STRUCTURAL DESIGN FOR ARCHITECTURE

Structural Design for Architecture

Fig. 3.19 Cold-formed sections. Structural sections can

be formed by bending thin sheet. This allows more

complex shapes of cross-section to be created than is

possible with the hot-rolling process. The metal must be

relatively thin, however, so these are lighter sections with a

lower carrying capacity than hot-rolled equivalents.

the fabrication of sections with complex

geometries (Fig. 3.19) and 'tailor-made' cold-

formed sections can be produced for special

purposes at a reasonable cost. The sections

which are most commonly employed in build-

ing are Z-purlins, which are frequently used in

conjunction with frames of hot-rolled

elements, and profiled-sheet decking. Many

kinds of the latter are produced and they are

employed both as roof decks and, in conjunc-

tion with in situ reinforced concrete, as floor

structures. Another common use of cold-

formed sections is for the flanges of light

lattice beams and a number of proprietary

ranges of these are available. An example is

the Metsec range (Figs 3.20). These are

suitable for use as joists in conjunction with

loadbearing masonry or with main frames of

hot-rolled sections. They are also used to form

complete frames in situations where only light

loads are carried.

Cold-formed sections are much lighter than

hot-rolled sections and they have considerably

less strength than the latter. Their principal

application has been in single-storey struc-

tures; most cold-formed sections do not have

Fig. 3.20 Metsec beam.

This is an example of a

proprietary beam in

which cold-formed

sections of relatively

complicated shape have

been used for the flanges.

Elements like this are

highly efficient in resist-

ing load and are therefore

light. Their limited load-

carrying capacity makes

them most suitable for

use in roof structures.

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