Accounting for Emergency Response in Building Evacuation: Modeling Differential Egress Capacity Solutions.
Accounting for Emergency Response in Building
Evacuation: Modeling Differential Egress Capacity
Solutions.
(158 K)
Averill, J. D.; Song, W.
NISTIR 7425; 13 p. April 2007.
Keywords:
evacuation; egress; emergencies; response time; fire
fighters; first responders; stairways; occupants;
evacuation time; stairwells; simulation; fire drills;
office buildings; high rise buildings; equations;
validation; scenarios
Abstract:
The impact of firefighter response on the progress of
the building evacuation is not typically considered.
Responders use of the stairs while occupants are
evacuating can significantly increase total building
evacuation time. To account for emergency response,
this analysis considered whether adding. capacity
through extra stairwell width was equivalent to
providing the same total egress capacity through an
additional stairwell. An egress simulation with a
counterflow submodel was calibrated against recent
fire-drill experimental results to demonstrate the
capability of the model to produce meaningful evacuation
results. The model was then applied to a hypothetical 50
story office building with 350 occupants per floor. When
comparing equivalent total width, additional stairwells
outperform wider stairwells from the perspective of
evacuation performance, as well as firefighter ascent
times. A third stairwell can completely mitigate the
effect of firefighter response or even improve the
building evacuation time compared to two stairwells with
no firefighter response. Background: The ICC Terrorism
Resistant Buildings (TRB) Committee has proposed a
change to Section 403 of the International Building Code
(IBC), which would require one additional stairwell (one
greater than otherwise required) for all high-rise
buildings (other than R-2) taller than 420 ft (128 m).
The proposal would provide greater egress capacity than
currently required, recognizing that one stairwell may
become unusable during evacuation due to the
introduction of smoke and heat and blockage by fire
hoses once suppression operations begin. Objective:
Perform computer egress modeling to provide quantitative
comparisons of different stairwell configurations with
and without emergency response interaction. Model
Description: The computer model is a modified form of a
biased random walk model without back step. The model is
defined in a two-dimensional grid, of which each site
can be occupied by a pedestrian or be empty. Each
pedestrian can move to a neighboring site with certain
probabilities. Usually, every pedestrian has a drift to
move to the preferential site. All the possible
configurations of downward walkers are demonstrated in
Figure 1. The movement probabilities can be calculated
with Equation 1.
