An I-beam, also known as an H-beam, W-beam, or universal beam (UB), is a common type of steel beam used in Australian commercial construction projects. It is characterized by its cross-sectional shape, which resembles the letter "I" or "H" with a wide, flat flange on either side of a narrow web.

The I-beam's design provides a high strength-to-weight ratio, making it suitable for various applications in construction. The wide flanges provide a large area for bearing loads, while the narrow web offers resistance to bending and shear forces.

In Australian commercial construction projects, I-beams are commonly used for structural framing, including columns, beams, and girders. They are used to support floors, roofs, and other structural elements. I-beams can be made from various materials, but steel is the most common due to its strength, durability, and ease of fabrication.

The dimensions and specifications of I-beams used in Australian construction projects are typically determined by the Australian Standards, such as AS/NZS 3679.1, which provides guidelines for the design and manufacture of steel structural elements. These standards ensure that the I-beams used in construction projects meet the required strength and safety criteria.