Mohammad Asgari - Student of M.S earthquake Pardisan university . Member of Islamic Azad University Elite Group
HassanAli Kazemi - Student of M.S Structure Islamic Azad university of Amol
Masoud Gholizadeh - M.S of structural engineering. Science & research University
Shariyar Asheghian - grauted B.S of civil engineering

In this paper, overstrength, ductility and response modification factor of buckling restrained braced frames (BRBF) dual system were evaluated. To do so, building with various stories anddifferent bracing configuration including diagonal, X, chevron (V and inverted V) bracing were considered. Static pushover analysis, nonlinear incremental dynamic analysis and linear dynamicanalysis have been performed using SAP2000 software. The effects of some parameters influencing response modification factor, including the height of the building and the type of bracing system, were investigated. In this paper seismic response modification factor for each of BRBF dual systems has been determined separately and tentative value of 10.4 has been suggested for allowable stress design method.

ductility, R factor, buckling resistant brace, nonlinear dynamic analysis, pushover analysis