ABSTRACT
Steel is the most widely used structural metal. Its popularity may be attributed to the combined effects of several factors, the most important of which are: it possesses great strength, it exhibits good ductility, it has high stiffness, fabrication is easy and it is relatively cheap. Good examples of structural steelwork design seek to exploit each of these features to the full [1]-
Steel's high strength permits heavy loads to be carried by relatively small members, thereby reducing the self-weight of the structures. This reduction in dead load facilitates the construction of the large clear spans needed, for example in sports halls. At points of very high stress such as in the immediate vicinity of a bolt, yielding of the material will enable the load to be redistributed smoothly and safely; this process makes use of the property known as ductility. All structures will deform to a certain extent when loaded - even when such loading consists only of the structure's own self-weight. Because steel possesses great stiffness (as measured by its modulus of elasticity E) these deflections will not normally be large enough to require special consideration. Steel may be worked in the fabricating shop in a number of ways, for example sawing, drilling and flame cutting; it may also be joined together by welding. Finally the price of steel is substantially less than that of any possible competing metal; for instance aluminium costs about three times as much as the basic structural grades of steel.
