Meta-analysis of temperature, heat release rate, delamination and auto-extinction of timber compartments

A meta-analysis was conducted on 100 structural mass timber compartment fire experiments. The analysis investigated temperature, heat release rate, auto-extinction and delamination. Dissimilarities in the compartment geometry, ventilation, and exposed timber surfaces of these experiments could be accounted for using two parameters, α and %A_O (applicable to near cubic, ventilation-controlled compartments) defined as the shape-modified ventilation factor and opening ratio. The correlation coefficient for the total heat release rate (HRR) with the area of timber for the large and medium scale data was 0.97 and 0.74, respectively. Similarly, the correlation of medium scale data for the contribution of timber to the heat release rate was 0.90. A statistical analysis revealed a higher probability for auto-extinction to occur for exposure levels below 20%. Above 20% exposure, the risk for sustained flaming and delamination increase substantially. Auto-extinction was shown to depend strongly on delamination, with a 93% probability of occurrence given no delamination. The use of PUR HBS adhesive was shown to cause delamination in 73% of the cases, with PUR HBX delaminating in 33% of cases.