Determination of Uniform Hazard Spectra With Respect to the Near Field Effects for Tehran Region

Document Type : Research Article



Uniform hazard spectrum is a modern and effective method in achieving the design spectra that provide a uniform desirable safety level in performance of structures with different periods. In this study uniform hazard spectrum is determined for Tehran region considering the area and line  seismic sources in the design area using the probabilistic analysis of seismic hazard and spectral attenuation relations. As the ground motions in nearby fault regions cause large damage, in this research the effects of site closeness to the seismic sources is taken into account considering near source spectral attenuation relations besides the far field attenuation ones.                                                                               
The results gained by this method are presented in the form of uniform hazard spectrum, peak ground acceleration and spectral acceleration maps in different periods. Uniform hazard spectrum is obtained by applying approximate method using average values of spectral acceleration in two or three controlling periods and it is compared to the spectra suggested by UBC97 and Iranian 2800-84 codes.  


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