A pre-engineered steel building is a modern technology where the complete designing is done at the factory and the building components are brought to the site and then fixed/jointed at the site and raised with the help of cranes. An efficiently designed pre-engineered building can be lighter than conventional steel buildings by up to 30%. Lighter weight equates to less steel and potential price savings in the structural framework. Prefabricated buildings are advantageous because they very economically allow for the creation of large column-free enclosures.
PEB structures consist of various components that give them their unique properties and make them sturdy and durable. It is through the combination of various small and large parts that a PEB is made strong, durable, and flexible. Like any assembled structure, these elements form the basic steel framework. The components of PEB structures are divided into three main types and a few accessories.
A pre-engineered steel building is a portal frame construction that comprises primary and secondary framing and bracing systems. As a result of these three elements and the weather resistant sheeting, steel buildings are more stable than individual steel frames.
Primary components of the PEB consist of the mainframe, column, and rafters.
The main frame is the building’s primary construction, which is built of flexible steel. Tapered columns and rafters, which are sometimes referred to as built-up members, are used to construct the structure. Spliced plates are welded to the ends of these tapering pieces. The connecting section splice plates are bolted together, and the frame is assembled.
Columns: The vertical load is transferred to the foundations via columns. As they are made of I sections, they are strong and economical to produce. A column’s width and breadth will increase from bottom to top.
Rafters: Rafters are tilted structural components or beams that go from the ridge to the wall plate. They are meant to support the roof deck and any corresponding weight.
The secondary framing system consists mostly of purlin and girt of varying diameters of Z or C forms. Cold form Z sections are often used for secondary framing in pre-engineered structures to ensure high strength and low weight. Purlins and girts are members that further strengthen the attachment of one frame to another so that a building’s structure remains stable. This serves as a framework for weather covering sheets.
Purlins are used on the roof; girts are used on the walls; and eave struts are used where the sidewall meets the roof. It is required that purlins and girts be cold-formed “Z” sections with stiffened flanges.
Eave struts must be cold-formed “C” sections with uneven flanges. Eave struts are 200 mm deep and have a 104 mm wide top flange and a 118 mm wide bottom flange, both of which are parallel to the roof slope. Each flange has a stiffener lip of 24 mm.
Cable bracing is a major part that protects the building’s stability against lateral forces such as wind, and earthquakes. Diagonal bracing must be incorporated in the roof and side walls.
Roofing or Cladding
Roofing sheets protect the interior of a building from the elements. Based on the requirement, these can either block sunlight or let partial sunlight illuminate the interiors. Pre-engineered buildings are constructed from base metals of either Galvalume coated steel conforming to ASTM A 792 M grade 345B or aluminium conforming to ASTM B 209M, which is cold-rolled steel, high tensile 550 MPA yield stress.
Several accessories are available that are not only structurally vital, but extremely useful and can considerably increase the building’s efficiency. The accessories can be chosen based on the type of application. Non-structural components in pre-engineered steel constructions include bolts, turbo ventilators, skylights, louvres, doors and windows, roof curbs, and fasteners.
A PEB can better meet the need for flexible separation between wide openings in buildings than a traditional structure by reducing the cross-sectional size of columns and using lightweight wall panels. The effective indoor usage area gets increased by around 6%. With a steel structure, mass production in factories is possible and advanced products can be integrated into one application, such as energy-saving products, waterproofing, heat insulation, doors, and windows. As a result, construction standards can improve.