GNGTS 2017 - 36° Convegno Nazionale

450 GNGTS 2017 S essione 2.3 Structural analysis. In such a framework, both linear and non- linear static analyses can be used. However, dynamic analyses will not be carried out, lacking adequate dynamic input definition for the tsunami waves and proper detailed structural knowledge of the response. In particular, linear analyses can be used in a preliminary approach to study stress distributions in buildings under tsunami loads, while non-linear pushover analyses can be used for more accurate results to provide fragility curves. Previous works have proved that force based pushover analysis (changing the wave inundation depth) gives more accurate results than displacement based pushover. Linear static analyses confirmed that stresses arise only in the storeys affected by tsunami waves; therefore, storeys not hit by waves have no significant structural function and can be modelled as overloads in simplified models. Two different approaches can be used to simulate increasing tsunami loads: assuming a fixed inundation depth and increasing the pressure level, or assuming a pressure profile compatible with specific material density but increasing the inundation depth (Petrone et al. , 2017). Additionally, in RC structures, while increasing the inundation depth, the maximum bending moment (hence plastic hinge formation) moves along the column height, and the position of potential plastic hinges rapidly moves to the column ends, hence confirming the feasibility of concentrated plasticity approaches. Information on coastal existing building features. Information about number of storeys of structures, number of concrete and masonry buildings and construction periods, for the analysed areas, can be retrieved from census databases of the National Institute of Statistics (ISTAT) and from furthermore refined databases mainly acquired during post-earthquake surveys of civil protection and other agencies. Construction periods related to historic changes of building codes and seismic maps are important factors for the correct definition of the structural features of the analysed residential buildings. At present, the analysis of the coastal building stock is limited to areas where tsunami inundation is expected. According to a global large-scale approach, a simple attenuation law has been adopted for the inundation depth gradient from the coastline running up the landside. According to Italian National Institute of Geophysics and Volcanology (INGV) studies, a simplified gradient was adopted, for which every meter of wave height along the coast corresponds to 200 meters of inland inundation distance, in a hypothetical horizontal surface condition and without considering any obstacle to the wave. For instance, a coastal strip of about 3 km is assumed as the inundation distance for a wave height of about 15 m at coast line. This information is integrated with available information on topographic elevation obtained from Digital Terrain Models (DTM), hence comparing topographic elevations with expected inundation depth profiles from the coastal line to the inland. Conclusions. The main aim of this project is to improve the knowledge on the structural vulnerability of existing masonry and RC residential buildings built along the Italian coast under tsunami loads, using a large scale approach. The first step has consisted of a state of the art review on tsunami damage reports and available design codes and guidelines. Collapse mechanisms of infill walls in RC structures and masonry under tsunami loads have been analyzed. Fig. 1 - Design tsunami pressure distribution.