Enriched Finite Elements for Crack opening and Fiber Slip

In the paper is proposed a novel enhanced elements that account for the interaction between concrete and rebars. It isa continuum element, in which steel fibers are embedded. An appropriate constitutive equation accounts for the slip (actually the CEB proposal is used); crack opening is simulated using a cohesive model that accounts for damage in the framework of the Elements with Embedded Discontinuities. A macro beam element is studied in details. Special shape functions are used that are close to the solution for the case the slip constitutive relation is linear. B-splines are shown to yield excellent results. Whenever a crack arises, a singularity is added, ruled by a cohesive constitutive relation, in order to provide the correct fracture energy.