Strut-and-tie models and failure mechanisms for bar development in tension-tension-compression nodal zone

Strut-and-tie models and compatible failure mechanisms for bar development and anchorage failure in a tension-tension-compression (TTC) nodal zone are presented on the basis of the classical theory of plasticity, in particula r the normality rule, and the lower and upper bound theorems. The concrete is assumed as a rigid-perfectly plastic material obeying the modified Coulo mb failure criteria with zero tension cut-off, and for bar/concrete interfa ces, the simplest possible yield condition is assumed. The strut-and-tie mo dels presented herein assume uniform compression fields, and the upper boun d solutions introduce a new flexural type of failure mechanism for concrete crushing failure. The strut-and-tie models identify different failure mode s related to bond strength and dependent on materials strength and geometry .