The Anchorage Behavior of Headed Reinforcement in CCT Nodes and Lap Splices

The behavior of headed reinforcement in concrete was studied using full scale tests of CCT nodes and lap splices. The mechanics of the anchorage behavior were observed and recorded to evaluate the manner in which the capacity of a headed bar is developed. The measured data were used to evaluate existing models of headed reinforcement anchorage as well as the ultimate limit state for anchored bars in CCT nodes. Observations from the CCT node tests provided information on the stages of truss development in a simple strut-and-tie model as well as the stress state of the concrete in the node and adjacent struts. Observations from the lap splice tests provided information on the mechanism of stress transfer between lapped bars. The results indicate that strut-and-tie modeling can be successfully applied to understand the behavior of non-contact lap splices and is necessary in determining the anchorage length of lapped bars. Observations of headed bar anchorage have shown that the final anchorage capacity consists of peak head bearing and reduced bond. A model for anchorage capacity was produced based on this concept. Finally, recommendations for structural concrete design using headed reinforcement were made.