Evaluating Retrofitting Strategies of Low-to-Mid-Rise Reinforced Concrete Structure Based on Its Seismic Fragility

In earthquake-prone regions such as Indonesia, this situation has drawn public attention and led to difficulties in implementing certain policies and decision-making. One of the challenging issues in seismic risk reduction is evaluating the efficacy of seismic retrofitting the existing low-to-mid reinforced concrete building. Therefore, this research evaluates the retrofitting of low-to-mid-rise reinforced concrete structures to evaluate the efficacy of the retrofitting strategy rationally using Fiber Reinforced Plastic (FRP), Buckling Restrained Braced Frame (BRBF), and shear wall strategies. Rusunawa at Cilacap, a mid-rise RC apartment for low-income people, was selected as a benchmark building to compare existing and retrofitted seismic fragility. Furthermore, a 3D computer model was developed to predict the seismic response of the structure using a nonlinear static (pushover) analysis. The pushover method produces a capacity curve, showing that the unreinforced structure has a maximum base shear value of 15.2x103 kN. While the reinforcement of low to medium rise reinforced concrete structures using the Fiber Reinforced Plastic strategy has a maximum base shear value of 15.3x103 kN, then reinforcement using the Buckling Restrained Braced Frame strategy with a maximum base shear value of 16.2x103 kN. The shear wall reinforcement has a value maximum base shear of 19.7x103 kN. The capacity curves as the analysis outputs were then converted into the fragility and used to rationalize the probabilistic value of the damage states between existing and retrofitted buildings.