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Reddit.com – mealsharedotorg
Floor Chris Campbell, PE Senior Fire Engineer Reddit.com - - PowerPoint PPT Presentation
Floor Chris Campbell, PE Senior Fire Engineer Reddit.com - - PowerPoint PPT Presentation
The Impact of Stairwell Queues on Egress Time From a Floor Chris Campbell, PE Senior Fire Engineer Reddit.com mealsharedotorg Stairwell Queues 2 Thunderhead Engineering Stairwell Queues 3 Associated Press Stairwell Queues 4
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Thunderhead Engineering
Stairwell Queues
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Associated Press
Stairwell Queues
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- Estimates egress times using
- ccupant velocities and flow
rates through egress components
- Flow rates limited by a
maximum specific flow
- In merging of flows, sum of
flow rates in = flow rate out
SFPE Hydraulic Model
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- If queuing at the stair/floor landing occurs faster than expected, will there be an impact
to all floors above that point?
- Taller the building, the greater the effect?
- Do model building codes account for this with any egress requirements based on number
- f stories/height?
Driving Questions
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- IBC requires one additional exit for buildings taller than 420 feet
- NFPA 101 allows for a reduction in egress width factors for stairs wider than 44 inches
- NFPA 101 increases minimum stair width to 56” for stairs serving a cumulative occupant
load of 2,000 persons or more
Model Code Requirements in US
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- 2 exit stairs available to all
- ccupants
- All occupants begin evacuation
simultaneously
- First floor occupants not
considered
Egress Model Construction
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- Simulations ranging from 2-12
stories
- All simulations performed in
both SFPE and Steering modes
- Exit discharge located at bottom
- f each stairwell
Egress Model Construction
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- First floor occupants not
considered
Egress Model Results
200 400 600 800 1000 2 3 4 5 6 7 8 9 10 11 12 Time (sec) Number of Stories
SFPE Mode
Total Building Egress
Max Time to Clear Floor
Mean Time to Clear Floor
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- First floor occupants not
considered
Egress Model Results
200 400 600 800 1000 2 3 4 5 6 7 8 9 10 11 12 Time (sec) Number of Stories
Steering Mode
Total Building Egress Max Time to Clear Floor Mean Time to Clear Floor
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- Total egress time is proportional to number of stories (as expected)
- Mean and maximum time to clear a floor also proportional to number of stories
- Potential solution – partial evacuation?
Conclusions
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- Expand scope of modelling analysis to taller buildings and more complex floor geometry
- Study real building evacuation data and determine if the same trend exists
- Code development community should consider these trends in future code cycles for