Chapter 23: Structural Drafting

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Chapter 23 Structural Drafting

• Structural engineering is generally associated
  with commercial steel and concrete buildings, and
  in some situations, it is also used for the
  structural design of residential buildings

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Structural Drawings

• Structural drafting techniques are generally the
  same as mechanical drafting usually they are a
  combination of mechanical and architectural
  methods used
• Structural drawings are usually independent of
  architectural drawings and other drawings

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Line work Lines used in structural drafting are
generally the same as those used in mechanical
drafting

• Lines may heavier or thinner than normal
  depending on the emphasis size of the drawing
• Dimension lines may be drawn with a space for the
  numeral or the numeral may be placed above the
  dimension line
• Dimension lines may be capped with arrowheads,
  slashes, or dots

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Lettering

• Structural lettering is generally slanted gothic
  style and freer in style than mechanical
  lettering
• Lettering heights
• All lettering, except titles 1/8 to 5/32
  (3-4mm)
• Titles 3/16 to ¼ (5-6 mm)

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Coordination of Working Drawings

• The structural drawings are a portion of a
  complete set of working drawings
• A page numbering system is used in order to
  organization each type of drawing on a commercial
  project (AIA Handbook of Professional Practices)
• The structural drawings can have a series of
  sheets that are numbered such as S1.1, S1.2
  S2.1, S2.2, S2.3 S3.1,S3.2, S3.3 etc.

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Example of How Drawing Elements Are Coordinated
Between Pages
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Laying out Details and Sections

• Details sections may be placed with the drawing
  where they relate or placed on a separate sheet.
• All Details should be grouped together and
  organized from left to right,and laid out in
  sequential order on the drawing sheet.
• Sections are laid out in the same manner with
  labels in alphabetical order.

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Concrete Construction Concrete is a mixture of
Portland cement, sand, gravel, and water.

• Concrete is the fundamental material for
  foundations
• Concrete is used in commercial sites for wall and
  floor systems
• Concrete can be poured or pre-formed into
  structural shapes

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Steel Reinforcing of Concrete Concrete alone has
excellent compression qualities but add steel and
the tension properties improve to make it stronger

• Reinforced Concrete Concrete poured around
  steel bars placed in the forms
• Rebar The steel bars
• The most common steel reinforcing is plane and
  deformed, in round or square bars

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Examples of Standard Structural Callouts for
Concrete Reinforcing

• Specifying Anchor Bolts
• (12)-3/4ØX12STD AB 24 OC W/3PROJ

• Specifying Rebar
• 4_at_12O.C.
• (25)8k_at_24O.C.
• HORIZ. AND 16 O.C.
• VERT 6_at_24O.C.EA
• WAY (or EW)

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Types of Concrete Construction

• Poured-in-place concrete
• Pre-cast Concrete
• Tilt-up Pre-cast Concrete
• Concrete Block Construction

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Concrete Structural Drawings

• Concrete material symbols are used where
  appropriate
• Rebar is shown as a very thick line or a thick
  dashed line in the longitudinal view and a round
  dot where the rebar appears cut
• When drawing concrete block structures details of
  the steel reinforcing patterns are shown

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Wood Construction

• Used in both residential and commercial
  applications
• Commercial applications include
• Partition Framing
• Upper-level Floor Framing
• Roof Framing

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Types of Wood Construction

• Heavy Timber Construction
• Laminated Beam Construction
• Note The drafters major responsibility is
  the drawing of the connection details for Heavy
  Timber Construction and Laminated Beams

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Engineered Wood Products

• I-Joists
• Laminated Veneer Lumber
• Rim Board
• Plywood Lumber Beams
• Stressed Skin Panels

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Standard Wood Structural Callouts

• Give the nominal (rough, before planning)
  cross-sectional dimensions for sawn lumber
  timbers
• 4x12,6x14
• Net dimensions of a glu-lam is followed by and
  abbreviation
• 6 1/8x 14GLB f2400
• If lengths (LG) is required for wood members,
  they are given in feet inches
• 6 ¾ x 18GLB x 24-0 LG
• Glu-lam beams with manufacturing numbers
• 6 ¾ x 18 22FV4

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Steel Construction

• Three Categories
• Steel Studs
• Prefabricated Steel Structures
• Steel-framed Structures

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Structural Systems The structural system is made
up of the frame that support the walls and roof.

• Wall System Horizontal Girts attached to the
  vertical structure and metal wall sheets attached
  to the girts.
• Roof System Horizontal Purlins attached to the
  structure and metal sheets attached to the
  Purlins.

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Common Structural Steel Materials

• Plates Flat pieces of steel of various
  thickness used at the intersection of different
  members.
• Bars Used as supports or braces for other steel
  parts or connectors
• Structural Shapes Available in several
  different manufactured shapes

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Structural Steel Callouts Structural steel
materials are specified by shape designation,
flange width, and weight in pounds per linear foot

• For Example W 24 x 120

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Structural Steel Shapes

• ST structural tees cut from S shapes
• MT structural tees cut from M shapes
• T structural tees
• Z zee shapes
• HP steel H piling

• W wide flange shapes
• S American Std. Beam
• M Misc. beam column shape
• C American Std. Channels
• MC Misc. channel shapes
• WT Structural tees cut from W shapes

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Shop Drawings

• Shop drawings are used to break each individual
  component of a structural engineering drawing
  down into fabrication parts
• Also referred to as Fabrication Drawings

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Common Connection Methods

• Bolting
• Nails
• Welding

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Components in a Set of Structural Drawings

• Floor Plan
• Foundation Plan and Details
• Concrete Slab Plan and Details
• Roof Framing Plan and Details
• Roof Drainage Plan
• Building Sections
• Exterior Elevations,Panel Plan, and Wall Details
• Drawing Revisions

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Demonstrate Laying out a Set of
Architectural/Structural Drawings