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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 one important hospital in Iran. The aim has been estimating the level of seismic hazard for the site and developing the Uniform Hazard Spectra (UHS) for horizontal component to verify the performed seismic design of the building and preparing seismic rehabilitation process. At first, it was tried to recognize all the active faults around the sites. Secondly, by using the appropriate attenuation relationships and two methods for calculating seismicity parameter, direct and Kijko methods, the horizontal PGA values on the sites were estimated. These values obtained vary between 0.350g and 0.995g for 2%, 0.251g and 0.661g for 10%, 0.212g and 0.533g for 20% and 0.169g/0.381g for 50% probability of exceedence in 50 years ground motions depending on the applied attenuation laws such as Ambraseys, Ambraseys and Bommer and Zare and Ashtiany. The more exact horizontal PGA values, obtained from mean of two mentioned methods (direct and Kijko methods), for 2%, 10%, 20% and 50% probability of exceedence in 50 years ground motions were 0.614g, 0.412g, 0.337g and 0.256g. Finally, 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. The 10% and 2% spectra (first and second hazard level) compared with Iranian Standard Design Spectrum (SDS) and 1.5 times of this spectrum respectively. This comparison showed that the values of UHS for short and medium periods are more and for long periods are less than values of Iranian Standard Design Spectra.
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