Curved concrete crownwalls are commonly installed on vertical breakwaters in deep water to mitigate wave overtopping. This study compares the hydraulic and structural performance of fully curved and recurved crownwalls under impulsive wave loads induced by non-breaking waves, known as Confined-Crest Impact. Using one-way coupled numerical simulations in OpenFOAM and structural analyses in DIANA FEA, we assess the pressure fields and structural responses of the two geometries. Results reveal that while the fully curved crownwall significantly reduces overtopping, it experiences wave forces up to 2.5 times greater than the recurved crownwall, along with longer pressure impulse durations, leading to amplified tensile stresses and higher risk of cracking. In contrast, the recurved crownwall, despite localized peak pressures, benefits from a broader cross-section and linear stress distribution, resulting in better structural performance. These findings underscore the importance of integrating dynamic structural analysis in crownwall design to balance hydraulic efficiency with structural resilience.

Several failures of recurved concrete crownwalls have been observed in recent years. This work aims to get a better insight within the processes underlying the loading phase of these structures due to non-breaking wave impulsive loading conditions and to identify the dominant failure modes. The investigation is carried out through an offline one-way coupling of computational fluid dynamics (CFD) generated wave pressure time series and a time-varying structural Finite Element Analysis. The recent failure of the Civitavecchia (Italy) recurved parapet is adopted as an explanatory case study. Modal analysis aimed to identify the main modal parameters such as natural frequencies, modal masses and modal shapes is firstly performed to comprehensively describe the dynamic response of the investigated structure. Following, the CFD generated pressure field time-series is applied to linear and non-linear finite element model, the developed maximum stresses and the development of cracks are properly captured in both models. Three non-linear analyses are performed in order to investigate the performance of the crownwall concrete class. Starting with higher quality concrete class, it is decreased until the formation of cracks is reached under the action of the same regular wave condition. It is indeed shown that the concrete quality plays a dominant role for the survivability of the structure, even allowing the design of a recurved concrete parapet without reinforcing steel bars.