I-beams are primarily measured and specified based on their depth and weight per unit length.
Standard Specification Method
In the United States, steel I-beams are commonly specified using these two key properties: their overall depth and their weight per foot. The depth refers to the nominal height of the I-beam, measured from the outer face of one flange to the outer face of the other flange. The weight is typically given in pounds per foot (lb/ft).
Understanding the Notation (e.g., W10x22)
A common method of specifying I-beams uses a code like "W10x22". This notation indicates:
- "W": Denotes a wide-flange beam section. Other letters exist for different shapes.
- "10": Represents the approximate depth of the beam in inches (in this case, approximately 10 inches). As mentioned, this is the nominal height from flange to flange.
- "22": Indicates the nominal weight of the beam per foot in pounds (in this case, 22 lb/ft).
So, a "W10x22" beam is roughly 10 inches deep and weighs 22 pounds for every foot of its length. This system allows engineers and builders to quickly understand the key physical properties and structural capacity of the beam for design and ordering purposes.
