Seismic Behavior Evaluation of Buckling-Restrained Braced Reinforced Concrete Intermediate Moment Frames

Choosing the appropriate seismic resisting system is a necessity in the design of buildings in seismic-prone areas. Seismic design-related requirements are controlled by considering parameters such as displacement amplification, over-strength, and response factors. Due to the lack of these coefficients for a dual system of buckling-restrained braced intermediate reinforced concrete (RC) moment frame in the Iranian seismic code (2800 standard), the aim of this research is to investigate the seismic performance and calculate the mentioned parameters of 4, 10, and 15-story RC structures with the same bay length and with a mentioned dual system and to compare them with the intermediate RC moment frame system. Nonlinear modeling of the structures is done in OpenSees software. Results of the pushover analysis show an increase in the capacity of 4, 10, and 15-story structures with a double system by 10, 5, and 11%, respectively, compared to structures with a moment frame system. Results of the time history analysis indicate the reduction of average maximum and residual drift of the structures with the double system by 37 and 27%, respectively, compared to the structures with the moment frame system. The results of the incremental dynamic analysis also showed that the average acceleration bearing of the structures with the double system is 35% more than the structures with the moment frame system. Also, by examining the fragility curves for collapse damage state, it is clear that this type of bracing reduces the probability of failure of the structures. The obtained seismic parameters for the structures indicate that the ductility, over-strength, and response factors of the structures with the double system are 7, 25 and 36% respectively more than the structures with the moment frame system, and on average the response factor of 5 has been suggested for the buckling-restrained braced intermediate RC moment frames.