College - Author 1

College of Architecture and Environmental Design

Department - Author 1

Architectural Engineering Department

Degree Name - Author 1

BS in Architectural Engineering

College - Author 2

College of Architecture and Environmental Design

Department - Author 2

Architectural Engineering Department

Degree - Author 2

BS in Architectural Engineering

Date

6-2020

Primary Advisor

Kevin Dong, College of Architecture and Environmental Design, Architectural Engineering Department

Additional Advisors

Richard Emberley, College of Engineering, Mechanical Engineering Department

Abstract/Summary

Determining the extent of the contribution of exposed timber on compartment fire dynamics in open floor plans is a complex process. Designers traditionally used compartmentalization design methods which create spaces where flashover is likely, given the fuel load and ventilation conditions. However, due to the large geometric dimensions and spread of fuel, fires in open floor plans are more likely to remain as localized or traveling fires. As such, an understanding of not only ignition potential but also flame spread is critical to characterizing the contribution of exposed timber. An integral step in characterizing the potential contribution is through an analysis of the transient phase of burning of timber and the phenomena of self-extinction in this phase of burning. A series of material characterization experiments were conducted on Douglas Fir Larch samples to observe the behavior of timber in transient burning under a wide range of heat fluxes. For each experiment, the temperature gradient was recorded with thermocouples while the mass loss rate was measured using a load cell. The rate of conduction into the virgin timber, critical heat flux and the mass loss rate needed for sustained burning were all calculated to provide bounding limits to flame spread and self-extinction. These experiments showed that the transient mass loss rate is significantly higher than the average steady state in exposed wood and that there are nuances from latent heat of vaporization that notably affect the charring rates. This project begins to develop the effects that the transient state can have in burning wood and its charring rates. As a result, it was found that the mass loss rate during the transient state is significant and thus should be considered for the design of exposed timber. These studies should be further developed and tested to help refine charring rates during the transient state and with larger scale tests begin to be applied towards the structural engineering of exposed wood under a fire event.

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