Determination the Response Modification Factors of Buckling Restrained Braced Frames

Response modification 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 loads. The present paper tries to evaluate the response modification factors of buckling restrained braced frames (BRBFs) utilized for rehabilitation of steel frames. Since, the response modification factor depends on ductility and overstrength, the static nonlinear analysis has been performed on building models including single and double bracing bays, multi-floors and different brace configurations (chevron V, invert V). The BRBFs values for factors such as ductility, overstrength, force reduction due to ductility and response modification have been assessed for all the buildings. The results showed that the response modification factors for BRBFs have high values. It was found that the number of bracing bays and height of buildings have had greater effect on the response modification factors.