Anchorage systems are classically used in reinforced concrete structures to bear external equipment. They are composed of an anchorage plate, which allows the attachment of the equipment and of steel dowels, which ensures the relation into the structural reinforced concrete. In design practice, the stiffness of the anchorage plate is considered to be infinite but in reality, the system can deform, resulting in a non-uniform distribution of the forces into the dowels. The objective of the PhD thesis is to evaluate, through the simulation, the potential impacts of the stiffness of the anchorage plate on the mechanical properties of the anchorage system, up to the design practice. It will include the identification of the expected loads and failure modes through a state-of-the-art, the development of a reference modelling strategy in order to represent the main mechanisms and a simplification of this refined model up to the construction of response surfaces for some well-chosen quantities of interest, which are more suitable for engineering practice. This PhD thesis will be done in collaboration with EDF and Paris-Nanterre University.