The mechanical anchorages of main bars in beam-column joints of reinforced concrete structures are tried to use in some construction systems. In these systems, the nuts with small flange which can be arranged at minimum required spacing are used as mechanical anchorages, but the design concept of the mechanical anchorage in reinforced concrete structures is not established yet. Ninety eight pull-out tests have already been carried out to clarify the development mechanism of the mechanical anchorage and to evaluate the ultimate anchorage capacities. The equation to predict the ultimate capacity of the mechanical anchorage is proposed in this paper. The predicted capacities agree with the experimental ones which were obtained in this experimental study or in previous experimental studies by other facilities.
