Steel structure shapes and members: Structural steel is a versatile material that can be fabricated into many different shapes to support different needs. Various structural members are used to manufacture a wide variety of cross section shapes and sizes.
In
steel detailing, it is important to understand the standard steel structure shapes and members, as well as the ability to customize structural steel to fit your unique design and support needs.
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| Fig 1: Structural steel shapes |
The cross-sectional views of the W-, S-, and C-shapes are illustrated in Fig 1.
The W-shape has parallel inner and outer flange surfaces with a constant thickness, while the S-shape has a slope of approximately 17 degrees on the inner flange surfaces. The C-shape is similar to the S-shape in that its inner flange surface is also sloped approximately 17 degrees.
W-Shape
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| Fig 2: Wide Flange Beam |
The W shape is a structural member whose cross section forms the letter H and is the most widely used structural member. It is designed so that its flanges provide strength in a horizontal plane, while the web gives strength in a vertical plane.
Material Grade: ASTM A992
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.
Applications: Used for beams, columns, piles, bracing and other heavy applications.
Tee
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.
Bearing Pile
The bearing pile (HP-shape) is almost identical to the W-shape. The only difference is that the flange thickness and web thickness of the bearing pile are equal, whereas the W-shape has different web and flange thicknesses.
HSS (Hollow structural section)
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| Fig 3: HSS (Hollow structural section) |
These square or rectangular sections are used most often as columns, but may also be used as beams, bracing or other applications.
Material Grade: ASTM A500 Grade B
Example : HSS6x4x1/4 where, 6 and 4 are the actual width and depth in inches, and 1/4 is the wall thickness in inches.
Structural Pipes
Circular pipe is used most often for columns, handrails and guardrails.
Material Grade: ASTM A53 Grade B
C-Shape or Channels
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Fig 4: Steel channel
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The C-shape (American Standard channel) has a cross section somewhat similar to the letter C.
Material Grade: ASTM A36
Channels are identified by their nominal depth and weight per foot. An example of a channel is C10x30 where
"C" indicates channel, 10 is nominal depth of the channel in inches, and 30 = weight in pounds per linear foot.
These "C" shaped members are used for beams, built-up columns, bracing, secondary framing and other light to medium-duty applications.
It is especially useful in locations where a single flat face without outstanding flanges on one side is required. The C-shape is not very efficient for a beam or column when used alone.
Angles
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| Fig 5: Steel Angle |
An angle is a structural shape whose cross section resembles the letter L. Angles have either equal legs or unequal legs.
Example - L4 x 3 x1/4 where 4 and 3 are the actual leg dimensions in inches
and 1/4 = angle thickness in inches.
Material Grade: ASTM A36
The dimension of the legs should be obtained by measuring along the outside of the backs of the legs. When an angle has unequal legs, the dimension of the wider leg is given first.
Used for lintels, bracing, built-up beams and columns, secondary framing and other light-duty applications.
Structural 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.
Material Grade: ASTM A572 / A36
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.
Conclusion
All shapes have their uses and can work together to create a strong support for your next fabrication project. Experience is key to the success of any fabrication project.
