthquakes". The effect of local geology is included by means of the soil/reference site spectral ratios. The results of using the method are pr esented for the regions characterized by different 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 Pla te (Central Asia, the 1979 and 1984 Gazli earthquakes region).