

Standard sizes of I-beams
I-beams, also known as H-beams, are characterized by their cross-sectional shape. Their dimensions and properties are standardized for consistency and reliability in structural applications. I-beams efficiently resist bending and shear loads, making them ideal for various structural applications such as building frames, bridges, platforms, and crane rails.

Designation and dimensions
I-beams are designated by the letter “S” followed by the nominal depth in inches and the weight in pounds per foot. For example, an I-beam labeled as S12x50 indicates:
- Depth: 12 inches
- Weight: 50 pounds per foot
Common standard sizes
The following table summarizes some common standard I-beam sizes:
Designation | Depth (inches) | Weight (lbs/ft) | Flange Width (inches) | Web Thickness (inches) |
S3x5.7 | 3 | 5.7 | 2.33 | 0.17 |
S4x7.7 | 4 | 7.7 | 3.00 | 0.20 |
S6x12.5 | 6 | 12.5 | 4.00 | 0.25 |
S8x15 | 8 | 15.0 | 5.00 | 0.25 |
S12x50 | 12 | 50.0 | 8.00 | 0.50 |
S24x121 | 24 | 121.0 | 12.00 | 0.75 |
Variations
I-beams can also be categorized into standard and light varieties. Light I-beams have smaller thicknesses and lighter weights. The flange width varies with the model size, where smaller models have narrower flange widths.
Standards and regulations
The dimensions and properties of I-beams are regulated by various standards, including:
- ASTM A992: Standard specification for structural steel shapes.
- ASTM A36: Standard specification for carbon structural steel.
- EN 10025: European standard for hot-rolled structural steel.

Considerations
When selecting an I-beam for a project, it is essential to consider factors such as:
- Load-bearing capacity: The weight the beam must support.
- Span length: The distance between supports.
- Material properties: The type of steel and its characteristics.
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