Study of the behavior of post installed fasteners in civil engineering structures of french nuclear installations

International audienceWhen it comes to providing connection between different components, post installed mechanical fasteners always offer a suitable solution. The level of performances of these fasteners is nevertheless a concern, due to the consequences it may cause if they were inappropriately chosen. In order to avoid unexpected low performance of the fasteners, it is important to have a good knowledge of the mechanical behavior of fasteners to guarantee the durability and the efficiency of the structure. This issue is for instance raised in the case of French nuclear power plants for which the decision to extend the duration life is at stake . In addition, except for newly installed anchors, most fasteners used in nuclear power plants have not been specifically qualified to demonstrate their capacity to support seismic loading. In recent years, CSTB (Centre Scientifique et Technique du Bâtiment) carried out experimental tests on fasteners used in nuclear power plant. The results showed that the shear capacity of these anchors subjected to seismic load is relatively lower with respect to a static loading, which highlighted a need to study in more details their behavior. It should be noted that this qualification was not requested when the fasteners were installed.The scientific approach is to use two additional modeling to assess the fasteners behavior with seismic loading: At the fasteners scale, the concrete crack will be explicitly described by a discrete model and at the structure scale, a simplified model using generalized variables will be developed to represent the non-linear behavior of the fasteners. The parameters of this model will be defined by the discrete model. In this paper, only the part at the scale of the fasteners is presented.In order to complete the experimental results, a numerical study is proposed in this paper to predict the behavior and the capacity of the fasteners under various loading. This study was done using a discrete element method, which allows to explicitly represent the cracks induced by the seismic event and the associated mechanisms (initiation, propagation, closure and unilateral effect, friction). After a brief description of the discrete model, the new meshing procedure, taking into account complex geometries, is presented. Then, numerical results obtained in 2D and 3D for static loads and carried out on headed stud are discussed. Finally, they are compared against experimental data. The discussion focuses on the capacity and the limitation of a 2D numerical model, to predict the behavior of fasteners and the necessity to move to a 3D modeling