Rigid framing connections for tubular columns

Abstract

This paper presents the design and development of rigid framing connections between wide flange beams and tubular columns for the case where the beam flange is substantially narrower than the column face. The present report is a sequel to a previous paper dealing with a connection in which the beam flange and the column face are of equal width.In the connection proposed here the transfer of flange stress from the beam to the sides of the column is effected by means of coped strap angles while transfer of shear to the column face is done through welded double angles.The experimental program comprised 15 specimens, including 2 standard rigid joints introduced to give a comparison basis for the [Formula: see text] (moment–rotation) curves.The results indicate that, in the case of a beam flange narrower than the column face, both special attention to the geometrical design of the strap angles and provision of a web connection (not required in the first case) are necessary to ensure that brittle fracture will not take place in the strap angles. A connection is then obtained which can develop the plastic moment MP and sustain appreciable inelastic deformation and is therefore suitable for plastically-designed frames.The rigidity of the connection, slightly less than that of a standard joint to a wide flange column, makes it a 'nearly rigid' connection.Exploratory analysis of the effect of that relative loss of rigidity on the sway behaviour of multi-story frames shows that, while this influence should not be critical for frames of the height that would normally be possible with the currently-available hollow structural sections, it may be significant enough to warrant investigation of P-Δ effects.A design procedure is proposed in the Appendix.