Modelli variazionali per la progettazione e la diagnosi dell’evoluzione e dello stato di ammaloramento di dighe in calcestruzzo.

This research investigates the complex interplay between structural mechanics and material degradation in civil engineering and soil. The focus is on two primary areas: the long-term behaviour of concrete dams subjected to aging and the limitations of linear models in capturing seismic response. % % Aging-induced deterioration in concrete dams is primarily attributed to the diffusion of deleterious substances, which subsequently trigger internal chemical reactions. This study proposes a unified hemivariational framework for investigating damage and deformation in concrete dams subjected to aging-related processes. The model incorporates both one-dimensional (Timoshenko beam) and two-dimensional representations of the dam structure. % A novel aspect of the proposed approach is the introduction of an "external distributed aging fluid influx pressure" as a dual of the concentration of the aging fluid. This pressure drives the inward diffusion of the aging agent, which is coupled with the evolution of damage. Parametric analyses are conducted to evaluate the influence of diffusivity and damage-concentration coupling term on the damage progression and service life prediction. % The results indicate that the dam's shape significantly impacts stress distribution and, consequently, damage initiation and propagation. For the bi-dimensional case a more refined damage threshold is introduced to account for the distinct compressive and tensile behaviours of concrete. The proposed modelling approach provides a robust framework for assessing the long-term performance and safety of aging concrete dams, with potential applications in structural health monitoring and life cycle management. % The same theory is also used to investigate a particular phenomenon we called \textit{apparent} creep because the underlying mechanism is analogous to the processes occurring subsequent to classical creep deformations. This phenomenon, observed in a two-dimensional polymeric beam, exhibits characteristics akin to creep, as evidenced by numerical simulations demonstrating increased displacements under constant external loading conditions due to fluid ingress into the domain. % % % The presence in soils of deteriorating fluids induce modifications of its mechanical characteristics. However, it is important to preliminary investigate. % Additionally, one more research investigates the limitations of linear models in capturing the complex behaviour of geomaterials subjected to extreme loading conditions, such as those induced by seismic events. The research challenges the conventional linear paradigm in geophysics and civil engineering, particularly in the context of seismic events. % This research investigates the influence of non-linear material behaviour on seismic response. A non-linear viscoelastic model is developed to capture large deformations near geological discontinuities, commonly observed in complex geological settings (such as those observed in the Aterno River Valley). Numerical simulations demonstrate the critical role of non-linearity in accurately predicting ground motion characteristics, including frequency content and amplitude. By combining these factors, the research provides a comprehensive framework for enhancing the reliability and accuracy of seismic hazard assessment and structural analysis. The findings contribute to the development of advanced computational tools for mitigating seismic risk and ensuring the safety of critical infrastructure.