GNGTS 2018 - 37° Convegno Nazionale

326 GNGTS 2018 S essione 2.1 According to the Japanese approach, the tsunami force depends on one parameter only, i.e., the inundation depth, which can be obtained by numerical simulations or hazard maps. Coherently with the goals of the present research project, the Japan guidelines approach was used, due to the large scale approach needed. In general, in the analysis, a linear (triangular) load pattern is assumed on the structure with a variable inundation depth and a constant slope. The inundation depth is increased to reach a specific damage level. For masonry buildings, local mechanisms activation is analysed accounting for the high variability of considered material. In particular, in-plane and out-of-plane mechanisms are studied. Shear and flexural failures are analysed as principal in-plane mechanisms, while horizontal and vertical bending mechanisms are considered as out-of-plane mechanisms. After the geometrical model generation, a flanged wall is extracted to analyse in-plane mechanisms (Parisi et al. , 2013), while a wall between two orthogonal walls is considered to study the out-of-plane mechanisms (Belliazzi et al. , 2018). The load condition is characterised by a triangular or trapezoidal pressure distribution, depending on the relationship between the maximum inundation depth and wall height. The analyses are developed entirely in Mathworks Matlab considering a large number of structural models for each masonry and RC building classes. Conversely, for RC structures the global behaviour is investigated under the triangular/ trapezoidal lateral load distributions caused by the tsunami. The analysis has been performed on single plane RC frames extracted from a three-dimensional structure. The interactions between the structural and non-structural components (i.e., masonry infills and partitions) are considered during the analysis in terms of both load distribution and damage level. A distributed plasticity model has been adopted for the RC members to observe the damage evolution under tsunami loading. Fragility curves and structural response. In the SPOT project, both empirical and mechanical fragility curves are studied. The empirical ones are available from international literature and based on past tsunamis, while the mechanical fragility curves are based on the aforementioned mechanical models. In particular, mechanical fragility curves are derived from structural analysis results using nonlinear least squares regression and a lognormal probability density function. The least square estimation method is based on estimating parameters by minimizing the squared discrepancies, S, between observed data, y i , and their expected values, f(x i ), lognormal function related to parameters β, i.e. mean and standard deviation. Main empirical fragility curves available in literature are referred to tsunami events occurred in Indonesia in 2004, Samoa Islands in 2009 and Japan 2011. These curves are strongly dependent on materials quality and inland characteristics. The Japanese database of damage Fig. 1 - Design tsunami pressure distribution.