The softening rotation of reinforced concrete members

The ductility or rotational capacity of reinforced concrete members is a very important parameter for the safe design of RC structures as it controls: the ability of the structure to redistribute moment and fail gradually; the drift and, hence, magnified moments in the columns; and the ability to resist seismic and blast loads. One component of the rotational capacity is that due to concrete softening. In this paper, a softening rotation model is developed based on recently published fundamental research in which softening is considered to be a mechanism rather than a material property. The approach is validated from both published and new concrete prism tests and shows good correlation.