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What Is A Portal Frame?

What Is A Portal Frame?

A portal frame is a type of structural frame commonly seen in warehouses, garages, barns and sheds – anywhere a large open space is required for minimal cost. They are one of the most popular structural applications for commercial and industrial buildings because of their superior strength and structural efficiency.

A portal frame will typically consist of:

  • 2 rafters (or beams)
  • 2 columns
  • 2 knee plates
  • 2 footing brackets
  • Apex plate

Depending on the engineering requirements of the building, a portal frame will be fastened together with nuts, bolts, tek screws or a combination of all three. 

Portal frames are usually made from steel and clad with products like Colorbond or Zincalume. They are fixed to either a concrete slab or concrete pad footings.

History Of Portal Frames

Portal frames were first developed during World War II, but they became widely popular in the 1960s. Today, they are used to create different kinds of enclosures, particularly wide-span ones such as warehouses, agricultural buildings, hangars, factories, as well as retail and storage facilities. In Australia, they are most often used as structural framing for steel sheds, both residential and commercial.


Advantages of Portal Frames

There are many advantages to using portal frames when building wide-span enclosures. Large spaces can be built and enclosed with the minimum amount of materials, a huge advantage for builders because it helps them minimise costs.

Advantages include:

  • Quick and easy to build
  • Cost-effective
  • Can be used for multiple purposes
  • Low maintenance
  • Aesthetically pleasing

Portal frames are lightweight and can easily be fabricated off-site. While they are a simple structure, buckling can be a problem if care isn’t taken in the design phase.

Steel Portal Frame Building Construction

Watch a steel portal frame being constructed below. The steel building is 12.92 m wide per 12 m (2×6 m) long and the columns are 5 m high.


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