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

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

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

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)

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.

Example of How Drawing Elements Are Coordinated Between Pages

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.

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

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

Examples of Standard Structural Callouts for Concrete Reinforcing

• Specifying Rebar #4@12”O.C.

(25)#8k@24”O.C.

HORIZ. AND 16” O.C.

VERT #6@24”O.C.EA

WAY (or EW)

• Specifying Anchor Bolts– (12)-3/4”ØX12”STD AB

24” OC W/3”PROJ

Types of Concrete Construction

• Poured-in-place concrete

• Pre-cast Concrete

• Tilt-up Pre-cast Concrete

• Concrete Block Construction

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

Wood Construction• Used in both residential and commercial

applications

• Commercial applications include:– Partition Framing

– Upper-level Floor Framing

– Roof Framing

Types of Wood Construction

• Heavy Timber Construction

• Laminated Beam Construction

Note: The drafter’s major responsibility is the drawing of the connection details for Heavy Timber Construction and Laminated Beams

Engineered Wood Products

• I-Joists

• Laminated Veneer Lumber

• Rim Board

• Plywood Lumber Beams

• Stressed Skin Panels

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

Steel Construction

Three Categories:– Steel Studs

– Prefabricated Steel Structures

– Steel-framed Structures

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.

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

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

Structural Steel Shapes• 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

• ST – structural tees cut from S shapes

• MT – structural tees cut from M shapes

• T – structural tees• Z – zee shapes• HP – steel H piling

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”

Common Connection Methods

• Bolting

• Nails

• Welding

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

Demonstrate Laying out a Set of Architectural/Structural

Drawings