ABSTRACT: – Reinforced Concrete buildings without bracing are very popular in present context. Most of the RC building without bracing are weak in drift and deflection criteria. In this research, the seismic performance of reinforced concrete frame retrofitted with different types of steel bracing has been studied using dynamic response spectrum method. Three models which represents moment resisting RC frame of 7, 12 and 18 stories as low, mid-rise and high-rise buildings respectively were selected as a case study and are designed for gravity loads and seismic forces according to Indian standard code with the help of Finite Element Software SAP2000. Efficacy of using different types of steel bracing such as X, V, Inverted V, K, and diagonal as retrofitting measure on those models has been studied. At least 25 percent of the design base shear should be resisted by Moment resisting frame independently. The response of the buildings in terms of base shear, storey drift, storey displacement were studied for both original building as well as retrofitted building. The seismic performance enhancement of buildings using different types of steel bracing has been studied by comparing those responses of the buildings. Results shows that steel bracing can be effectively used as a retrofitting measure in order to increase the structural stiffness and decrease interstorey drift as well as storey displacement of RC frame structure. Among different types of steel bracing X- type and Inverted V bracing showed significant decrease in storey displacement as well as storey drift of the buildings.

Keywords: – Reinforced concrete frame, Steel braces, Retrofitting, Response spectrum, Storey displacement, Storey drift ratio.