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Steel Designers' Manual - 6th Edition (2003)
864 Bearings and joints
(a)
(i) (ii)
(b)
Fig. 28.15 Radial and rotational movement. (a) Radial expansion from a fixed point,
(b) end rotation
amount of movement considerably facilitates joint construction as the discontinuity
in the structure is smaller. Similar joints are used in bridge work for
small-span bridges, or so-called ‘buried joints’ in the road surface.Typical examples
of joints suitable for movements within this range are given in Fig. 28.14.
They may be preformed units, but are more likely to be assemblies of proprietary
components arranged to suit the particular requirements of the detail and
its location.
(2) 25–300 mm movement: Joints capable of movements of this extent are more
common in bridge work, and are usually prefabricated units, although a simple
plate arrangement can be used in some cases (Fig. 28.16(a)). Two basic types of
prefabricated units are common. Figure 28.16(b) shows the first type, which uses
an elastomeric material in its construction to accommodate the movement.
Figure 28.16(c) shows the second type, which is suited to the larger movement
ranges. This type uses an arrangement of mechanical components supported on
stub beams to form a moving joint. Detailing of the structure must allow for the
space required by these units.
(3) >300 mm movements: Joints for movements of this magnitude are unusual and
will be tailored to particular requirements, e.g. expansion joints for suspension
bridge decks.
28.3.2.6 Required performance of the joint surface
The nature of effects acting on the surface of the joint should be considered. In
building structures, this will frequently be limited to environmental effects on