Introduction. A quick-assembly contact beam-to-column joint based on the dovetail system is considered in the article. During installation, the beam is seated by its support ribs in sockets manufactured and welded to the column under factory conditions. Longitudinal displacement of the girder is prevented by filling the erection gaps with shim plates. This solution provides a simple and reliable connection between an I-section girder and a column made of a square cold-formed welded hollow section.

Materials and methods. The kinematic method of limit equilibrium was used to determine the limiting bending moment Mlim and the beam fixity coefficient C in the joint. Assuming that plastic deformations can significantly exceed elastic deformations, the steel stress-strain diagram was idealized as that of a rigid-plastic body. It was also assumed that the yield lines of the socket plates are linear plastic hinges along which only moment vectors act; the plates were considered rigidly fixed along two adjacent edges and free along the other two adjacent edges.

Results. The actual bending-moment diagram was constructed for a beam elastically restrained at both ends and loaded by two concentrated forces arranged symmetrically with respect to the supports; a formula was obtained for determining the support rotation angle φ.

Conclusions. The comparative analysis showed that when 5 mm thick plates are used in the support socket, the joint behaves almost as a hinge; when 10 mm thick plates are used, it behaves as a semi-rigid joint. The proposed contact beam-to-column joint can be recommended for use in design practice.