Page - 13 - in Book of Full Papers - Symposium Hydro Engineering

COMMISSION INTERNATIONALE DES GRANDS BARRAGES ------- VINGT-SIXIÈME CONGRÈS DES GRANDS BARRAGES Autriche, juillet 2018 ------- CURRENT CHALLENGES OF SEISMIC NUMERICAL MODELLING FOR DAMS: SOME ITALIAN EXPERIENCES Massimo MEGHELLA Member of ICOLD Committee A “Computational Aspects of Analysis and Design of Dams”. Sustainable Development and Energy Sources Department – Structures, RICERCA SUL SISTEMA ENERGETICO RSE S.P.A. ITALY EXTENDED ABSTRACT The dynamic FEM analysis is currently the most effective tool to simulate the seismic response of dams. However, as the seismic forces increase up to the level of intensity typically corresponding to MCE, the complexity of the models and the computation time increase dramatically, having to take into account the non-linear behaviour of both materials and interfaces (joints and pre-existing cracks). At the same time, the overall models uncertainty increases, which in combination with the lack of information on the real response of dams when subjected to strong earthquakes, makes models calibration and subsequent seismic analysis a very challenging, expensive and often impractical task. To cope with that, RSE adopted and further developed, a simplified dynamic method - the Endurance Time Analysis method (ETA) - which allows drastic reductions of the computational effort, to analyze the non-linear response of several large concrete dams in Italy and to obtain their “capacity curves” ranging up to collapse. In such way, even if the overall model uncertainty is still not properly addressed and quantified, the comparison of such curves within the dams portfolio allowed to develop simplified “risk indexes” to rank their relevant seismic risk, so that resource allocation for safety assessment can be definitely optimized. 13