NEW SCIENCE
FIRE SAFETY ARTICLE
BASEMENT FIRE COMPUTER MODELING WINTER 2014 UL.COM/NEWSCIENCE
NEW SCIENCE
FIRE SAFETY OVERVIEW
UL’s dedicated team of scientists, engineers and researchers is creating New Science in a variety of ways. From live experiments to computational modeling, statistical analysis to quantification of risk, we are constantly seeking to improve products, techniques, methodologies, processes and standards.
FIRE SAFETY ARTICLE/BASEMENT FIRE COMPUTER MODELING
2
WHY BASEMENT FIRE MODELING MATTERS Basement fires are an extremely dangerous challenge for firefighters. In the late 1970s, fire deaths inside a structure occurred at a rate of 1.8 deaths per 100,000 structure fires. By the late 1990s, the mortality rate had risen to three per 100,000.1 Fire Engineering notes that a “large majority of firefighter fatalities or significant injuries occur at what were ultimately basement fires.”2 For these reasons, it is critical to understand the particular safety risks associated with basement fires through experimentation and advanced engineering analysis. To build on and further the knowledge gained from physical experiments, UL relies on computational fluid dynamics (CFD)-based fire modeling tools to expand the available experimental dataset and deepen insights.3
CONTEXT Today, the combination of larger homes, open floor plans, synthetic fuel loads and new construction materials speed up the stages of fire development, creating more hazardous fire conditions.4 One important contributor to the increased fire safety risks – meriting close examination – is engineered wood products, which are increasingly used to help meet the demand for environmentally sustainable and economical building products. Under fire conditions, lightweight engineered floors can lead to greater risk of structural failure in a shorter time period as a result of the reduced cross-sectional dimensions of engineered products relative to traditional lumber floors. When there is a basement fire, or a fire that started in the basement, once on the scene, the fire service is often unclear regarding how long the fire has been burning, the type of floor system exposed to fire conditions and the structural stability of the floor system.
As the use of engineered wood products has increased to help meet the demand for environmentally sustainable and economical building products, fire safety risks are increasing.
In our previous “New Dynamics of Basement Fires” article, we detailed the results and insights from a variety of research experiments UL conducted to better understand the response of residential flooring systems to fire.5 In addition to those research experiments, we generated both thermo-mechanical finite element models to simulate the structural response 6 and CFD-based fire models to simulate the fire dynamics and effects of different ventilation schemes. In this article, we describe the effects of different ventilation schemes on basement fire dynamics through our fire modeling work.
WHAT DID UL DO? Using data from live experiments of a basement fire with an engineered wood I-beam ceiling, we built a CFD-based fire model of the same experiment, using
FIRE SAFETY ARTICLE/BASEMENT FIRE COMPUTER MODELING
3
Fire Dynamics Simulator software, and compared the results. The model for a fully ventilated condition generally replicated data from the experiment, providing first-order validation. As the fire dynamics depend strongly upon ventilation conditions, we ran several different models, rather than conducting more expensive large-scale fire experiments, to determine this sensitivity. The other models included changing the ventilation conditions by opening or closing a door or window at different points in time. The choice of scenarios aimed to help examine the quality of the model predictions over a range of ventilation regimes, from fully ventilated to under-ventilated. Based on modeling the different scenarios, we found that: • For the Fully Ventilated Basement scenario, where all doors and windows were open for the entirety of the simulation, model predictions compared quite well with experimental data. As compared to an experiment, where data is only available at a few discrete points, the model of the basement fire generated temperatures (gas and thermocouple), airflow, smoke movement and other variables over the entire domain of the basement. This allowed for greater insight into the dynamics of the fire. The model captured some of the key features, such as the movement of air and heat along the channels created by the engineered I-beam structure of the ceiling, leading to heat and flames at the doorway to the first floor. •
With some of the other scenarios where a door or window is suddenly opened after a fire has started, the model showed how the timing of the door’s or window’s opening and the location of the opening could have a dramatic effect on the fire dynamics.
•
Using modeling in advance of experiments can potentially provide insights into better and more useful placement of sensors within the structure.
FIRE SAFETY ARTICLE/BASEMENT FIRE COMPUTER MODELING
Extending experimental and field data with innovative modeling
techniques is one way UL is helping advance safety science.
4
IMPACT This work was part of a 2010 DHS grant UL received. Our purpose was to help assess and advance the state of CFD modeling of compartment fires. In this research, compartment fires represent a residential basement with an unprotected engineered wood ceiling with a variety of openings. UL continues to support and advance the use of fire modeling tools for practical and important topics, such as the effect of different ventilation strategies on firefighting outcomes. Extending experimental and field data with innovative modeling techniques is one way UL is helping advance safety science.
RELATED ARTICLES Since you were interested in reading Basement Fire Computer Modeling, we thought you might find the following related articles of interest.
NEW DYNAMICS OF BASEMENT FIRES
ADVANCED COMPUTER MODELING
REDEFINING SMOKE
FIRE SAFETY ARTICLE/BASEMENT FIRE COMPUTER MODELING
5
SOURCES 1
Fahy, D.R, “U.S. Fire Fatalities in Structure Fires, 1977-2009,” National Fire Protection Association Fire Analysis and Research Division, 2010.http://www. nfpa.org/~/media/Files/Research/NFPA%20reports/Fire%20service%20 statistics/OSFatalitiesInstructures.pdf
2
“Our Most Hazardous Environment,” Fire Engineering, 3 Mar., 2011., http://www.fireengineering.com/articles/2011/03/fdic11-martin1.html.
3
Tabaddor, Mahmood, Ph.D.,” Fire Modeling of Basement with Wood Ceilings,” UL Research Paper, Dec. 2011. http://www.ul.com/global/documents/ offerings/industries/buildingmaterials/fireservice/basementfires/2009%20 NIST%20ARRA%20Appendix%20F%20-%20Fire%20Modeling%20of%20 Basement%20with%20Wood%20Ceiling.pdf.
4
Kerber, S., “Study of the Effectiveness of Fire Service Vertical Ventilation and Suppression Tactics in Single Family Homes,” UL Firefighter Safety Research Institute, 2013. Web: 7 Oct. 2013. http://ulfirefightersafety.com/wp-content/ uploads/2013/06/UL-FSRI-2010-DHS-Report_Comp.pdf.
5
Kerber S., Madrzykowski, D. et al., “Improving Fire Safety by Understanding the Fire Performance of Engineered Floor Systems and Providing Fire Service with Information for Tactical Decision Making,” UL Research Paper, March 2012. Web: 7 Mar. 2013. http://www.ul.com/global/documents/offerings/ industries/buildingmaterials/fireservice/basementfires/2009%20NIST%20 ARRA%20Compilation%20Report. pdf.
6
Tabaddor, Mahmood, Ph.D.,” Modeling the Thermal and Structural Behavior of Wood Beams in a Fire Environment,” UL Research Report, Dec. 2011. http:// www.ul.com/global/documents/offerings/industries/buildingmaterials/ fireservice/basementfires/2009%20NIST%20ARRA%20Appendix%20E%20 -%20Modeling%20the%20Thermal%20and%20Structural%20Behavior%20 of%20Wood%20Beams%20in%20a%20Fire%20Environment.pdf.
NEW SCIENCE FIRE SAFETY JOURNALS JOURNAL ISSUE 1
JOURNAL ISSUE 2
PV PANELS
WIRELESS CHARGING OF ELECTRIC VEHICLES
REDEFINING SMOKE
ADVANCED COMPUTER MODELING
LITHIUM-ION BATTERIES
STATISTICALLY PREDICTING ELECTRICAL ARCING
MODERN RESIDENTIAL FIRES
NEW DYNAMICS OF BASEMENT FIRES
ARTICLE INNOVATING FIRE ATTACK TACTICS
FIRE SAFETY ARTICLE/BASEMENT FIRE COMPUTER MODELING
6
To learn more, explore the New Science of Indoor Air Quality, Transaction Security, Sustainable Energy and Fire Safety. Watch our videos; read our journals, articles and case studies; scroll through our galleries; and meet our experts.
VISIT US ON UL.COM/NEWSCIENCE
[email protected] +1 847.664.2040
New Science Fire Safety cannot be copied, reproduced, distributed or displayed without UL’s express written permission. V.13. UL and the UL logo are trademarks of UL LLC © 2014
