Tuesday, June 27, 2017: 9:45 AM-10:45 AM
Building Life Safety Systems
Chair:
Paul Turnbull, Siemens Building Technologies, Inc.
Technical Committee: 5.6 Control of Fire and Smoke
Computational Fluid Dynamics (CFD) modeling is frequently used during the design phase of smoke control projects for building spaces that are too complicated to be done with hand calculations or zone models. Due to the extensive computing resources that would be required, CFD is generally not used to model entire buildings. This session covers three topics related to CFD models for smoke control system design. One paper explains how CFD models can be simplified in order to model large spaces, up to and including entire buildings. Another paper explains the use of CFD models for evaluating tenability within the space under consideration. The third paper walks through the design process of using a CFD model for smoke and heat spread, in combination with egress calculations, to determine a design which provides safe egress for occupants within a smoke-protected assembly seating area.
1 Tenability Analysis and Atrium Smoke Control (LB-17-C036)
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John Klote, P.E., John Klote Fire and Smoke Consulting |
Tenability analysis along with computational fluid dynamics (CFD) are recognized methods of atrium smoke control analysis by NFPA 92, Standard for Smoke Control Systems. Tenability analysis evaluates the following threats to life: toxic gas exposure, heat exposure, thermal radiation exposure, and reduced visibility. In dense smoke, people see poorly and often become disoriented which prolongs exposure time of the other threats. Also falls from balconies can result from reduced visibility. This paper discusses these threats as they apply to atria smoke control and how tenability analysis can be incorporated in CFD simulations of atrium smoke control systems.
2 CFD Modeling of Full-Size Highrise Fire Smoke Spread and Control (LB-17-C037)
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Liangzhu Wang, Ph.D., P.E., Concordia University |
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Dahai Qi, Concordia University |
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Shamim Mashayekh, Concordia University |
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Malek Soubra, Concordia University |
High-rise building fires often lead to disastrous and enormous losses if the fire smoke is not well controlled. This study uses the CFD model, Fire Dynamics Simulator (FDS) developed by the US National Institute of Standards and Technology (NIST), to model the fire smoke spreads and control strategies in a full-size high-rise building. The building is a 302-feet (92 meter) high-rise with two 20-story towers, three-story ground level parking spaces, two stairwells and one elevator shaft. The modeled fire smoke control system is a hybrid venting system with mechanical fan installed at the top of the stairwells. Neutral plane level, smoke temperature and smoke flow inside the building were studied based on the simulation.
3 Computational Fluid Dynamics (CFD) Analysis of Smoke Protected Seating (LB-17-C038)
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Jennifer L. Wiley, P.E., JENSEN HUGHES Inc. |
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Michael J. Ferreira, P.E., JENSEN HUGHES Inc. |
The International Building Code and the Life Safety Code (NFPA 101) recognize that smoke-protected assembly seating, which is not subjected to smoke accumulation within or under a structure, subjects occupants to a lesser hazard from the accumulation of smoke and fumes during a fire event. The codes therefore have less-stringent requirements for design and layout of the means of egress for smoke-protected assembly seating, including reduced aisle widths per seat served and greater maximum travel distances. These less-stringent requirements provide increased use of space and flexibility in the design of assembly seating. This paper provides an overview of the use of CFD models in the design of smoke control systems for smoke-protected seating. Examples of smoke-protected seating in various settings, including arena seating and large theaters, are also discussed.