The role of hot rolled steel in pre-engineered buildings

In steel structure design, adopting the pre-engineered building (PEB) system marks a significant advancement, offering cost-efficiency, environmental benefits, and sustainability. Previously, the construction of steel structures largely relied on the conventional steel building (CSB) approach, which was both time-intensive and costlier. The higher expense associated with CSB stemmed from the extensive use of uniform hot-rolled sections across each structural member. In contrast, PEB systems utilise built-up sections tailored to specific loading effects, employing bolted connections on-site for easy assembly. This method accelerates the construction timeline and results in a lighter design, making it especially suitable for projects requiring large spans and open spaces without columns. Structure member design and fabrication are completed in a plant setting and then transported to the construction site for erection, streamlining the overall building process.

Hot-rolled steel is a crucial component in the construction of PEBs. This material plays a significant role in ensuring the strength and durability of these structures. Let's explore the importance of hot-rolled steel in PEBs.

What is hot rolled steel?

Hot-rolled steel is produced by rolling steel at high temperatures, typically over 1700°f. This process makes the steel easier to shape and form, making it more workable and suitable for various applications. Hot-rolled steel is available in different forms, such as coils, sheets, and sections.

Key benefits of hot rolled steel in PEBs

Strength and durability: hot-rolled steel is known for its high strength, making it ideal for structural applications in PEBs. It provides the necessary support and stability for the building.

Versatility: this type of steel can be easily shaped into various forms, including beams, columns, and frames. This versatility makes it suitable for different parts of the building structure.

Cost-effectiveness: hot-rolled steel is generally more affordable than other steel types. This cost advantage makes it a preferred choice for large-scale construction projects like PEBs.

Availability: hot rolled steel is widely available, ensuring a steady supply for construction projects. This availability helps in meeting tight construction timelines.

Key elements of pre-engineered buildings (PEBs)

Pre-engineered buildings (PEBs) can be broadly categorised into two principal segments:

• Primary members: these constitute the core framing components, columns and rafters. Manufactured through hot-rolling, they typically feature a tapered profile.

• Columns: crafted from hot-rolled sections, these structural elements boast a minimum yield strength of 345 n/mm². They are mostly designed as I section with welded flange and web plates.

• Rafters: acting as horizontal supports for roof sheets and purlins, rafters have a similar construction to columns. Still, their dimensions might vary to suit specific designs.

• Secondary members: this group includes purlins and girts, essential for the roofing system. These members are usually made through cold-forming processes, providing a high strength-to-weight ratio.

• Purlins: positioned transversely across the rafters, purlins are typically formed into z or c shapes from cold-formed steel sections with a minimum yield strength of 340 n/mm².

• Girts: functionally akin to purlins, girts run along the building's columns and possess similar characteristics.

Other integral components of PEBs encompass sheeting materials, trims, gutters, and various fittings. Sheeting and additional elements are predominantly produced via cold-forming, resulting in lightweight and thin products.

Additional PEB components

Roofing and sheeting: these metal sheets, used for roofing and wall cladding, are made from 0.5 mm cold-rolled steel coated in an aluminium/zinc mix.

Trims and gutters: pre-formed from lightweight gauge metal trims are devised to conceal exposed steel edges, whereas gutters are designed to manage and direct rainwater from the roof.

Applications of hot rolled steel in PEBs

Structural frames: hot-rolled steel sections are used to create the primary structural frame of PEBs. These frames provide the skeleton of the building, supporting the roof and walls.

Roofing and cladding: hot-rolled steel sheets are often used for roofing and wall cladding. They offer protection against weather elements and add to the building's strength.

Flooring systems: steel plates made from hot rolled steel are used in flooring systems, providing a sturdy base that can withstand heavy loads.