A COMPARATIVE STUDY OF THE SEISMIC PROVISIONS OF IRANIAN SEISMIC CODE (STANDARD NO. 2800) AND INTERNATIONAL BUILDING CODE 2003

This article provides a comparison process on how to calculate seismic forces by the static analysis method stated both in the international Building Code (IBC) 2003 and in the Iranian Seismic Code (IS 2800-05). The seismic coefficient for the equivalent lateral force is specified by the following factors: fundamental period, importance factor, spectral response acceleration, and building response modification factor. In this article the above-mentioned parameters are obtained through the IBC 2003 and are compared against those covered in the IS 2800-05. Studies and comparison of factors would lead to significant differences in the results obtained using the two codes. In order to clarify the problem, design base shear of a building with combined system (special moment steel frames + eccentric bracings) in four different soil types and vertical distribution of base shear at story level is obtained, in accordance with both codes; and the results are compared with diagrams and tables. The results prove the need to review the IS 2800-05 and develop more appropriate relations towards achieving economic and functional objectives.