Survival of Burnout with Exposed Mass Timber
For cases where the structure is intended to survive burnout, if timber structural elements are left exposed (ie unprotected), then it is acceptable for the structural timber to ignite; nevertheless it should be explicitly demonstrated that the structural timber will extinguish (flaming combustion) after the consumption of the moveable fuel load and other internal linings. Given the natural performance uncertainties introduced by the timber products, explicit conservativeness will need to be included in the assessment of the conditions that lead to extinguishment of exposed structural timber.
Within the process of qualifying principle 6, the following two would apply:
8
– Define a threshold for extinguishment of flaming combustion. – Carry out analysis to evaluate if the threshold is met.
Sensitivity/Consequence Analysis
– Identify variables and their uncertainty. – Evaluate consequences through the identified range of uncertainty. – Identify credible scenarios requiring failure analysis. – Carry out the associated failure analysis.
A sensitivity/consequence analysis that focuses on damage potential should be conducted for reasonably foreseeable failure modes, and the impacts of a fire on the timber structure, on all surrounding buildings and on fire brigade interventions.
9
Smouldering Combustion
Smouldering combustion is a secondary hazard that, if allowed to develop and left unattended, can challenge the integrity of the structure. The fire safety strategy for a building should explicitly acknowledge this hazard noting that the fire brigade will have a role in ensuring smouldering is addressed. These fire brigade activities should be aligned to conventional practices for more traditional forms of construction.
– Provide explicit communication to the fire brigade, articulating smouldering risk and consequences as situations that the fire brigade will encounter in a building with mass timber structures.
10
74
F I R E
Made with FlippingBook - professional solution for displaying marketing and sales documents online