The objective of this work concerns the analysis and design of an existing deep beam with a high thickness in reinforced concrete, according to the standards defined in the Eurocode. The structure is inserted in a hydroelectric plant in the Alentejo region of Portugal. The initial data is used to define the geometries parameters and the loads based on the deep beam. The analysis began with a study of its environment, in order to determine the different actions and the loading for the ultimate limit state and the state of service. The analysis is followed by a study of numerical values known for simple cases in the elastic domain, then by an elastic analysis with finite element software IConc and finally with the strut and tie models. During the dimensioning step, the modeling of the structure was performed by the SAP2000 finite element software, in the order to evaluate the stresses resulting from the defined actions. This is followed by performing of the safety checks and reinforcement calculations for the ultimate and serviceability limit states, for the deep beam, but also for the columns. A detailed reinforcement plan could thus be created. Subsequently, thanks to the considered reinforcement arrangement, a verification at failure was performed by using the IConc software again and assuming an increase in the mobile loading. An optimization of the thickness of the web was also reflected, as well as the possibility of removing one of the columns, with the establishment of prestressing.