Hollow rectangular structural steel sections have been used in structures since the advent of steel construction at the end of the nineteenth century. The first sections were built up by rivetting together plates and angles to form a box. Current practice is to weld together four or more plates, or to weld plates onto a rolled wide flange (W) section in order to form the built up box section. After World War II, rectangular sections started being manufactured from a single plate by a cold forming process.
classic column production
steps of classic column production
Built up box sections can be made to almost any dimension. Size and availability are limited by cost, the number of fabricators with the expertise to make these sections, and transportation and erection limitations.
disadvantages of classic column production
Hollow rectangular sections, both built up boxes and structural tubes, offer several advantages in building construction. These members are structurally efficient for compression, bi-axial bending, torsion, and long unbraced uniaxial bending. Of these conditions, compression is by far the most common. Box sections also generally occupy less space than W sections. Tubing is often small enough to be placed within a wall or partition, thus eliminating the need for protrusions. The hollow interior of boxes can be used to hide utilities, or can be filled with concrete for greater strength. Finally, when left exposed, tubing has a clean, sleek and pleasing appearance.
The availability of heavier jumbo steel wide flange sections, high strength steels, and the increasing use of high strength concrete may cause a decrease in use of the built up box member. However it is anticipated that manufactured tubes will continue to be used in one storey buildings, and in exposed architectural applications.