Implementation of an Evaluation Framework for FRP Jacketing–Based Seismic Retrofitting of Substandard RC Buildings on a Regional Scale

Abstract Recent earthquakes in Türkiye have demonstrated the urgent need for practical strategies that can be scalable to the city level to reduce seismic risk in large substandard reinforced concrete (RC) building stocks. As fiber-reinforced polymer (FRP) jacketing is widely used as an effective technique for the enhancing ductility and shear capacity of substandard RC members, its applicability at the regional scale and its performance limits remain insufficiently quantified. This study proposes a rapid, performance-based evaluation and decision framework to identify buildings that can be effectively retrofitted using FRP jacketing, as well as those for which FRP interventions are inherently inadequate due to global strength or drift limitations. The framework integrates the PERA2019 rapid seismic assessment methodology with code-based provisions for FRP retrofitting and is applied to a large data set comprising approximately 25,000 existing RC buildings in Istanbul. A set of explicit selection criteria is introduced to exclude buildings unsuitable for FRP jacketing. For the remaining buildings, an incremental FRP jacketing scheme is employed to determine the minimum number of FRP plies required to achieve the maximum attainable seismic risk reduction. The results demonstrate that even a single layer of FRP jacketing can substantially reduce seismic risk for a significant portion of the building stock, while additional layers provide diminishing returns. Furthermore, the study quantifies the relationships among retrofit effectiveness, seismic demand, building capacity, and retrofit cost, highlighting the practical boundaries of FRP-based interventions. The proposed framework provides engineers and decision makers with a rational tool for large-scale prioritization and implementation of FRP jacketing in seismic risk mitigation campaigns.