A CRITERION FOR CONSIDERING SOIL-STRUCTURE INTERACTION EFFECTS IN SEISMIC DESIGN OF DUCTILE RC-MRFs ACCORDING TO IRANIAN CODES

摘要

During the last quarter of the 20th century, the importance of dynamic soil-structure interaction for several structures founded on soft soils was well recognized. If not accounted for in analysis, the accuracy in assessing structural safety in the face of earthquakes cannot be accounted for adequately. For this reason, seismic soil-structure interaction analysis has become a major topic in earthquake engineering. As the Iranian Code of Practice for Seismic Resistant Design of Buildings (Standard No. 2800-05) does not address the soil-structure interaction explicitly, the effects of such interaction on behavior of reinforced concrete buildings with ductile moment-resisting frames, loaded and designed according to the Iranian Building Codes, are studied in this research, using direct soil-structure interaction method. To achieve this objective, four types of structures consisting of 3, 5, 7 and 10 story buildings, which represent the typical buildings in a high risk earthquake prone zone, have been selected in conjunction with three types of soil, representing types II, III and IV, as classified in the Iranian Standard No. 2800-05. Ductile Reinforced Concrete Moment-Resisting Frames, as fixed-base structures, once without soil interaction and the next time considering their soil interaction by direct method are modeled and subjected to different earthquake records. The results of the two cases subjected each to different earthquake records are studied and compared. This Comparison led to a criterion indicate that consideration of soil-structure interaction for seismic design, in buildings higher than three stories on soil type IV (Vs<175 m/s) as well as buildings higher than seven stories on soil type III (175