Assessment of Multi-Criteria Evaluation Procedures for Identification of Optimal Seismic Retrofitting Strategies for Existing RC Buildings

The improvement of the seismic performance of existing buildings is majorly accomplished by adopting one or more retrofitting interventions. The selection of the latter is generally made considering conventional parameters, based on e.g. economic or structural considerations, without carrying out a comprehensive and integrated comparison of different retrofitting solutions. Instead, for an optimal choice of a retrofitting option, it is necessary to include different evaluation criteria to better assess the effectiveness of each strategy. This aspect becomes even more relevant when referring to buildings of strategic importance, such as school buildings, for which typical structural response-oriented criteria may not be enough to identify the best choice. This paper implements and scrutinizes various multi-criteria evaluation methodologies to comparatively assess retrofitting options for an existing reinforced concrete (RC) school building, considering different aspects, weighted according to their deemed importance. These evaluation criteria focus not only on the structural performance but also on how each intervention affects the operability of the building and on economic aspects. A comparative performance assessment is conducted on a detailed numerical model, able to reproduce the main structural deficiencies observed during past earthquakes in RC school buildings. Then, different retrofitting interventions are identified with the aim to solve the structural issues and improve the overall performance of the case-study school building. The seismic performance is quantified in terms of seismic losses, including the contribution of non-structural elements, amongst several other metrics. Finally, the outcomes of the different evaluation methodologies, which denote a non-unanimous optimal solution, are compared and critically analyzed.