Passive fire protection of steel structures
Structural steel, by definition, is a steel structure that is helping to hold up a building.
The steel structure might consist of vertical columns and horizontal beams, along with some bracing. The beams might be supporting a composite concrete slab.
In a building fire, temperatures can quickly rise within a compartment space to 500˚ C and, without sprinkler intervention, the temperature can continue to rise significantly, as long of course as there remains sufficient fuel and oxygen to allow sustained combustion.
Without adequate passive fire protection applied to these steel structures, at these elevated temperatures the steel loses strength and starts to bend and, in extreme cases, can result in the collapse of part of or all the building.
Passive fire protection isn’t hard to understand. You apply material over the steel, to provide insulation to keep the steel below the temperature where it can start to lose strength.
Whilst the concept is simple, the application is far from that and requires considerable experience and a comprehensive understanding of the subject.
The attached article delves much more deeply into the matter, providing a valuable insisght into the intricacies and requirements of passive fire protection of steel.
Below are some dot-point conclusions but we recommend that you download and read the full article.
- NCC requires strict use of AS4100 and 7 coefficient linear regression for determination of FRLs
- Fire testing must include full scale load bearing elements
- All fire test assessment reports must include the seven coefficients, k0, k1…k7
- Don’t be fooled by the big name suppliers; ask for their fire test assessment report and double-check compliance yourself
- The fire test assessment report should be readily available on the product supplier's website
- Fire test laboratories are culpable in part for some confusion in the market by way of writing assessments that do not include the NCC requirements for AS4100 and the seven coefficient linear regression analyses mandatory requirement
- If it says in the assessment report it may, instead of it does, be concerned as you might not be installing compliant steel passive protection systems under the so-called "Deemed to Satisfy Provisions"
- If in doubt ask... the staff at Trafalgar are happy to review reports and point you in the right direction
- You can trust Trafalgar; we believe safety should never be taken for granted
More articles
Passive fire protection and the importance of limiting temperature for steel structure
All materials become weaker when they get hot and structural steel is not an exception. Depending on the design of the structure, the steel will have a limiting or critical temperature.
What does this mean, and why is it important? How does it affect the amount of protection needed?
Fire protection of concrete-filled, hollow structural steel
Filling of closed profile or structural hollow sections with concrete is a well-known practice in the structural design of buildings.
It offers several advantages over unfilled hollow sections, such as cost versus strength optimisation, durability and aesthetics, increased fire resistance and much more, but it needs to be done correctly.
The importance of getting it right
KTA-Tator are a North American company specialising in the testing of steel and concrete structures. With over 70 years' experience they have amassed a sizable body of knowledge, making them one of the leaders in third-party testing in the USA.
One of their consultants, Jay Helsel, recently posted a case study, reporting on the findings of their investigations into the failure of intumescent coatings applied to a project in a north-eastern, coastal location in continental USA.
Fire stopping of service penetrations
There are many means through which heat can move from the fire side of a barrier to the non-fire side of a barrier. The fire barrier and/or the fire stopping material(s) themselves can (and do) get hot on the non-fire side in a fire, so choice and construction of fire barriers are important and differ depending on the fire rating duration.
This article assists in making those choices.
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