Steel components in bending ? Beam joints. Component method

In practice, bent connections in steel construction are designed in two different ways.

The first is to guarantee continuity between two beams, or between a beam and a column. These connections are made either by bolting plates perpendicular to the beams, or by bolting covers to the flanges and web of the beams. They transfer a significant moment.

The second design consists in not ensuring continuity at the fasteners, thus leaving the beam free to rotate on its supports. These connections, which are fairly simple to manufacture and install, are often made using double angles bolted to the load-bearing element and the supported beam.

In France, the adoption of the Eurocodes has led to changes in the way this type of connection is calculated, notably with the introduction of the component method. While this method provides a means of calculating the resistance of beam connections (bending moment, shear force), it also introduces the concept of semi-rigidity, which makes it possible to characterize the deformability of connections and their influence on the overall behavior of the structure. Consequently, it is necessary to justify the modeling assumption for connections which, in practice, are generally considered to be articulated or embedded.

In this article, the component method is presented in a general way, before being applied to beam connections using bolted end plates. The case of hinged beam connections is then considered. For each of these two types of connection, the different constructive arrangements used in practice are explained, and the calculation methodology is illustrated by means of simple examples.

Column foot connections, another particularly important category of fastener, are the subject of a separate article (see [C 2 557] ).