Headed bars can assist in alleviating steel congestion and are commonly used in areas where development hooks or traditional reinforcement development lengths cannot be achieved. In this study, 30 exterior beam-column joint specimens without transverse reinforcement were tested to measure anchorage strength with respect to anchorage configuration and embedment length. The anchorage behavior of bars terminated with a head and with a 90-degree hook was investigated and compared with each other and existing models. Tensile load was directly applied to the bar and the same amount of compressive load was applied to the compressive zone of an idealized beam. Findings show that existing models based on idealized failure modes do not properly predict the concrete contribution to anchorage strength of headed bars terminated in exterior joints. The anchorage strength of the headed bars consisted of a combination of head bearing and bond. A specific model complying with the given condition of the anchorage zone should be used since failure modes of headed bar anchorage are varied with given geometric and material conditions. A new model is proposed that conservatively estimates the anchorage strength of the headed bars terminated within exterior beam-column joints with sufficient side cover.
