Methodology for Assessing the Performance of RC Structures with Breakaway Infill Walls under Tsunami Inundation

The increasing attention of governments and insurance companies toward the evaluation of tsunamis' impacts on coastal communities led to a renewed interest in assessing the behavior of existing buildings under onshore tsunami flows. Codes and standards regulating assessment procedures for existing structures under tsunami loading are currently missing, and only a few design codes for vertical evacuation shelters can be found. Furthermore, structural analysis methods currently assume watertight buildings for the assessment of their performance under tsunami inundation. In this work, a methodology for assessing the performance of reinforced concrete (RC) buildings that considers explicitly the progressive failure of exterior breakaway infill walls hit by tsunami flows is proposed. The effects of the progressive failure of breakaway infill walls on the overall performance of RC buildings have been highlighted on case-study buildings representative of low-, mid- and high-rise buildings built before the 1980s in the Mediterranean area, characterized by masonry infill walls with low out-of-plane (OOP) capacity. In the absence of specific guidelines for assessment, load models provided by existing tsunami design codes for evacuation buildings were adopted and opportunely modified for the case of buildings with breakaway infill walls. The explicit consideration of the failure of exterior breakaway infill walls completely changed the distributions of loads inside the structure, leading to different structural capacity and damage evolution with respect to watertight buildings. The height of the building affected the global capacity but did not influence the damage evolution. The proposed methodology can represent a suitable solution for a realistic performance assessment of frame structures with breakaway claddings.