Structural Drafting

Siti Kamariah Md Sa’atSchool of Bioprocess Engineering, UniMAP

ERT 243 COMPUTER AIDED DESIGN AND DRAFTING (CAD)

STRUCTURAL SHAPES AND MEMBERS CLASSIFICATION: S shapes (formerly called standard beam or

I beam) C shapes (formerly called standard Channels) W shapes (formerly called Wide-flange shapes) M shapes (formerly called Joists and light

beams) Structural Tee L shapes or Angles Hollow structural section (HSS) Plates, Round and rectangular bars.

The steel sections classification mostly used in North America:

Values are presented in either Imperial (inch-pound) units or SI (metric) units. The data presented in each system isn't exactly equal; therefore, each system should be used essentially separately. Combinations values from these systems aren't allowed. (ASTM A6/A6M).

The steel sections classification mostly used in North America:

I-beams (I-shaped cross-section)W - Wide flange steel beam (I-shaped cross-section) have parallel flange surfaces.S - American Standard Beam (I-shaped cross-section) have a slope on the inner flange surfaces.HP - Bearing Pile (H-shaped cross-section) have parallel flange surfaces and equal web and flange thicknesses.M - Miscellaneous shapes cannot be classified as standard i-beams (W,S,HP), available from a limited number of manufacturers.

The steel sections classification mostly used in North America:

Channels (C-shaped cross-section)C - American Standard Channels have a slope on the inner flange surfaces. MC -American Miscellaneous Channels cannot be classified as standard channels, available from a limited number of manufacturers.

Angles (L-shaped cross-section)L - shapes are equal leg and unequal leg angles.

Steel section types

Structural Steel Shapes

Table Properties of common structural steel shapes

Table 25-2

Mill Tolerances You should understand certain permissible deviations

that are brought about the manufacture of structural steel.

These permissible deviations from AISC manual, in mill catalogsnand from the lengths specified by purchaser, are referred as mill tolerances.

Factor considered the necessity of a mill tolerance are:1. high speed of rolling operation required to prevent the

metal from cooling before the process complete.2. the varying skill of operators in squeezing together the rolls 3. the mechanical factors 4. warping of steel in process of cooling5. the subsequent shrinkage in the length of shape was cut

while the metal still hot

Example calculation length + tolerances

W24x94 beam having 24 ¼ in depth. Depth at centerline could be 24 ¼ + 1/8 or 24 ¼ - 1/8 Width of flange could be 9 + ¼ or 9 – ¼ The beam ordered to cut in the mill as

55-ft length, it will received from fabricator with a length 55+ ¾ or 55 – ¾

Example calculation of minimum and maximum length of joint beams

Minimum length: (42’ – 3/8) + (35’ – 3/8) Maximum length: (42’ + 3/8) + (35’ + 3/8)

B1 B2W10

42’ 35’

The steel beams (sections) classification

used in UK. I-beams (I-shaped cross-section)

UB - Universal Beams (I-shaped beams) have parallel flange surfaces.J - Joists (I-shaped beams) have a slope on the inner flange surfaces.UC - Universal Columns are shaped sections have equal or near-equal width and depth.UBP- Universal Bearing Piles are shaped sections have parallel flange surfaces and equal (or near-equal) web and flange thicknesses, stocky webs and flanges.

C-Profiles (channels)CH - Taper flange channels.PFC- Parallel flange channels.

The steel beams (sections) classification

used in UK.

Angles (L-shaped cross-section). They are often used to carry tension loads and can be bolted or welded to other members.UE - Angles are unequal angles have legs of different lengths.E - Angles are equal angles have both legs of the same length.

A Hollow Structural Section (HSS) is a type of metal profile with a hollow tubular cross section. In some countries they are referred to instead as a structural hollow section (SHS). RHS - Hot finished rectangular hollow section.CHS - Hot finished circular hollow section. SHS - Hot finished square hollow section.

Structural Steel Shapes

Projecting structural shapes. A. I- or H-beam. B. Channel. C. Tee.

Table Properties of common structural steel shapes

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Connection

There are four basic connectors used in making structural steel connections. They are bolts, welds, pins, and rivets.

Type of Connection

Web connection