Hollow structural section
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Hollow structural section (HSS) is a type of beam with a hollow rectangular cross-section. It is also called structural tubing or hollow structural steel, although it is available in other materials than steel. The corners are heavily rounded, to a radius of approximately twice the wall thickness. The wall thickness is uniform around the section. They are commonly used in welded steel frames where members experience loading in multiple directions. When the loading is more predictable, I-beams are usually a more efficient structural choice. The flat square surfaces of HSS can ease construction, and they are sometimes preferred for architectural beauty in exposed structures. HSS is commonly available in mild steel, such as A500 grade B, and aluminium alloy.
An alternative to HSS is pipe. See also structural steel.
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[edit] Manufacture
Square HSS is made the same way as pipe. During the manufacturing process flat steel plate is gradually changed in shape to become round where the edges are presented ready to weld. The edges are then welded together to form the mother tube .During the manufacturing process the mother tube goes through a series of shaping stands and cold form's the round HSS (mother tube) into the final round,square,or rectangular shape. Most American manufacturers adhere to the ASTM A500 standard, while Canadian manufacturers follow both ASTM A500 and CSA G40.21
[edit] Filled HSS
HSS is often filled with concrete to improve fire rating, as well as durability is increased. For example, barriers around parking areas bollards made of HSS are often filled, to at least bumper height, with concrete. This is an inexpensive (when replacement costs are factored in) way of adding compressive strength to the bollard, which helps prevent unsightly denting and bending.
[edit] Recent successful examples of the architectural aesthetics of HSS
HSS can be made into beautiful sculptural elements. Examples include the three new light stands that help to enhance the architectural beauty of Dundas Square in Toronto. The light stands are made of curved HSS of square cross section, and are finished in a high gloss white epoxy paint that nicely compliments the textured nonslip black granite surface from which Dundas Square is made.
