Path-dependent nonlinear analysis of a concrete reactor containment vessel subjected to internal pressure using a volume control technique

The so-called volume control method has overcome the drawbacks of the load controlled method and the displacement controlled method by adding a pressure node which has an increment of pressure as an additional degree of freedom to a finite element. In this paper, a nonlinear volume control finite element method has been developed for the nonlinear analysis of reinforced concrete containment reactor vessels (RCCV) and prestressed concrete containment reactor vessels (PCCV), which can predict the ultimate internal pressure capacity of a containment reactor vessel subjected to accidental internal pressure. A multi-layered shell element with a pressure node is adopted for analysis by utilizing a path-dependent crack model, and an orthogonal two-way fixed crack model along with an averaged in-plane 2D RC model and a prestressing tendon model for the layered shell elements. A reinforced concrete panel subjected to biaxial tension, and RCCV and PCCV subjected to internal pressure are also analyzed. Both applicability and validity of the proposed method are shown by comparing the results of volume control method with both experimental results and existing analysis results.