Mostafa GHASSEMI - MSc. Graduated in structural engineering, University of Zanajn, Zanajn, Iran
Mahdi GORZIN - MSc. Graduated in structural engineering, University of Zanajn, Zanajn, Iran
Hossein TAJMIR RIAHI - Assistant professor, University of Isfahan, Isfahan, Iran

Response modification factor is one of the seismic design parameters which considers nonlinear performance of structures during strong earthquakes. This parameter is widely used in linear desing of structural members of buildings. Design codes are proposed response modification factors for common structural systems. Comparing on these values of lateral resistant systems gives a general information about their nonlinear behaviour in earthquakes and helps designers to select the best system for the under design structure. The present paper tries to evaluate response modification factors of a new structural lateral resistant system called ‘T-shape resistant frame’ (TRF) and compares its performance with eccentrically braced frames (EBF). in order to comparing the two systems, two dimensional steel frames with 3, 5, 8 and 12 stories and one bay are studied. These frames have been designed with TRF and EBF systems in the same condition to achieve a resonable analogy. The TRF and EBF parameters such as response modification, ductilityandover strength have been evaluated for all the frames. Response modification factors obtained from analysis of TRF frames illustrates that this system have high values. Results show that these factors of TRF are more than EBF ones. TRF’s ductility factor is increased with height so that 8 and 12 stories frames with TRFs are more than the EBF frames. It can be inferred that ductility factor of the TRF frames are significant. Morever, overstrength factors obtained from analyzing the TRF frames are more than the EBF frames in all models. Using TRF system in structures causes an optimum design because of its great response modification factor.

T-shape Resistant Frame, Eccentrically Braced Frame, Response Modification Factor, OverStrength Factor, Ductility Factor