As in many European countries, today in Italy there are few possibilities to design and build new dams. In particular, the construction of buttress (both solid or hollow) or multiple arch/slab dams is practically abandoned because they have shown in time several problems, namely cracks. On the other hand, there is a strong need to keep existing dams in safe service conditions, considering also the effects of seismic loadings, not foreseen during the design.

In order to define the activities and instruments which can be taken into account to supervise the health of an existing infrastructure, it is necessary to verifies the external acting forces and the structural response to these loads. For this purpose, also the mathematical model of dam-rock-reservoir is an important step in this procedure.

The Italian standard (D.M. 26 June 2014) is indeed focused into this aspect by suggesting the development of a reference dam model (e.g., based on the finite element method), able to analyse the response of this hydraulic structure under static and seismic actions, higher than those applied in the design phase, thus leading to more stringent conditions.

Therefore, the finite element models are used to evaluate and predict possible structural deterioration, which can imply abnormal behaviour and consequences, such as, for example, cracks and displacements due to environmental conditions (thermal or chemical phenomena) and aging.

First, this article presents an overview of the problems concerning buttress or multiple arch/slab dams and highlights the importance of the numerical models, which allow to study their safety under seismic loadings. Then, finite element analysis of an Italian multiple arch dam, subject to static and seismic loads, is presented.

The response of this hydraulic structure is studied considering different results: principal stresses, compared with standard limits; tensile damage and sliding coefficient of horizontal sections (defined as the ratio between horizontal and vertical forces), which must both be less than one; eccentric axial force analysis.