Benchmark Finite Element Calculations for ASCET Phase III on a Reinforced-Concrete Shear Wall Affected by Alkali-Aggregate Reaction

Abstract

In this study, finite element (FE) analyses were conducted on a reinforced-concrete (RC) shear wall that is affected by an alkali-aggregate reaction (AAR), which were then applied for a benchmark studies in OECD/NEA/CNSI/ASCET (Organization for Economic Co-operation and Development/Nuclear Energy Agency/Committee on Safety of Nuclear Installations/Assessment of Structures subjected to Concrete Pathologies) Phases II and III assessments. A commercial software has been modified to account for this AAR expansion, which is affected by the stress field and change in physical properties of the concrete. The impacts of boundary conditions, modeling in two and three dimensions, and material properties on the load-displacement curve and crack patterns were carefully evaluated. Finally, although similar load-displacement curves and crack patterns were obtained, the peak load due to brittle failure of an RC shear wall affected by AAR could not be reproduced.Consequently, it was found that the rotation of the loading stub and anchoring procedure of the base stub were critical conditions for load-displacement relationship of RC shear wall, and meshing capturing the arrangement of reinforcement bars is crucial for FE analysis with two-dimensional (2D) condition, and finally, the occurrence of initial cracks and the loading capacity could not be clearly reproduced. This suggests that consideration of the placement of rebars and covering concrete in the mash setting in three-dimensional (3D) model affected the failure mode of the concrete. It is necessary to consider the possible failure mechanism and to reflect such features in numerical modeling.