W8x31 is a rolled structural beam with wide flanges that is used in construction and other applications.
Table of Contents
W8x31 Beam Size and Dimensions
The dimensions and specifications of this structural steel beam are below:
|Web Thickness||0.29 in|
|Flange Thickness||0.44 in|
|Area Moment of Inertia||108 in4|
|Elastic Section Modulus||27 in3|
The depth of W8x31 beams may vary by 1/8” above and below the nominal value.
The flange width may vary by 1/4” above nominal and 3/16” below nominal. Flanges may be out of square by as much as 5/16”.
The distance from the center of the web to the center of the profile may be no greater than 3/16”.
The radii of fillets and toes for W-beams are not specified. Instead, these dimensions are left up to individual manufacturers.
Wide flange beams are designated by their depth x weight. The W8x31 designation indicates that the beam weighs 31 pounds per foot. A 10-foot section of W8x31 would weigh 310 pounds and a 50-foot section of W8x31 would weigh 1,550 pounds.
W8x31 Conversion to Metric
The metric equivalent to W8x31 is W200x46.1. This metric beam has the following specifications:
|Web Thickness||7.2 mm|
|Flange Thickness||11 mm|
W8x31 Section Properties
W8x31 Area Moment of Inertia
The area moment of inertia (or second moment area) for a W8x31 beam about the x-axis (perpendicular to the flange) can be calculated from the equation below:
The area moment of inertia of the W8x31 profile about the x-axis is approximately 108 in4.
W8x31 Section Modulus
The elastic section modulus for a W8x31 beam about the X-axis is calculated from the following equation:
The elastic section modulus for the W8x31 profile about the X-axis is approximately 27 in3.
The properties of W8x31 beams are specified by ASTM A6 “Standard Specifications for Rolled Structural Steel Bars, Plates, Shapes and Sheet Piling”