Steel is one of the most vital building materials used in the construction industry today, known for its strength, versatility, and durability. It is used in a variety of forms to suit different construction needs, and rolled steel sections are among the most commonly employed types of steel products. These sections are produced through continuous casting in molds, creating long, solid forms without any joints. Understanding the different shapes, sizes, and properties of these rolled steel sections is essential for their proper application in construction projects. This article explores the various types of rolled steel sections, their properties, and their uses in construction.
Different Forms of Rolled Steel Sections
Rolled steel sections come in a wide range of forms, each designed for specific applications. The key types of rolled steel sections include:
- Angle Sections
- Channel Sections
- T-Sections
- I-Sections
- Round Bars
- Square Bars
- Flat Bars
- Corrugated Sheets
- Expanded Metal
- Plates
- Ribbed Bars (HYSD)
- Ribbed Bars (Mild Steel)
- Thermo-Mechanically Treated (TMT) Bars
- Welded Wire Fabrics
Each of these forms has unique characteristics that make them suitable for specific uses in construction.
Detailed Explanation of Rolled Steel Sections
1. Angle Sections
Angle sections are shaped like the letter “L” and consist of two legs that meet at a right angle. These sections are available in two forms:
- Equal Angle Sections: Both legs are of the same size.
- Unequal Angle Sections: The legs are of different sizes.
These sections are widely used in the construction of roof trusses and filler joist floors. The size range for angle sections spans from 20mm x 20mm x 3mm to 200mm x 200mm x 25mm, with corresponding weights varying from 9 N to 736 N per meter.
2. Channel Sections
Channel sections are shaped like the letter “C”, with two equal flanges connected to a central web. These sections are frequently used in steel-framed structures due to their ability to bear loads effectively. The size range for channel sections spans from 100mm x 45mm to 400mm x 100mm, with corresponding weights ranging from 58 N to 494 N per meter.
3. T-Sections
T-sections are shaped like the letter “T”, consisting of a flange and a web. These sections are used in steel roof trusses and can also be formed by joining two angle sections. T-sections are available in sizes ranging from 20mm x 20mm x 3mm to 150mm x 150mm x 10mm, with weights ranging from 9 N to 228 N per meter.
4. I-Sections
I-sections, also known as steel beams or rolled steel joists, are extensively used in construction as beams, lintels, and columns. These sections are characterized by two horizontal flanges connected by a vertical web. I-sections are available in a wide range of sizes, from 75mm x 50mm to 600mm x 210mm, with weights varying from 61 N to 995 N per meter.
5. Round Bars
Round bars feature a circular cross-section and are typically used as reinforcement in concrete or in the construction of steel grill works. They are available in diameters ranging from 5mm to 250mm. These bars provide excellent flexibility and strength when used in various structural applications.
6. Square Bars
Square bars have a square cross-section and are commonly used in applications like gates, windows, and grill works. The sides of square bars can range from 5mm to 250mm, providing versatility for a range of uses in construction.
7. Flat Bars
Flat bars are rectangular steel sections used for structural applications such as gates, windows, and grill works. These bars are characterized by their flat surface and are available in a wide range of widths (from 10mm to 400mm) and thicknesses (from 3mm to 40mm).
8. Corrugated Sheets
Corrugated sheets are made by pressing plain steel sheets through machines to create bends or corrugations. These sheets are primarily used for roof coverings, offering durability and resistance to external elements. The corrugated design enhances their strength and ability to distribute loads across the surface.
9. Expanded Metal
Expanded metal sheets are made by cutting and stretching mild steel sheets, creating a distinctive diamond-shaped mesh pattern. These sheets are commonly used for applications such as fencing, security panels, or grating due to their high strength-to-weight ratio and flexibility.
10. Steel Plates
Steel plates are thick, flat sections of steel that are commonly used for structural connections, such as in the connection of steel beams or as tensile members in roof trusses. Steel plates are available in a range of thicknesses from 5mm to 50mm.
11. Ribbed Bars (HYSD)
High Yield Strength Deformed (HYSD) bars are steel bars that have been twisted to form projections (or ribs) along their surface. These ribs improve the bonding between the steel and the surrounding concrete, making them ideal for reinforcement in concrete works, such as in bridges, buildings, and foundations. HYSD bars range in size from 6mm to 50mm in diameter and offer several advantages, including high strength, excellent bendability (up to 180°), and reduced cost compared to other types of bars.
12. Ribbed Bars (Mild Steel)
Ribbed bars made from mild steel resemble HYSD bars but have much lower strength and are less commonly used in modern construction. They are not recommended by building codes for structural reinforcement.
13. Thermo-Mechanically Treated (TMT) Bars
TMT bars are produced by quenching hot steel bars to rapidly cool the outer surface while allowing the core to remain hot. This process strengthens the outer surface, making the bar highly resistant to corrosion and increasing its yield strength. TMT bars are widely used in reinforced concrete structures due to their high durability and elongation properties. The addition of elements like copper and phosphorus further enhances their corrosion resistance.
14. Welded Wire Fabrics
Welded wire fabrics are composed of a series of mild steel bars arranged perpendicular to one another and welded at their intersections. These fabrics are primarily used as reinforcement for floor slabs, pavements, and small canal linings. They provide an efficient and cost-effective solution for reinforcing concrete surfaces.
Conclusion
Rolled steel sections are fundamental components in modern construction, offering strength, durability, and versatility. From the wide array of shapes, sizes, and types—including angle sections, I-sections, T-sections, and specialized products like ribbed HYSD and TMT bars—each section plays a specific role in ensuring the stability and reliability of structures. Understanding these different forms of rolled steel helps engineers, architects, and builders select the right materials for their construction projects, optimizing both cost and performance. Whether for structural reinforcement, framing, or roofing, rolled steel sections remain indispensable in the building industry.