Seismic evaluation of reinforced concrete moment frames retrofitted with steel braces using IDA and Pushover methods in the near-fault field

History of the earthquakes occurred in Iran indicates that almost every 10 years, a destructive earthquake inflicts damages to the buildings leading to broad life and financial losses. Indeed, seismic retrofit is the process of retrospectively adding elements into the existing buildings in seismically active areas in order to enhance their resistance to the shakings during earthquake events. In doing so, one of the efficient methods is to utilize steel bracing system. To better understand the seismic performance of such systems, in this paper, RC frames retrofitted by CBF and EBF systems were subjected to 7 near-field earthquakes with varying intensities. To this end, two 10-story frames were first designed in compliance with code-based provisions and then, an IDA was conducted on them. The braces are placed in the first and fifth bays of the frame. Based on the results, retrofit of the RC frames by means of concentric and eccentric braces manages to enhance the yield capacity of the frame by 2.3 and 2times, respectively. Moreover, it was found that application of eccentric braces in RC frames, is capable of reducing the base shear by 7times, compared to the frame benefitting from concentric braces. Concerning the impact of this retrofit system on displacement demands, it was observed that when eccentric braces are employed, the roof drifts are less than those of the CBF. Lastly, it was concluded that more flexible behavior of EBF against earthquake records, increases safety and performance level of the structure in Life Safety performance level.