GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 2.1 325 classes are considered based on available public databases and specific surveys performed between November 2017 and February 2018 in Calabria region. The geometry and the material mechanical proprieties are generated with a probabilistic approach, in particular based on Monte Carlo simulations. For each model (geometry), the structural and non-structural elements are defined according to simulated design, based on codes and practice of the different construction periods in the analysed areas. The results of the structural analysis provide mechanical fragility curves based on Italian buildings data, for each representative building class. Damage scenarios and potential human (in terms of people exposed to building stock damage) and economic loss estimates have been evaluated, and the results managed through a geographical information system ( GIS ). Data collection on Italian coastal buildings. For the analysed areas, information about the structures, such as number of storeys, structural typology (masonry/RC) and construction periods, average building areas, residential population, can be retrieved from census databases of the “ National Institute of Statistics ” ( ISTAT ) and from further more refined databases mainly acquired during post-earthquake surveys by civil protection and other agencies. A normal distribution with a mean and standard deviation is considered for several parameters of masonry and RC buildings, according to GNDT (“ Gruppo Nazionale per la Difesa dai Terremoti ”) database. In particular, for masonry buildings, information such as inter-storey heights and floor loads are defined for five different masonry substrates. For RC buildings, concrete and steel mechanical properties distributions and bays length are provided as well. Construction periods related to the historical modification of building codes and seismic maps are important factors for the correct definition of the structural features of the analysed residential buildings. For masonry buildings, empirical design formulas, derived by Rondelet, Muller, Breymann, etc. are considered dating to the mid-nineteenth century. Historical codes for gravitational and seismic loads have been also consulted, such as Law n. 219 of 1981, Ministerial Decree of 16 November 1996, Building Code NTC 2008, etc. Similarly, for RC buildings, the historical codes R.D.L. n. 2229 of 16/11/1939, R.D.L. n. 2105 of 22/11/1937 and Ministerial Decree n. 40 of 3/3/1975 are considered for the characterization of the structures. Structural modelling and analysis of existing buildings under tsunami loads. The modelling of the tsunami effects on structures is extremely complex due to the high degree of uncertainties in the wave characterization and associated loads on structures. The principal available codes and guidelines have been developed in U.S.A. and Japan: • FEMA P-646 (Federal Emergency Management Agency: Guidelines for Design of Structures for Vertical Evacuation from Tsunamis); • ASCE 7-16 (American Society of Civil Engineering: MinimumDesign Loads for Buildings and Other Structures) it is the most recent design code for tsunami forces; • SDRTEB (Structural Design Requirements for Tsunami Evacuation Buildings). In the first two documents, which were developed in the U.S.A., the tsunami effects are defined by several scenarios and forces (e.g., hydrostatic, drag, buoyant, surge, impact, debris impact forces). Every force depends on several parameters (e.g., inundation depth, flow velocity and maximum momentum flux) characterized by high variability in hazard maps, numerical simulations and simplified equations. The third document is a Japanese guideline based on the assumption that the tsunami effects on structures can be modelled adopting only one equivalent hydrostatic load (Fig. 1) that indirectly includes the effect of both hydrostatic and hydrodynamic loads. In particular, the fictitious design inundation depth is assumed to be equal to three times (i.e., η=3) the expected inundation depth, if no specific tsunami energy dissipation structures, namely seawalls, are installed (Fukuyama et al. , 2011). It is assumed that the design inundation depth can be scaled down, depending on the presence of such dissipative structures. If there are tsunami energy dissipation structures, which are not common along the Italian coasts, the inundation depth can be reduced strongly, even halved or more.