Seismic Retrofitting Strategy for Improved Strength and Ductility of a Plan-Wise Irregular Reinforced Concrete Building

A mixed retrofitting intervention including both fibre reinforced polymer (FRP) wrapping and reinforced concrete (RC) jacketing applied to selected columns was proposed and investigated by numerical analyses with the aim of improving the seismic performance of a four-storey plan-wise irregular RC building designed for gravity loads. Retrofitting was aimed at both reducing the torsional component of the seismic response and improving the local and global ductility of the structure. A displacement-based procedure using nonlinear static pushover analyses was adopted to assess the seismic performance of the structure in the original configuration and to select the retrofitting intervention. As a result of the asymmetry of the investigated structure, appropriate correction factors were computed in order to take into account the effects of torsion. Nonlinear dynamic analyses were carried out to verify the effectiveness of the retrofitting intervention strategy. Demand-to-capacity ratio (DCR) values were used to evaluate the damage level of columns and to identify the most critical columns affecting the seismic performance of the structure.