IIE Lunchtime Seminar - Alastair Bartlett (University of Edinburgh)

Cross-laminated timber: designing for burnout

Abstract:

Engineered timber products are becoming increasingly popular in the construction industry due to their attractive aesthetic and sustainability credentials. Structural timber elements such as cross-laminated timber (CLT) wall or floor panels may act as an additional fuel load, and this risk must be adequately quantified to satisfy the intent of the building regulations that the structure does not continue burning after the burn out of the movable fuel load. A series of bench-scale flammability studies were undertaken in the Fire Propagation Apparatus (FPA) to explore the conditions under which auto-extinction will occur at a material scale. Critical conditions were determined experimentally, and a methodology based on firepoint theory was proposed to predict this phenomenon as a function of applied external heat flux and quantification of the heat losses. Subsequently, full-scale compartment fire experiments with exposed timber surfaces were performed to determine if auto-extinction could be achieved in real fire scenarios. It was demonstrated that auto-extinction could be achieved in a compartment fire scenario, but only if significant delamination of the engineered timber product did not occur.  A modified version of the bench-scale methodology for predicting auto extinction was successfully shown to predict auto-extinction when delamination did not occur. A supplementary series of reduced-scale compartment fire experiments demonstrated that auto-extinction can be achieved if burnout of the compartment fuel load is achieved before significant delamination of the outer lamella takes place. With further research, application of this methodology will enable compartments with exposed CLT elements to be designed for burnout.

Bio:

Alastair Bartlett is a final year PhD student at the University of Edinburgh. He received an MEng in Civil Engineering in 2014 from the University of Edinburgh, with a thesis exploring charring rates of CLT under non-standard heating scenarios. His research focuses on the changes in fire dynamics associated with exposed timber elements.