Pending that the STRETTO COMPANY and the EUROLINK CONSORTIUM give substance to the commitments undertaken with the social and professional forces of the city, regarding the certain forecasts of economic and employment consequences of the so-called “bridging industry”, this Order intends to make its own technical contribution by delivering to the SS .LL. some considerations and observations emerged following the examination of the “Designer’s Report integrating the 2011 Final Project” approved on 15 February 2024 by the Board of Directors of the Strait of Messina.
In detail, recalling the equal recommendations of the Scientific Technical Committee, it means that the designer’s report does not integrate the definitive project with a seismic evaluation of the project and updating of the structural calculations to the current NTC 2018 technical standards, postponing everything to the subsequent executive design. And therefore, in light of the current anti-seismic legislation, to date the definitive project has not been updated.
The adaptation to the NTC2018 technical standards, referred to in the decree of the Minister of Infrastructure and Transport of 17 January 2018, and the consequent changes to the geological modeling and geotechnical characterization will require that during the Executive Design the related structural checks respond to much more stringent criteria stringent and rigorous and therefore, equally recalling the contents of the CTS report, it will be necessary:
1. also use for the seismic actions designed for the Crossing Structure accelerometer recordings of earthquakes occurred in the world in the last two decades compatible, in terms of magnitude and failure mechanism of the fault, with the seismogenic characteristics of the Strait area;
2. carry out seismic analyses at the step of the Crossing Work also using time histories generated through appropriate latest generation physics-based models to consider the non-synchronism of the seismic motion, applying unitary combination coefficients for the three components of the seismic motion;
3. complete the tectonic geo-seismic data and the reference frameworkexpanding the relevant bibliography, considering, among other things, also the most recent European seismic hazard model (ESHM20);
4. refer to the “Guidelines and Criteria for Seismic Microzonation” (MS Working Group 2008), for the use of the studies seismic microzonation available;
5. also use the data deriving from the MaGIC 1 and MaGIC 2 Projects for the insights into the geology of the seabed of the Strait of Messina and adjacent sectors; such data available on the platform of the MaGIC1 project, and its extension MaGIC 2. The project, financed by the Department of Civil Protection, as part of a Framework Program Agreement with the National Research Council (Cnr), has the objective of define the danger of the Italian seabed, to improve risk mitigation activities and the management of emergency situations.
6. plan and execute, for the purposes of geotechnical design, further triaxial tests on undisturbed specimens (determination of hydraulic and mechanical properties of soils) taken at the different depths of interest, and tested at confinement values that cover the ranges of effective tensions representative of all the loading conditions used in the checks and analyses;
7. plan and execute programmed triaxial tests with suitable load pathsthe results of which can also be used for a better quantification of the initial stress state in FE modeling, overcoming the assumptions on previous load histories on the two sides;
8. quantify experimentally the dilatancy angle of the granular media involved and of the stiffness in the entire range of expected effective tensions, for the latter also through 1D compression tests;
9. to verify the performance of the elasto-plastic constitutive models used in EF simulations through their ability to reproduce the response of the materials observed in triaxial tests (also in extension) and oedometric tests, also paying attention to possible softening;
