Physical and mechanical aspects of failure in concrete and concrete structures

The object of this lecture is to examine physical and mechanical aspects of failure in concrete and concrete structures in order to focus attention on the principal difficulties that lead to error in predicting behaviour. In doing this, a deterministic view is adopted so that difficulties of defining the loading and accident conditions are ignored. In addition, a physical view of failure is adopted in contrast to that of the designer who may choose to define failure in terms of limits on stress, strain and displacement which are chosen to provide a safe lower bound to structural performance. As background to this discussion, first is looked at the mechanics of failure of plain concrete. Following this, attention is given to size effects, the role of initial conditions, load path dependence, brittleness and the provision of ductility