Seismic Isolation of an Existing Reinforced Concrete Frame Building in Croatia: Post-Earthquake Rehabilitation Feasibility, Cost Evaluation, and Comparison with Conventional Retrofit

Croatia is located in a seismically active area where moderate to strong earthquakes occur regularly. In addition, the building stock is relatively old and not maintained, so the seismic risk is high. This is evidenced by the damage caused by the earthquakes in Zagreb and Petrinja in 2020. Currently, the reconstruction of earthquake-damaged buildings is mainly carried out using standard structural strengthening methods. However, the application of base isolation has significant potential and could be an effective solution for a specific type of building. In Croatia, base isolation has not yet been used to increase the seismic safety of buildings. This paper investigates the possibility of applying base isolation system to the existing reinforced concrete frame building from the 1930s. In the paper, the building retrofitting solution with base isolation is compared with the conventional strengthening solution that has already been implemented. The application of base isolation in existing buildings was described and non-linear analyses were carried out. Based on the results, the seismic performance of the building under by two solutions are compared, and the construction costs were also analyzed and compared. The results show the potential of base isolation as an effective solution for the reconstruction of existing critical infrastructure buildings.