Exploring methods of stiffening joints involving steel hollow sections

Abstract

The use of steel hollow sections in recent years has increased greatly. Their increased use has been triggered not only by their aesthetic appeal, but also by structural advantages such as their high torsional rigidity and their suitability for plastic design. Connections with Hollow sections are difficult due to their inaccessible void at their centre. Solutions for this problem typically involve welding the sections, as in most trusses and welding sub-assemblages which are then bolted together. Moment resisting connections are exceedingly problematic since welding is usually insufficient to resist moment. The dissertation also reviews the joints currently used to connect square and Rectangular Hollow Sections. An appraisal of the latest developments in the use of hollow sections is presented with a particular emphasis on bolted connections. This dissertation proposes a new joint for connecting two square hollow sections. This connection is intended to resist moment and may be used in structures such as Portal Frames, Veerindeel Girders, and beam-column frames. The connection makes use of one-sided (blind) bolts. A theoretical model is presented for the design of the connection, with the expected failure modes and numerical values for the moment of resistance of the connection. Tests were carried out to verify the theoretical models presented. Two connections were tested to obtain a moment-rotation relationship and the ultimate moment resistance of the joint.