Structural Fire Engineering

Structural engineers design buildings to take the forces created from the weight of objects, materials, people and snow. What if we allowed engineers to design a structure for the forces caused by fire and explosions? With the effects of climate change, designing structures to withstand fire loads will become more and more important.

You may think that they already do, however the Ontario Building Code and National Building Code currently do not have performance based or deemed-to-satisfy clauses when it comes to fires and structures. The buildings codes have what is called a prescribed building code, this means that they tell you the fire rating of various assemblies. For example a double layered drywall wall will have a 1 hour fire rating.

The problem with this approach is the fire scenario can vary depending on the fuel available and the ventilation. A garage fire with a jerry can of gasoline is a lot more severe than a couch fire.

Many other building codes allow engineers to design to a certain performance based on parameters such as fuel load, ventilation from window and door openings, and size of the room. This allows engineers to use their creativity that may not necessarily be solved by a prescribed fire wall which would lead to safer buildings during a fire.

Some leading building codes in performance based design come out of Japan and the European Union which are often used as a valid approach to performance based design for structural fire engineering. Performance based design is not as conservative as a prescribed building code which means it would allow for cost savings for the same level of fire protection.

Something else that may not be captured by a prescribed building code is heat flux through a window to adjacent buildings. This is often controlled by local government property line setbacks and may no necessarily protect adjacent structures from a large fire. The distance between structures should be a function of window size, fire load and ventilation.

Allowing a professional engineer to take into consideration a fire load on a structure will make buildings more safe. It also allows engineers to optimized design based on an expected fire load instead of a laboratory fire. This also contributes to the safety of the building through considerations of smoke management, egress routes and fire suppression.

Things are moving forward for engineers who practice fire protection engineering. Professional Engineers of Ontario (the governing body for all engineers of Ontario) have recently recognized fire protection engineering as valid for experience to become a licensed engineer.

Engineers have the tools, research and ability to design structures safely for fire loads – if there is a unique problem that the prescribed building code can’t solve then consulting a Professional Engineer with experience in structural fire engineering is the first step.

 

Reference: Fire engineering vs. prescribed fire protection, Jimmy Jonsson, https://ifpmag.mdmpublishing.com/fire-engineering-vs-prescribed-fire-protection/

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