Finite element modelling of cracking in nuclear reactor concrete containment buildings.

Containment buildings are required to protect the public from the effect of radioactivity released by an accident to the nuclear power plant. they must be designed to minimize leakage through cracks in building wall and so methods are needed which can predict the geometry of the cracks including their widths. This study provides a realistic model of bond action between deformed reinforcing bar and concrete which uses interface element based on measured bond characteristics combined with radial constraints to simulate wedging action. It is shown to be capable of accurately predicting stress, strain, and crack geometry in typical reinforced concrete components for a variety of loading conditions. Of particular note is the ability of the model to simulate the deterioration in bond brought about by prior application of cyclic load of high amplitude. Similitude requirements for physical models of reinforced concrete structures are examined in the light of available experimental results and predicted values. The need to correctly scale the fracture energy to ensure proper representation of the bond characteristics is demonstrated. The study ends with an examination of the suitability of higher order elements which adopt a softening characteristic to represent the effect of a primary crack and its use in analysis of a typical nuclear reactor containment building.