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Abstrait:
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A site investigation as well as a Seismic Hazard Analysis (SHA) has been carried out for an important building in centre of Tehran (capital of Iran). The aim has been estimating the level of seismic hazard for the site, developing the Uniform Hazard Spectra (UHS) for horizontal as well as vertical component to design against seismic ground motion more precisely and comparison among the UHS and Iranian Seismic Code design spectrum (Standard No. 2800-05, 3rd Edition). At first, it was tried to recognize all the active faults (sources) around the site. Secondly, by using the appropriate attenuation laws, the PGA values on the site were estimated. Maximum values of PGA obtained for the site were 0.932g, 0.626g, 0.497g and 0.358g respectively for 2%, 10%, 20% and 50% probability of exceedence in 50 years ground motions depending on the applied attenuation laws such as Boore-joyner-Fummal, Ambraseys, Ambraseys-Bommer, Ambraseys-Simpson, and Zare-Ashtiany. The UHS, which are more reliable for design purposes, were constructed for the 2%, 10%, 20% and 50% probability of exceedence in 50 years ground motions by using Zare- Ashtiany and Ambraseys-Simpson spectral attenuation laws. Then the design spectrum for Life Safety Level was drawn based on the PGA values and Iranian Seismic Code. Finally, these spectra were compared with each other and the results discussed.
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