Which of the following materials is commonly used for making structural beams?

The most common material used for making structural beams is steel. Steel is favored in construction due to its high strength-to-weight ratio, durability, and versatility. Its ability to withstand heavy loads and resist bending makes it ideal for a variety of applications in building structures, bridges, and industrial facilities.

Steel beams are also resistant to environmental factors such as rot and pests, which can be significant issues when using wood or other organic materials. The flexibility of steel in design allows for long spans with fewer support columns, contributing to open floor plans and more aesthetic architectural designs.

While concrete is also a viable option for structural beams, especially in heavy construction, it typically requires reinforcement (such as steel rebar) to enhance its tensile strength. Oriented strand board is primarily used in wall sheathing, flooring, and as structural panels but is not common for heavy structural support. Plastic is generally not used for structural beams due to its lower strength compared to metal or concrete.