Seismic Evaluation of Reinforced Concrete Moment Frames Retrofitted with Steel Braces Using IDA and Pushover Methods in the Near-Fault Field

Abstract

One of the methods for seismic retrofitting in reinforced concrete structures is the application of steel braces. In this paper, the effect of concentric and eccentric bracing systems on the seismic performance of dual reinforced concrete building systems was inspected through seven near-fault earthquake records. Pursuant to that, two reinforced concrete frames with 10-story and 5 spans were designed and analyzed by means of the incremental dynamical analysis (IDA) method where the braces were placed in the 1st and 5th spans. The results revealed that the bearing capacity of the reinforced concrete frame by applying CBF and EBF braces increases up to 2.3 and 2 times, respectively. The use of EBF brace in a reinforced concrete frame reduces the amount of the base shear applied to the structure up to 7 times compared with the CBF frame. Approximately, the displacement of the roof in the EBF frame is less than the CBF frame. Moreover, the ductility of the EBF frame against earthquake records causes an increase in the performance level of structure to the immediate occupancy (IO).