Leila Kalani Sarokolayi - Assistant Professor, Department of Civil Engineering, Tabari university of Babol, Babol, Iran
Sirous Gholampour dehkordi - Assistant Professor, Department of Civil Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran
Masoud Shafaghati sefidab - MSC Student, Department of Civil Engineering, Tabari university of Babol, Babol, Iran

Response modification factor (R-factor) is one of the seismic design parameters to consider nonlinear performance of building structures during strong earthquake. Relying on this, many seismic design codes led to reduce earthquake loads imposed to the structure. The present paper tries to evaluate the R-factors of conventional concentric braced frames (CBFs) and special moment frames (MRFs) in duplex steel buildings with level difference in their floors. Since, the R-factor depends on ductility and over strength, the incremental nonlinear static analysis, push over analysis, has been performed on 4, 7 and 10 storey building models with three floor level differences and including CBFs and special MRFs systems in x and y directions of buildings respectively. The results showed that the R-factors for CBFs system in duplex buildings were higher than ones in conventional buildings without floor level differences while for MRFs system it was found that on 4 and 7 storey duplex buildings, the R-factors were decreased and with the increase in building height to 10 storey, they were increased compared to conventional models.

Response Modification Factor, Duplex Building, Push-over Analysis, Special Moment Frames, Concentrically Braced Steel Frames