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Is Structural Steel Fire-Rated?

Structural steel is renowned for its strength and versatility in construction, but can it withstand an intense fire? Understanding the fire rating of structural steel is vital in ensuring the safety and resilience of buildings and infrastructures.

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Fire safety is a paramount concern in any building, and when it comes to the structural material used, one question that often arises is whether structural steel is fire-rated? 

Find out about structural steel and its fire ratings below

We all know that steel is renowned for its strength and durability, but what about its ability to withstand the intense heat of one of nature’s most formidable forces?

In this article, we will delve into the fascinating world of structural steel and explore whether it has what it takes to stand up to the fiery challenges it may face. Grab your hard hat, and let’s dive in. Be warned, it’s going to get hot!

What is a fire rating?

Before we dive into the specifics, let’s start with some basics. 

Fire ratings measure how well a material can withstand fire and prevent its spread. It’s like a report card for fire safety, telling us how long a material can resist the destructive forces of flames and heat.

The fire rating is expressed in minutes and represents the time it takes – for structural steel in this instance – to reach a specific temperature or structural failure point. Globally, a common fire rating for structural steel is one to two hours, which means it can withstand fire for that duration before losing its strength.

Structural steel is innately fire-resistant and noncombustible

There are many reasons why structural steel is widely used in residential, commercial and industrial buildings and other structures. One of these reasons is its ability to withstand fire. 

Structural steel – and components like beams, plates, girders and columns  – boasts innate fire-resistant characteristics that set it apart from other construction materials. Unlike wood or certain alloys, steel doesn’t combust or contribute to the spread of flames. 

Even when exposed to high temperatures, steel retains its strength and load-bearing capacity, supporting a building’s structure during a fire. This inherent fire resistance of steel ensures that it remains structurally sound, allowing occupants valuable time for evacuation and firefighters an opportunity to combat the blaze effectively.

Structural steel is innately fire-resistant and noncombustible

Testing the fire resistance of structural steel

Structural steel undergoes significant testing to both Australian and international standards to determine its fire resistance.

This testing subjects structural steel components to controlled, real-life fire conditions while extensive monitoring occurs. 

Aspects such as temperature rise, deflection, and load-bearing capacity over specified durations are evaluated. This provides a highly valuable insight into how steel behaves under fire and aids in assigning fire ratings.

Boosting the fire resistance of structural steel

While it can withstand fire and high temperatures, structural steel isn’t fireproof. 

Typically, at temperatures above 550°C, structural steel’s load-bearing capacity can be affected. At higher temperatures or with long exposures to this higher heat, it will eventually lose its strength and buckle, ultimately causing collapse.

With building fires sometimes exceeding 800°C, more can be done to increase the fire resistance of structural steel:

  • Thicker steel sections tend to be more fire-resistant as they dissipate heat more slowly. 
  • The shape of the section can also impact its fire rating. For example, a circular hollow section might have a higher fire rating than an equivalent square or rectangular section due to its enhanced thermal properties.
  • Implementing proper engineering and construction methods, such as employing fire-resistant barriers or compartmentalisation, significantly influences the steel’s performance in fire situations.
  • Applying fireproof coatings or fire-retardant treatments can further increase structural steel’s fire protection. Essentially, these act as a barrier against heat transfer, insulating the steel and extending the duration before the steel faces a fire’s direct impact. 

Raising the standards

While there is no specific Australian Standard for structural steel design and fire, several are relevant. These guidelines are integrated within the primary steel-related Design Standards, which include:

  • AS 4100 Steel structures
  • AS/NZS 5100.6 Bridge Design – Part 6: Steel and composite construction
  • AS/NZS 2327 Composite structures – Composite steel-concrete construction in buildings
  • AS/NZS 4600 – Cold-formed steel structures
Raising the standards

Striving to be the best

You can’t be a great company if you don’t take quality, safety and environmental performance seriously, which is why they are at the core of everything we do.

This includes ensuring the structural steel and fabrication projects we complete meet strict fire rating standards and guidelines. 

The fire rating of structural steel stands as a critical consideration in construction and building safety. While structural steel is inherently fire-resistant, at every stage of our processes, we ensure the safety, resilience, and longevity of fabrication products we produce will remain robust even in the face of fire emergencies.

Will structural steel produced today still be around in 100 years

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