An overview of the typical problems concerning buttress, hollow gravity and multiple arch/slab dams is presented, emphasizing the support that advanced numerical modelling can provide for the evaluation of their safety and for the definition of the most effective interventions to guarantee long-term safety conditions.

Even if the construction of this type of dams is nowadays practically abandoned, the problem of assessing their safety remains an important and challenging issue considering the obsolescence of most existing structures of this type and the peculiarities connected with their structural behavior.

In the Italian context there are numerous cases of this type of works. The problems connected with these structures are well-known: cracks, degradation associated with environmental conditions and aging. Other criticalities are related to compliance with current legislation which requires the verification of more stringent conditions not foreseen in the design phase (higher seismic loads).

In this paper the application of the extended finite element method to evaluate the propagation of cracks in concrete dams and the seismic reassessment of an Italian multiple arch dam are discussed.