Steel Construction Manual

American Institute of Steel Construction

Thirteenth EditionPart 1

Dimensions and Properties

Wide-flange (W) ShapesMost widely used section

Essentially parallel inner and outer flange surfaces

Two flanges held apart by a web

W 24 x 55

Section designation

Nominal depth in full inches

Weight in pounds/per foot

Nominal depths from 4-inch to 44 inch

Weights available from 9 lb/ft to 800 lb/ft

Wide-flange (W) Shapes

5

W 14 x 730

Actual depth is 22.4 inches

All shapes from W14 x 90 to W 14 x 730 have flat (T) part of web of 10 inches.

All these shapes can be stacked on each other

W 14 x 90

Actual depth is 14 inches

Flange

Web

Major axis

Designation

Weak axis

Cross-sectional area

Actual depth

WebThickness

Flange Properties

Spacing between rowsof bolts in flange

Flat portion of web

End of fillet transition between

web and flange

Weight per foot

Moment of Inertia (I), elastic section modulus (S), radius of gyration (r), plastic section modulus (Z) for strong and

weak axes

Flange and web stabilityparameters

M-Shapes

Not classified in ASTM 6 as W-, S- or HP- shapes

Same properties (A, d, tw, bf, etc) as W- shapes

Can have sloped inside flange or other features

American Standard (S) Shapes16-2/3% slope on inner flange surface

S24x121

Section designation

Nominal depth

Weight per foot

Relatively narrow flanges and thicker webs when compared to W shapes

Use is less common because of lower moment of inertia, tapered flanges and low lateral stiffness

Narrow flange

Note: slope on inside of flange

Same properties as for W shapes

Channels

C15x50

Section designation

Actual depth

Weight in pounds per foot

MC – Miscellaneous channel – Other than 2 on 12 slope on inner flange

Nominal depth is same as actual depth

Actual depth

Property for design

Property fordetailing

L6x4x3/4

Short leg length

For a single angle major axes do not correspond to x and y axes

Long leg length

Thickness of both legs

Angles

Section designation

Equal leg and unequal leg angles available

Angles are best used in pairs as LLBB (Long-leg-back-to-back) or SLBB (Short-leg-back-to-back).

Designation

Location of elastic centroid

Location of plastic centroid X axis properties

Y axis properties

Minor (weak) axis for a single angle

TeesWT -, MT- and ST- are obtained by shearing or thermal-cut from parent shape of W, M and S respectively

Two WT 22 x 131 can be made by cutting a W 44 x 262

Off-center cuts can be done but properties not listed in Manual

Used for top and bottom chords of trusses and diagonal bracing in buildings

Nominal depths and weights of a WT is exactly half of the parent shape

Stem, not web

Hollow Structural ShapesRectangular, Square or Round HSS

Welded or Seamless

Welded HSS made by welding sheet steel

Seamless made by extrusion of solid round bars

HSS 10 x 4 x 3/8 Wall thickness

Section Designation

Outside longer dimension

Outside shorter dimension

Outside LongerDimension

Outside ShorterDimension

Actual Wall Thickness

Design Wall Thickness = 0.93 x Actual Wall Thickness

Strong axis structural properties

Weak axis structural properties

Equal outside dimensionsStructural properties for strong and weak axes

Diameter over design thickness

Nominal versus design thickness

Standard, x-strong and xx-strong designations

Nominal wall thickness

Double Angles

2L6x4x3/4

Major axes are now x and y

X axis properties may be obtained from x axisproperties of single angle

Y axis properties depend on separation between backs angles and whether LLBB or SLBB

Long legs back-to-backShort legs back-to-back

Separation due to gusset plates

Radius of gyration for compression members

Double Channels

Designated as 2C or 2MC

2C15x50

Y axis properties depend on back-to-back separation

X axis properties can be obtained from x axisproperties of single channel

Y axis properties depend on back-to-back distance (gusset plate thicknesses) between individual channels

Channel

W shape Weight

Moment of Inertia, Ixx

Suitable for Crane Girders

Nominal wall thickness

Limited availability

Steel Types

Preferred Specification

Plates > 8 inch widthBars < 8 inch width

Thickness in inches