Steel is a common material used through the construction industry. Its primary purpose is to from a skeleton for the building or structure essentially the part of the structure that holds everything up and together. Steel has many advantages when compared to other structural building materials such as a concrete, timber, plastics and the newer composite materials. Structural steel shape, size, composition, strength, storage, etc., is regulated in most industrialized countries.
1. Wide Flange 
The typical “I Beam” used in construction. Example – W18x35, where “W” = Wide flange, 18 = nominal depth of member in inches, and 35 = weight of beam in pounds per linear foot. Used for beams, columns, piles, bracing and other heavy applications.
2. Angles 
Either equal legs or unequal legs. Example – L4x3x1/4 where 4 and 3 are the actual leg dimensions in inches and 1/4 = angle thickness in inches. Used for lintels, bracing, built-up beams and columns, secondary framing and other light-duty applications.
3. Steel Channels 
These “C” shaped members are used for beams, built-up columns, bracing, secondary framing and other light to medium-duty applications. An example of a channel is C10x30 where “C” indicates channel, 10 is the actual height of the channel in inches, and 30 = pounds per linear foot.
4. Steel Pipe 
Circular pipe is used most often for columns. Comes in three categories based upon diameter and wall thickness, and are “standard weight”, “extra strong” and “double extra strong”. The double extra strong pipe is the strongest because it has the thickest walls. Example – Standard Weight 4″ dia. pipe.
5. Tube Steel 
These square or rectangular sections are used most often as columns, but may also be used as beams, bracing or other applications. A typical example is TS6x4x1/4 where TS = Tube Steel, 6 and 4 are the actual width and depth in inches, and 1/4 is the wall thickness in inches.
As of 2003, tube steel is now referred to as “Hollow Structural Section” (HSS) by the American Institute of Steel Construction. A typical designation is HSS6x4x1/4.
6. Plates -Flat pieces of steel cut to size. Generally in the range of 1/8″ thick up to 6″ thick. Used as column base plates, built-up beams and columns (i.e., plate girders), connection pieces (I.e., gusset plates, weld plates, etc.), and any other application where specific sized pieces are required. Example – PL 6x4x3/8 where 6 and 4 are length and width of the plate in inches and 3/8 is the plate thickness in inches.
7. Cut Sections -Typically these are wide flange sections that are cut in half to form a “T” section. Used for lintels, beams, bracing and columns. Example – WT7x19 is a section cut from a W14x38 wide flange.
