Fire and Life Safety Report
Building Name:
Performing Arts Center
California Polytechnic State University, Building 6
1 Grand Ave., San Luis Obispo, CA 93407
Prepared by:
Kristen Dentici
Cal Poly Fire Protection Engineering
FPE 521: Egress Analysis and Design
December 1, 2020
Table of Contents
Introduction .................................................................................................................................................. 3
Building Description .................................................................................................................................. 4
Applicable Codes and Standards ............................................................................................................... 5
Fire Protection Systems ............................................................................................................................ 6
Occupancy Analysis ....................................................................................................................................... 6
Occupant Load Factor ............................................................................................................................... 6
Occupant Load .......................................................................................................................................... 7
Prescriptive Egress Analysis ........................................................................................................................ 13
Egress from Rooms ................................................................................................................................. 13
Egress from Floors................................................................................................................................... 16
Number and Arrangement of Exits ......................................................................................................... 23
Travel Distance, Common Path, and Dead-End Corridors .................................................................. 23
Number and Spacing of Exits .............................................................................................................. 26
Other Miscellaneous requirements ........................................................................................................ 32
Boiler room ......................................................................................................................................... 32
Assembly Fixed Seating ....................................................................................................................... 33
Exit Signage ............................................................................................................................................. 33
Fire Resistance and Interior Finish .............................................................................................................. 37
Fire Resistance Requirements................................................................................................................. 37
Interior Finish Requirements .................................................................................................................. 37
Performance-Based Egress Analysis ........................................................................................................... 40
Pre-Movement Time ............................................................................................................................... 41
The Protective Action Decision Model (PADM) .................................................................................. 41
Factors That Influence Occupant Behavior ......................................................................................... 42
Pre-Movement Time ........................................................................................................................... 43
Movement Time...................................................................................................................................... 43
Tenability Analysis Criteria ...................................................................................................................... 51
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Introduction
This report is intended to discuss and analyze the fire and life safety systems of the Cal Poly Performing
Arts Center. This report will cover the egress requirements for the building. First, the occupant loads of
rooms and floors are determined which will later be used to determine whether the provided exits are
enough by a code-based analysis and a performance-based analysis. Additionally, locations of exit signs,
interior finish and fire resistance requirements, and tenability performance criteria are discussed.
Figure 1. Performing Arts Center from Southeast direction https://pactech.calpoly.edu/
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Building Description
The Performing Arts Center (PAC) is located on the California Polytechnic State University, San Luis Obispo
campus. The building is located west of Grand Ave. and is near a large parking garage and another smaller
theater as shown below.
Figure 2. Satellite View of PAC (circled in red) with surrounding buildings and roads
The PAC opened in September of 1996 and includes The Christopher Cohan Center including Harman Hall,
a 180-seat classroom Philips Hall, and the Rehearsal/Multi-purpose Pavilion. Alex and Faye Spanos theater
is located in the back of the PAC, and the Christopher Cohan Center is located adjacent to the Davidson
Music Center but neither are included in this report as they are considered separate buildings. The
following provides more information on the construction of the building:
•
•
•
Number of stories: 4 total, 1 below grade
Date of Construction: 1996
Construction Type: IB
The building consists of multiple occupancy classifications, with the main occupancy being A-1 in Harman
Hall. The following tables specify all the occupancy types found in the building and a summary of the
occupant load on each floor.
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Table 1. Occupancy Classifications
Occupancy Classification
Theater
Lecture Halls
Exhibition Halls
Name
A-1
A-3
A-3
Rooms Included
Harman hall
Philips Hall
Lobby, Rehearsal Pavilion
Business
B
Accessory areas (dressing
rooms, security,
communications)
Storage
S-2
Storage Areas, Lift Pit
Table 2. Occupant load by floor
Floor
Trap Room/Pit Level
Orchestra
Main Entry/Lobby Level
Lower Balcony Level
Upper Balcony Level
Use
Storage, Equipment, Chair
Wagon Lift
Occupant Load
Main Hall, Loggias, Stage,
Dressing Rooms, Rehearsal
Pavilion, Classroom
Dress Circle, Lobby,
Reception, Concessions
Balcony, Lounge, Control
and Sound Room
Balcony, Storage
Total:
33
1901
774
244
158
3110
The building construction is considered Type IB. The following fire resistance hour ratings are required for
building elements (other requirements for stairs and corridors discussed later in report):
•
•
•
•
•
Primary Structural Frame: 2
Bearing Walls (exterior and interior): 2
Nonbearing walls and partitions: 0
Floor construction: 2
Roof construction: 1
These requirements do not relate specifically to this report, however they have an impact on
requirements for enclosed shafts.
Applicable Codes and Standards
The PAC was built to the required codes at the time of permitting, as follows:
•
•
•
•
California Building Code (1992)
California Fire Code (1992)
California Electrical Code (1991)
California Mechanical Code (1992)
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•
California Plumbing Code (1991)
While the building was built to these specifications, they will not be referenced for this report. For the
purposes of this report, the current version (2018) of the International Building Code (IBC) will be used.
Fire Protection Systems
In order to perform an egress analysis of the Performing Arts Center, some of the basic fire protection
systems must be addressed as they affect design specifications. The PAC includes an automatic sprinkler
system, fire alarm and voice communications system, and smoke protected assembly seating.
The fire sprinkler system for the building is based on the hazard groups present. The office areas and
auditorium are classified as Light Hazard Occupancies; the storage areas, kitchen, and mechanical
equipment areas are classified as Ordinary Hazard Group 1; and the stage and orchestra pit are classified
as Ordinary Hazard Group 2.
The building is equipped with a fire detection and alarm system. The fire alarm system consists of the
following detection devices: manual pull stations, automatic sprinkler water flow indicators, automatic
smoke detectors, and automatic heat detectors. Manual pull stations are located adjacent to all stair doors
and stage exits and within 200 feet along each exit path. Upon alarm activation, a pre-recorded message
announcement will be played. Additionally, strobe devices (visual warning devices) are placed in
restrooms, corridors, lobbies, meeting rooms, and other public areas.
Finally, the building is equipped with assembly smoke protected seating in the form of stage smoke
removal and fire barrier. The fire barrier is provided by a proscenium wall with 2-hour fire rated
construction. It should be noted that only two openings of less than 25 sq. ft. are allowed into the
auditorium from the stage. In addition to the fire barrier, smoke removal is provided through gravity vents
located near the center and at the highest point above the stage. The vents are activated by a fusible link
and cover more than 5% of the stage area, as required by code.
These fire protection systems will be discussed further in their role in the design of egress and life safety
systems.
Occupancy Analysis
In order to perform both the prescriptive and performance analysis, the occupant load of each room and
floor must be calculated. The occupant load of each room is calculated by one of two methods:
occupant load factor and area, or number of fixed seats.
Occupant Load Factor
The occupant load factor for each room is based on Table 1004.5 in the IBC. There are two types of floor
areas that can be used in calculations: net and gross. Gross floor area refers to “the floor area within the
inside perimeter of the exterior walls of the building under consideration, exclusive of vent shafts and
courts, without deduction for corridors, stairways, ramps, closets, the thickness of interior walls,
columns or other features.” Net floor area refers to “the actual occupied area not including unoccupied
accessory areas such as corridors, stairways, ramps, toilet rooms, mechanical rooms, and closets.” When
there is multiple occupant load factors in a building that combine net and gross, the following
calculations are made:
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•
•
Apply the gross area figure to the gross area of the portion of the building devoted to the use for
which the gross area figure is specified, and
Apply the net area figure to the net area of the portion of the building devoted to the use for
which the net area figure is applied.
The following occupant load factors were used:
•
•
•
•
•
•
•
Main Hall, loggias, Dress Circle, balconies, classrooms: Assembly with fixed seating, number of
fixed seats
Storage, machine rooms/electrical/mechanical, etc. (where included), equipment room:
Accessory storage areas, mechanical equipment room, 300 gross sq.ft/person
Piano, stage: Stage, 15 net sq.ft./person
Lobby, founder’s lounge: Unconcentrated assembly, 15 net sq.ft./person
Restrooms (where included), wardrobe, service, workroom, reception: Business, 150 gross
sq.ft./person
Concession, communications: Concentrated business, 100 gross sq.ft./person
Dressing Rooms: Locker room, 50 gross sq.ft./person
Rooms that are not included in net calculations but are included in gross calculations were included or not
included based on the nearest adjacent occupancy. For bathrooms connected/adjacent to areas such as
dressing rooms, they were included in the calculation. However, for bathrooms located near the Main Hall
areas, they were not included because they were considered part of the net occupancy area. Similarly,
mechanical rooms, electrical rooms, etc. were included if they were separated from any other occupancy,
or if they were in the area with gross area measurements.
Occupant Load
The occupant load for each room was calculated by dividing the appropriate floor area by the occupant
load factor and rounding up. Rounding up provides a more conservative approach to simply rounding or
rounding down. The occupancies and occupant loads for each room as well as stairs and corridors are
shown in the following figures by floor. To obtain floor occupant loads, the room occupancies were
summed.
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Figure 3. Trap room/lift pit level room occupancies.
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Figure 4. Orchestra level room occupancies. Note: Restrooms adjacent to cast prep areas are included in those rooms occupant load.
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Figure 5. Main Entry/Lobby level room occupancies.
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Figure 6. Lower Balcony level room occupancies.
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Figure 7. Upper Balcony level room occupancies.
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Prescriptive Egress Analysis
The prescriptive egress analysis for this building is based on the IBC Chapter 10. In order to meet the
requirements of the IBC, egress capacity is compared to occupant load for each room and for each floor
as a whole. In addition, arrangement of exits in order to account for acceptable common path distance,
travel distance, dead end length, and separation of exits is checked. In certain areas and on certain floors,
a specific number of exits are required, and this was checked as well. Finally, recommendations for the
placement of exit signage will be included.
Prescriptive egress capacity is based on the size of egress components such as doors, corridors, ramps,
and stairs. Since the building is equipped with an automatic sprinkler system throughout and voice alarm
communication, the egress capacities are allowed to be increased per IBC Chapter 10. Stairway capacity
is calculated with a capacity factor of 0.2 inch per occupant and other egress components such as door
capacities are calculated with a capacity factor of 0.15 inch per occupant.
Egress from Rooms
The calculation of room occupant load was discussed earlier in this report. Next, the doors in each room
were measured and divided by the capacity factor to determine the egress capacity for each room. The
capacity of egress from each room must be equal to or greater than the occupant load for the room. The
following tables summarize the egress capacity of each room and whether the capacity is enough.
Additionally, in spaces where one form of egress led to another, the egress component with lower capacity
was used.
Table 3. Room egress capacity for trap room and pit level.
Floor
Room
Use
10
Trap Room
(Below)
11 Trap Room
12A/B
Trap
Room
and Lift
Pit
Capacity
Occupant
Egress
Factor
Exit
Load in
Sufficient?
Available (in./perso Capacity
Room
Notes
n)
Need to egress room 10&room 11.
8 2 X 36" Doors 0.15
480 YES
Capacity needed: 19
11 132",36" Doors 0.15
1120 YES
12 Storage
1 36" Door
0.15
240 YES
Machine Room
13 Pump Room
14 Electrical
1 36" Door
1 36" Door
2 36" Door
0.15
0.15
0.15
240 YES
240 YES
240 YES
15 Electrical
1 72" Door
0.15
480 YES
16 Mech. Room
1 36" Door
0.15
240 YES
17 Plumbing Room
2 72" Door
0.15
480 YES
18 Mech. Room
3 72" Door
0.15
480 YES
19 Electrical
2 36" Door
0.15
240 YES
Room 11 egress through room 10
Need to egress room 12 & 12A/B.
Capacity needed: 2
Room 12A/B egress through room
12
Egress directly to public way. Not
included in floor level calculation
Egress directly to public way. Not
included in floor level calculation
Egress directly to public way. Not
included in floor level calculation
Egress directly to public way. Not
included in floor level calculation
Egress directly to public way. Not
included in floor level calculation
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Table 4. Room egress capacity for orchestra level.
Floor
Room
100
101
101A
101B
101C
101D
102
103
104
105
106
107
108
109
110
110A
111
111A
112
113
113A
Orchestra
114
115
116
117
118
119
120
120A/B
121
122
123
Use
Lounge/Galleries
Occupant
Egress
Load in
Available
Room
0
Main Hall
Storage
Loggia East
Loggia West
Piano
Stage
Restroom
Electrical
Storage
Storage
Storage
Food Handling
Green Room
Dressing Room
Dressing Room
Dressing Room
Dressing Room
Manager/Receiving
Security
Security
Wardrobe
Dressing Room
Wardrobe
Dressing Room
Dressing Room
Dressing Room
Dressing Room
Restroom
Dressing Room
Wardrobe
Janitor
846
1
10
11
12
270
6
1
1
3
1
5
4
2
2
2
2
1
1
1
4
6
5
13
8
13
9
2
4
4
1
124
Classroom
180
124B
125
126
127
Classroom
Restroom
Restroom
Storage
1
1
1
1
128
129
130
131
132
133/134
Rehearsal Pavilion
Janitor
Electrical
Storage
Restroom
Restroom
455
1
1
1
3
5
60" Door, 2X
144" Stair, 2
X 66" Doors
2 X 36"
Door,
2 X 72" Door
72" Door
39" Stair
39" Stair
72" Door
5 X 36" Door
36" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
90" Door
32" Door
2 X 90" Door
32" Door
32" Door
32" Door
32" Door
32" Door
32" Door
90" Door
32" Door
32" Door,
72" Door
90" Door,
66" Door
32" Door
32" Door
32" Door
108" Door,
4 X 42" Door
32" Door
32" Door
32" Door
32" Door
32" Door
Capacity
Factor
Exit
Sufficient?
(in./perso Capacity
n)
Notes
See floor Where doors/corridors lead to
level
stairs, the most conservative
calculation capacity along path is used
0.15
0.15
0.2
0.2
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
1440
480
195
195
480
1200
240
213
213
213
213
213
213
213
213
213
213
213
213
213
600
213
1200
213
213
213
213
213
213
600
213
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
693 YES
0.15
0.15
0.15
0.15
1040
213
213
213
YES
YES
YES
YES
0.15
0.15
0.15
0.15
0.15
0.15
1840
213
213
213
213
213
YES
YES
YES
YES
YES
YES
Egress through main hall
Egress shared with main hall
Egress shared with main hall
Egress through main hall
Required capacity includes 110A
Egress through 110
Required capacity includes 111A
Egress through 111
Required capacity includes 113A
Egress through 113
Required capacity includes 124B
Egress through 124
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Table 5. Room egress capacity for entry and lobby level.
Floor
Room
Entry Lobby
Use
200
Lobby
593
201
201A
201B
Dress Circle
Organ
Royal Box
133
1
6
202
203
203A
204
Concession
Boiler Room
Boiler Room
Electrical
Communications
Room
205
206
207
207A
208 (A,B,C,D)
Capacity
Factor
Exit
Sufficient?
(in./perso Capacity
n)
Occupant
Load in Egress Available
Room
Mech. Room
Electrical
Electrical
Reception
9 X 60" Door, 32"
Door
2 X 32" Door
32" Door
32" Door
0.15
3813 YES
0.15
0.15
0.15
426 YES
213 YES
213 YES
32" Door
3
3 72" Door
2 2 X 32" Door
4 72" Door
0.15
213 YES
0.15
0.15
0.15
480 YES
426 YES
480 YES
32" Door
0.15
213 YES
0.15
613 YES
0.15
0.15
0.15
426 YES
426 YES
360 YES
4
6
9
3
7
60" Door, 32"
Door
2 X 32" Door
2 X 32" Door
2 X 36" Door
Notes
Egress capacity including 203A
Egress through 203
Converge into 2 stairs (44" and 36"),
capacity 400 (acceptable)
A,B,C,D converge into main room
Table 6. Room egress capacity for lower balcony level.
Floor
Room
Use
300 Circulation
301 Lower Balcony
Control/
Sound Room
303 Storage
302
Balcony Level
304 Founder's Lodge
305
306
307
308
309
310
311
312
313
314
Service
Restroom
Storage
Main Communication Room
Organ Blower Room
Electrical
Storage
Workroom
Restroom
Storage
Capacity
Occupant
Egress
Factor
Exit
Load in
Sufficient?
Available (in./perso Capacity
Room
n)
172 4 X 32" Door
0.15
5 30" Door
0.15
1 30" Door
0.15
Notes
See floor
350 level
Door leads to stair but
calculation stairs are limiting factor
Doors connect to stairs
852 YES
but doors are limiting
factor
Stairs lead to door but
200 YES
door is limiting factor
200 YES
45 66" Door
0.15
440 YES
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.2
0.15
0.15
200
200
200
200
200
480
200
210
200
200
0 70" Stair
2
3
1
2
1
1
1
6
3
1
30" Door
30" Door
30" Door
30" Door
30" Door
2 X 36" Door
30" Door
42" Stair
30" Door
30" Door
0.2
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
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Table 7. Room egress capacity for gallery (upper balcony) level.
Floor
Room Use
400 Circulation
Gallery
401
402
403
404
405
406
Upper Balcony
Storage
Storage
Storage
Equipment Room
Equipment Room
Capacity
Occupant
Egress
Factor
Exit
Load in
Sufficient? Notes
Available (in./perso Capacity
Room
n)
0 32" Door
152
2
1
1
1
1
4 X 30" Doors
30" Door
30" Door
30" Door
30" Door
30" Door
0.15
0.15
0.15
0.15
0.15
0.15
0.15
See floor
level
213 calculation
800
200
200
200
200
200
YES
YES
YES
YES
YES
YES
Doors lead to stairs
but doors are
limiting factor
As seen in the above tables, the PAC meets the 2018 IBC requirements for room egress capacity. However,
it should be noted that the IBC has a minimum door clear width of 32” (IBC 1010.1.1) and a minimum stair
width of 44” (IBC 1011.12). Some doors in this building are equipped with 30” doors, so while they serve
a sufficient capacity for the rooms, they are not large enough to meet the overall door requirement.
Additionally, some rooms may require a minimum number of doors and door separation, which will be
discussed later in this report.
Egress from Floors
In addition to requiring sufficient capacity for egress from each room, each floor is required to provide
sufficient capacity for the total occupant load on that floor. The following figures show the egress paths
from main occupied areas to floor level exits.
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Figure 8. Floor level exits for pit level and trap room level.
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Figure 9. Floor level exits for orchestra level.
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Figure 10. Floor level exits for main entry and lobby level.
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Figure 11. Floor level exits for balcony level.
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Figure 12. Floor level exits for gallery (upper balcony) level.
Next, the floor level exit capacity was found by calculating the individual capacity of each floor level exit
and summing the capacities. Where there were two egress components in series, the lowest capacity was
used. The following table summarize the occupant load of each floor and the egress capacity that is
available. Additionally, some floors will require a certain number and spacing of exits which will be
addressed in the following section.
Table 8. Floor egress capacity for trap room and pit level.
Floor
Trap Room
and Lift Pit
Door/
Occupant Doors/
Corridor Stairs
Load
Corridors
Capacity
24
2 X 36"
480
2 X 48"
Floor Capacity
Stair
(Smallest value
Capacity between doors,
corridors, stairs)
480
480
Sufficient?
YES
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Table 9. Floor egress capacity for orchestra level.
Occupant
Load
Floor
Orchestra
1901
Egress
Available
Floor Exit
(Smallest
Sufficient?
Capacity
capacity along
path)
3 X 72" Door,
32" Door, 2 X
66" Door, 90"
Stair
2983
YES
Table 10. Floor egress capacity for main/entry level.
Egress
Available
Occupant
(Smallest
Load
capacity
along path)
Floor
Main/Entry
Level
774
Floor Exit
Sufficient?
Capacity
9 X 60" Door,
32" Door
3813
YES
Table 11. Floor egress capacity for balcony level.
Floor
Balcony
Level
Egress
Available
Occupant
(Smallest
Load
capacity
along path)
244
3 X 70" Stair
Floor Exit
Sufficient?
Capacity
1050
YES
Table 12. Floor egress capacity for gallery (upper balcony) level.
Floor
Gallery
(Upper
Balcony)
Level
Egress
Available
Occupant
(Smallest
Load
capacity
along path)
244
3 X 32" Door
Floor Exit
Sufficient?
Capacity
639
YES
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As seen in the tables above, the exit capacity of each floor was found to be sufficient. In addition to the
requirement for each floor to have sufficient egress, since this building’s main occupancy is assembly, the
main exit is required to meet half of the occupant load for the building (IBC 1029.2). This building has
multiple main exits spread along the perimeter of the building which serve a capacity of 3813 occupants.
This exceeds the total building occupancy of 3110 occupants and therefore meets the requirement.
Number and Arrangement of Exits
In addition to the exits being sufficient for the capacity of occupants in the building, the locations and
numbers of exits must be considered in the following manners: travel distances, common paths, and dead
ends; minimum number of exits from highly occupied spaces; and spacing of multiple exits.
Travel Distance, Common Path, and Dead-End Corridors
Chapter 10 of the IBC specifies maximum lengths for travel distance to an exit, common path lengths, and
dead-end corridor lengths based on the occupancy and other factors for the building. A common path of
egress travel is defined by the IBC as “that portion of exit access travel distance measured from the most
remote point of each room, area, or space to that point where the occupants have separate and distinct
access to two exits or exit access doorways.” Therefore, common path requirements only apply to spaces
with one exit. The travel distance is the distance that it takes an occupant to reach the exterior of the
building or a protected path of egress travel (such as a smoke protected stairway). Since this building does
not separate the occupancies on each floor, the most restrictive requirements must be met which are
those for an assembly occupancy except for the trap room and pit level which is storage occupancy. The
following table provides the requirements for the three types of measurements considered for assembly
occupancies.
Table 13. Travel distance requirements for assembly occupancy.
Measurement Requirement Code Section
Common Path
75 feet
1006.2.1
Travel Distance
250 feet
1017.2
Dead End
20 feet
1020.4
For smoke protected assembly seating, the requirements for travel distance are slightly different. The
total exit distance must be less than 400 feet, with up to 200 feet to reach a vomitory or concourse and
up to 200 feet to reach an exit.
For the trap room and pit level, the largest travel distance is shown below.
Figure 13. Trap room and pit level longest travel distance.
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The trap room and pit level is subject to the requirements for a storage occupancy which are as follows:
common path, 100 feet; and travel distance, 250 feet. There are no dead-end corridors on this floor. As
seen in the above figure, the largest travel distance in the trap room and pit level is 145 feet, which is
acceptable. The largest common path in this room is 84 feet which is also acceptable.
Figure 14. Orchestra level longest common path and travel distance.
On the orchestra level, the longest travel distance is 199 feet which originates in the main hall and exits
near the classroom. This is shorter than the maximum allowed travel distance for smoke-protected
assembly seating of 400 feet. The longest common path is found in the restroom in the lower left corner
and is 60 feet which is lower than the maximum allowed. There are no dead ends on this level.
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Figure 15. Main/entry level longest travel distance.
On the main lobby level, there are not many long egress paths. There are no large rooms with a single
exit, so the common path requirement is met. The longest travel distance on this level is from the dress
circle seating, which is 142 feet in length and less than the maximum of 400 feet. There are no dead ends
on this level.
Figure 16. Balcony level longest travel distances.
On the balcony level, there are no lengthy common paths and no dead-end corridors. The longest travel
distance is from the lower balcony seating and is 139 feet, which is less than the 400-foot maximum.
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The gallery (upper balcony) level is very similar in construction to the lower balcony level and none of the
three requirements were exceeded on this level either. Therefore, each level of the PAC meets the
requirements for travel distance, common path, and dead-end corridors.
Number and Spacing of Exits
In addition to limiting the travel distances, there are requirements for the number and spacing of exits
within areas of floors and on floors. For rooms of assembly occupancy and less than 50 occupants, one
exit per room is permitted so long as the common path does not exceed 75 feet. For business and storage
occupancies that are sprinkler protected, one exit is permitted so long as the common path does not
exceed 100 feet. All common paths were already checked and did not exceed 75 feet. Additionally, all
spaces with one exit had occupant loads of less than 50. For occupant loads greater than this and up to
500, 2 exits are required. For occupant loads between 501 and 1,000 three exits are required and four are
required for occupant loads greater than 1,000 (IBC 1006.2). Balconies, galleries or press boxes having
more than 50 seats must have two means of egress with one from each side (1029.5). In addition to
providing multiple exits, two of the exits must be placed at least one third of the overall diagonal of the
space apart. When there are three or more exits, the additional exits must be spaced reasonably.
The following spaces require more than one exit. The list gives the number of exits supplied and the
number of exits (required), as well as figures with exit spacing:
•
Main Hall: 4 provided (3 required)
•
Stage: 5 provided (2 required)
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•
Rehearsal Pavilion: 4 provided (2 required)
•
Classroom: 2 provided (2 required)
•
Dress Circle: 2 provided (2 required)
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•
Lobby: 5 provided (3 required, however more will likely be required for egress from floor, see next
section)
•
Lower Balcony: 4 provided (2 required)
•
Upper Balcony: 4 provided (2 required)
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All of the areas have a proper number and spacing of exits. Chapter 10 of the IBC also states requirements
for the amount and spacing of floor level exits. The table below shows the required number of exits based
on the floor occupant load.
Table 14. IBC Table 1006.3.2. Number of exits required from each story.
Additionally, a single exit may be allowed in certain occupancies with low loads. For this building, this
applies to the trap room and pit level, based on IBC Table 1006.3.3(2). The same separation of exits
requirement as above are required on a floor level as well. Based on this information, the following is the
required number of exits from each story along with the number provided and a figure showing separation
distance:
•
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•
Trap room/pit level: 2 provided (1 required)
•
Orchestra level: 7 provided (4 required)
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•
Main/entry level: 10 provided (3 required)
•
Lower balcony level: 3 provided (2 required)
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•
Gallery (upper balcony) level: 3 provided (2 required)
As seen, each story of the PAC meets the requirement for number of exits and exit separation.
Other Miscellaneous requirements
Boiler room
In addition to other requirements, boiler rooms are required to have two exit doors when the area is over
500 square feet and any fuel-fire equipment exceeds 400,000 BTU. One of the exits can be a fixed ladder
and the exits must be at least half the diagonal of the space apart. The figure below shows that the boiler
room located on the entry/lobby level of the building meets these requirements.
Figure 17. Boiler room exit layout.
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Assembly Fixed Seating
In assembly occupancy with fixed seating, IBC Chapter 10 specifies a capacity of the aisles, similarly to
how the capacity of a door is calculated. The capacity of the aisle is determined by multiplying the width
of the aisle by a factor from IBC table 1029.6.2 (See table below) because the assembly seating is smoke
protected. The factor used is based on total number of seats within the space exposed to smoke-protected
environment and the type of aisles.
Table 15. IBC Table 1029.6.2, capacity factor for aisles in assembly smoke-protected seating.
Since the Main Hall seats less than 5,000 persons and the aisles have a slope of 1:12, the capacity factor
of 0.15 inches/person is used. In the main hall seating area, the aisles are 44 inches wide on each side of
the seating areas, therefore each aisle can serve a capacity of 293 occupants. These aisles must also
comply with the requirements of 1029.9.1 which specifies a minimum aisle width for aisles leading to an
exit to be 42”, which is met.
For seating in rows, there is also a requirement for the clear width of the aisles between the rows. The
required width of the aisle is based on the number of seats and whether there are aisles or doorways at
one or both ends of the row. For rows where there is an aisle at both ends, the minimum clear width is 12
inches, and the row width must be increased by 0.3 inch per seat beyond 14 seats. For rows where there
is only an aisle or door at one end, the row width is increased by 0.3 inches from 12 inches for each seat
in addition to 7. The minimum clear width is not required to exceed 22 inches, however. In the PAC, the
balcony and dress circle seating have 22” clear widths and therefore meet the requirement. In the
orchestra level, the longest row is 42 seats, which means that the required clear width is 20.4 inches. The
orchestra seating has 21-inch clear width aisles, so this requirement is met.
Exit Signage
Chapter 10 of the IBC provides requirements for the locations of exit signs within a building. According
to IBC 1013.1, exit signs must be placed in the following locations:
•
•
•
•
Exit and exit access doors
Path of egress travel to exits and within exits to indicate direction of travel when path/exit are
not immediately visible
Must be placed such that at any point in an exit access corridor, there is an exit sign within 100
feet or the listed viewing distance (whichever is less).
Not required in rooms or areas that only require one exit or exit access.
Following these requirements, suggest locations for exit signs are provided in the figures following.
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Figure 18. Exit sign locations for lift pit and trap room level.
Figure 19. Exit sign locations for orchestra level.
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.
Figure 20. Exit sign locations for main entry/lobby level.
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Figure 21. Exit sign locations for lower balcony level.
Figure 22. Exit sign locations for gallery (upper balcony) level.
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Fire Resistance and Interior Finish
Fire Resistance Requirements
The fire resistance requirements for egress components is given in Chapter 10 of the IBC. The required
corridor fire resistance is given by the table below.
Table 16. (IBC Table 1020.1) Required fire-resistance rating for corridors.
Based on this, the PAC is not required to have a fire resistance rating in corridors since it is assembly
occupancy and equipped by an automatic sprinkler system. The stairways and shafts in this building are
required to be protected by a fire resistance rating of at least 2 hours according to IBC 713.3 because they
connect 4 stories or more. Per IBC Table 716.1 (2), the doors connecting to the 2-hour shafts must be 1 ½
hour rated.
Interior Finish Requirements
The interior finish requirements for this building are based on IBC Chapter 8. There are some general and
some occupancy specific requirements. Floor and wall finishes are tested using the following methods:
•
•
NFPA 286:
o Description of test: Full-scale room-corner test, wall materials installed on walls or ceiling
material installed on ceiling. 40 kW gas burner is placed in corner for first five minutes,
then 160 kW fire for additional 10 minutes
o Acceptance criteria (IBC 803.1.1.1):
▪ During the 40 kW exposure, flames shall not spread to ceiling.
▪ The flame shall not spread to the outer extremity of the sample on any wall or
ceiling.
▪ Flashover, as defined in NFPA 286, shall not occur.
▪ The peak heat release rate throughout the test shall not exceed 800 kW.
▪ The total smoke released throughout the test shall not exceed 1,000 m2.
o Acceptance above is considered to also comply with Class A requirements of ASTM
E84/UL 723.
NFPA 265:
o Description of test: Room-corner test for textile wall covering installed on walls. Gas
burner is placed in corner at 40 kW for 5 minutes then 150 kW for an additional 10
minutes.
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o
•
Acceptance criteria (IBC 803.5.1.1):
▪ During the 40 kW exposure, flames shall not spread to the ceiling.
▪ The flame shall not spread to the outer extremities of the samples on the 8-foot
by 12-foot walls.
▪ Flashover, as defined in NFPA 265, shall not occur.
▪ The total smoke release throughout the test shall not exceed 1,000 m2.
ASTM E84/UL 723:
o Description of test: Steiner tunnel test. Horizontal test specimen is placed in a tunnel and
the flame spread down the tunnel is recorded. Smoke-developed index is also measured.
Results are in terms of Class A, B, or C with A being the lowest flame spread.
o Description of classes (IBC 803.1.2):
▪ Class A: Flame spread index 0-25; smoke-developed index 0-450.
▪ Class B: Flame spread index 26-75; smoke-developed index 0-450.
▪ Class C: Flame spread index 76-200; smoke-developed index 0-450.
Certain interior finishes, such as high-density polyethylene (HDPE), have specific requirements that are
held across all occupancies. This is summarized in the table below.
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Table 17. Interior ceiling and wall finish requirements for all occupancies
Finish Material/Type
Test Standard (Requirement)
Material less than 0.036
Not required to be tested
inch thick
Foam plastics
Not allowed (Exception: IBC 2603.9)
NFPA 265: Meet all requirements listed in IBC
803.5.1.1 (see above)
NFPA 286: Meet all requirements listed in IBC
Textile wall covering
803.1.1.1 (see above)
ASTM E84/UL 723: Class A and must be protected
with automatic sprinkler system
NFPA 286: Meet all requirements listed in IBC
803.1.1.1 (see above)
Textile ceiling coverings
ASTM E84/UL 723: Class A and must be protected
with automatic sprinkler system
NFPA 265: Meet all requirements listed in IBC
803.5.1.1 (see above)
Expanded vinyl wall
NFPA 286: Meet all requirements listed in IBC
coverings
803.1.1.1 (see above)
ASTM E84/UL 723: Class A and must be protected
with automatic sprinkler system
NFPA 286: Meet all requirements listed in IBC
Expanded vinyl ceiling
803.1.1.1 (see above)
coverings
ASTM E84/UL 723: Class A and must be protected
with automatic sprinkler system
High-density
NFPA 286: Meet all requirements listed in IBC
polyethylene and
803.1.1.1 (see above)
polypropylene
NFPA 286: Meet all requirements listed in IBC
Site-fabricated Stretch
803.1.1.1 (see above)
Systems
ASTM E84/UL 723: Class A, B, or C
NFPA 286: Meet all requirements listed in IBC
Laminated products with
803.1.1.1 (see above)
wood Substrate
ASTM E84/UL 723: Class A, B, or C
NFPA 286: Meet all requirements listed in IBC
Facing or veneer applied
803.1.1.1 (see above)
over Wood substrate
ASTM E84/UL 723: Class A, B, or C
In addition to these requirements, there are specific requirements for individual occupancies. For the PAC,
A-1 occupancy is used since there is no occupancy separation, however the requirements are the same
for A-3 and B occupancies, which are the other two that are present in the building. There is also accessory
S occupancies however the requirements for S occupancies are lower than the others. Where a
requirement specific to the occupancy is greater than the requirements stated above, the more stringent
requirement must be met. The following are the requirements for interior finishes for walls and ceilings
39 | P a g e
tested with ASTM E84/UL 723 (materials that comply with requirements in IBC 803.1.1.1, see above, are
considered Class A) for A-1 occupancies that are sprinklered (IBC Table 803.13):
•
•
•
Interior exit stairways and ramps and exit passageways: Class B
Corridors and enclosure for exit access stairways and ramps: Class B
Rooms and enclosed spaces: Class C
Additionally, interior finish material that are applied to fire-resistance-rated or noncombustible building
elements must meet the requirements of Class A unless they are protected by an automatic sprinkler
system on both sides, are attached to noncombustible backing or furring strips, or where the combustible
void is filled with a noncombustible material (IBC 803.15). There are some other minor requirements for
walls and ceilings finishes that are not likely to apply to this building that can be found in IBC Chapter 8.
The interior floor finish and floor covering materials are also subject to the requirements of IBC Chapter
8. Interior floor finishes and covering materials are tested to ASTM E648 or NFPA 253 and are required to
be not less than Class II rating for assembly, business, and storage occupancies. In addition, floor covering
materials must comply with the requirements of the DOC FF-1 “pill test” or ASTM D2859. Since the
building is equipped with automatic sprinkler’s, materials tested with the DOC FF-1 “pill test” or ASTM
D2859 are permitted where Class II materials are required.
Performance-Based Egress Analysis
The performance-based aspect of this egress analysis is largely based on Chapter 14 of the SFPE Handbook
3rd edition called “Emergency Movement.” For prescriptive design, the movement time of occupants is
indirectly accounted for through the sizing of egress components. However, in performance-based egress
design, the movement and total evacuation time of the occupants is calculated directly. The time that is
calculated for the time it takes for occupants to evacuate a space or building is called the required safe
egress time (RSET). This time is compared to the available safe egress time (ASET) which is the time it
takes for the fire-induced conditions in a space or building to reach the point of untenability. The ASET is
calculated based off of design fires and modeling to determine time to untenability by smoke, heat,
structural stability, etc. The tenability limits for smoke inhalation will be discussed in a later section,
however, the actual ASET will not be calculated as part of this report.
Commonly, the RSET is divided into five categories as follows:
𝑅𝑆𝐸𝑇 = 𝑡𝑑 + 𝑡𝑎 +𝑡𝑜 +𝑡𝑖 + 𝑡𝑒
Where
𝑡𝑑 = time from fire ignition to detection
𝑡𝑎 = time from detection to notification of occupants
𝑡𝑜 = time from notification until occupants decide to take action
𝑡𝑖 = time from decision to take action until evacuation commences
𝑡𝑒 = time from the start of evacuation until it is completed
(source: SFPE HB 3rd edition)
The time from fire ignition to detection depends on the fire size, smoke production, environmental
characteristics, and detection devices. The time from detection to notification depends on the system
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used but should be a short period of time. While these are very important aspects of the RSET calculation,
they are much more related to detection and alarm systems and will not be discussed at length here.
The time it takes for occupants to take action and to begin evacuating is dependent on human behavioral
response. People can be influenced by many factors such as social interactions, environmental conditions,
the built environment, leadership (or lack thereof), and demographics. The two factors that correspond
with the concept of human behavior are 𝑡𝑜 and 𝑡𝑖 and will usually be lumped into one “pre-movement”
time. This will be discussed at length in the next section.
The last component of RSET is 𝑡𝑒 , which is the time for the occupants to evacuate once they have started
moving. This time may be the time for occupants to reach a protected stairwell or the time for occupants
to full exit the building, depending on the circumstance. There have been numerous studies into
movement times for people walking, moving through doors and corridors, and moving up and down stairs.
Pre-Movement Time
Pre-movement time in an emergency is most influenced by human behavior. As Dr. Kuligowski states in
Chapter 58 of the SFPE Handbook (5th edition), “Human behavior in fire is the study of human response,
including people’s awareness, beliefs, attitudes, motivations, decisions, behaviors, and coping strategies
in exposure to fire and other similar emergencies in buildings.” It is important to understand how
occupants will react, because in certain situations the time to get people moving can be less than the time
for them to evacuate. Placing a flat time on pre-movement for all buildings would likely not properly
account for the differences in occupant characteristics and would not end up being a correct estimation.
Since it is so important to occupant safety to maintain that occupants leave a space or building before
untenable conditions are reached, a large emphasis should be placed on trying to correctly calculate the
pre-movement and movement time.
To understand how people will behave in a fire, Dr. Kuligowski states that it is important to understand
how people will likely not behave. Panic used to be a widely accepted theory for how humans will behave
with fire, but it has largely been proven not to be true. For example, in studies and survivor interviews of
the 2001 WTC attack stated that people were overall calm and altruistic, rather than panicking or
competing. Another previously accepted theory to human behavior in fire was disaster shock. Disaster
shock suggests that people will either panic or go into shock and not respond in a fire situation. Again,
multiple studies including those on the WTC found that occupants helped others and took initiative in
their response. Finally, group mind is an oversimplification stating that individuals in a disaster will think
as a group and act together in response to the danger. While people may be influenced by those around
them, they are still making individual decisions.
The Protective Action Decision Model (PADM)
The Protective Action Decision Model (PADM) is based off empirical studies of past hazards and disasters
and can help layout the framework for understanding human behavior in fire. The model states that the
physical and social environment can cause an occupant to perceive threat and act. Whether they act and
how quickly depends on how they perceive the threat. How people perceive a threat can depend on the
pre-event beliefs about the disaster. People may have different beliefs about the likelihood and
seriousness of a fire, which can change how they respond to cues from their surroundings. Additionally,
whether people view those giving directions as trustworthy or unreliable will change their reaction.
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After receiving cues from their surroundings and running through pre-event perceptions, the occupant
will either return to life as usual, or begin the decision-making process. They will likely think and gather
more information about the threat and whether they should respond to it. If they decide there is a credible
threat, they will begin to seek for protection and decide how to best protect themselves with the
resources available. Finally, the individual must decide if the protective actions should take place now or
wait. This decision-making process can be influenced by notifying occupants in the following ways:
•
•
•
•
At a high enough level such that all occupants can hear the alarm or message
With visual cues to aide in perception, and for those with hearing disabilities
Message that is specific, repetitive, consistent, and credible
Addresses the needs of those making decisions: information providing credibility, actions to take,
timeliness, locations of fire, and descriptions of hazard
The PAC helps address some of the aspects of the PADM by providing a voice alarm communication system
and crowd managers. The EVAC system will play a prerecorded message notifying occupant of a hazard
and providing them with directions on how to respond. Then, crowd managers will aide in addressing
occupant questions and concerns, while encouraging calm and effective evacuations. Ideally, these
aspects would reduce the pre-movement time. This will be discussed at length in the next sections.
Factors That Influence Occupant Behavior
Dr. Kuligowski states five main factors that influence occupant’s behavior in a fire: social influence, stress,
the built environment, leadership, and demographics. Social influence in fire generally states that
individuals are influenced by those around them. As stated earlier, this does not mean that every person
in a group will respond the same, but rather that they will take in other’s actions as an additional piece of
information in addition to other cues. Studies have found that occupants may not report a fire if others
around them also do not. If others do not seem to view the fire as an emergency, an individual may be
less likely to perceive threat. In the situation of a theater, this could happen if the performance continues
or the lights do not turn on when there is an emergency. If either of these situations were to happen
people would either not know there was an emergency or would perceive it as a false alarm. On the other
hand, if in the middle of an event the lights came on, alarms went off, and the performance stopped, it
would be hard for an occupant not to perceive a threat.
Another factor that can influence occupant behavior is stress. Stress can be brought on due to the threat
of harm from the fire, but can also be brought on by uncertainty, information overload, and time pressure.
If the occupants receive too little or too much information or may begin to feel there is not enough time
to exit the building. Stress can lead to occupants not making connections between information, making
decisions that are not optimal, or ignoring some information. If a fire were to occur in the large Main Hall
in a visible location, this could cause a significant amount of stress for occupants. Leaving theater seating
is a process that requires patience and trust that other occupants are moving as quickly as possible. If
occupants start to believe that they will not be able to exit in time because people in their row are slow,
they could begin to make rash decisions. On the other hand, there is an opportunity to give very thorough
information to occupants since they are all already in one area focused on one aspect. If proper control is
taken, occupants will be assured that they are being protected and they will stay calm.
The built environment can also influence occupant decision making. Most occupants in the PAC are
unfamiliar with their surroundings. Therefore, they are likely to try to exit in the same manner that they
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came in unless they are influenced by their surroundings. Without influence, occupants may take routes
that are optimal for normal operations but may not be the fastest route out of the building. Since the
building is equipped with crowd managers, they should be utilized to direct occupants towards exits that
are less crowded. Additionally, the use of strobes, exit signs and voice communications should also help
direct occupants in the proper route. The built environment should be utilized to ensure that occupants
will understand that there is a danger and that they should begin evacuating at the direction of crowd
managers. This should help reduce the overall pre-movement time.
Leadership can also help shape how occupants will respond to a fire situation. In buildings where there
are leaders prior to the event, occupants are more likely to take directions from them. In the King’s Cross
Disaster, which was a fire in a transit station, occupants were likely to follow the directions of police
officers even when the directions were confusing or incorrect. By this logic, the introduction of crowd
managers should provide a pre-event leadership. However, the occupants must view the crowd managers
as trustworthy for them to be effective. If the crowd managers are used when filling the building to direct
occupants, they will likely view them as more trustworthy than a crowd manager that only appears once
there is an emergency. If crowd managers fail to keep the crowd directed early in the evacuation, there
are no other pre-event leaders to take over. Therefore, it is pertinent that the crowd managers begin
assisting early in the evacuation to establish leadership. If they do so, the premovement time should stay
low.
Pre-Movement Time
Based on the PADM and the occupant characteristics that affect behavior in an emergency, a premovement time must be decided on. Chapter 64 of the SFPE Handbook provides data from research on
pre-evacuation time for various occupancies. Two studies were done on occupancies like that of the PAC
(cinema and theater). These studies saw a range of 8 to 36 seconds of pre-evacuation time. It is not
unlikely that these pre-movement times could occur if the occupants in the theater are properly notified
and the performance stops immediately. However, there could be some delay in the building going into
alarm and the occupants understanding that there is a threat and moving due to the behavioral factors
addressed earlier. In order to provide a conservative analysis, assume that it takes one minute from the
time the alarm sounds for the performance to stop and lights to come on. Since occupants will probably
not begin moving until these events happen, the pre-movement time should be at least one minute. After
the performance stops and the lights come on, the occupants must recognize where they need to go and
decide to leave. Based on the research data provided in the SFPE Handbook, assume this may take 40
seconds. Therefore, the overall pre-movement time after the fire has been detected and the alarms sound
is 100 seconds.
Movement Time
The movement time is the final part of the ASET calculation. Since the building’s largest portion of
occupants is in the Main Hall area, this calculation will assume that a phased evacuation does not occur,
and the entire building begins evacuating at once. The evacuation time will be considered complete when
every occupant has completely exited the building. The calculation assumes that occupants will equally
utilize all exits that are available to them. When occupants travel through one egress component slower
than the component leading to it, a queue will form. When a queue forms, the occupants are “dosed”
through the door, and it is assumed that they move through the door at the optimal flux rate.
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The first step in calculating egress time is figuring out where occupants will egress.
Figure 23. Pit Level egress distribution.
For the pit level, the occupants in the main area were distributed evenly between the two exits. The
occupants on the left side rooms egress directly to public way and are not considered in the calculation
since their egress will be shorter than at other locations.
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Figure 24. Orchestra level egress distribution.
The orchestra level has one of the more complicated egress distributions. All occupants who used the
three main stairs to exit on other levels will exit the building on this level. The occupants in the main hall
were distributed evenly between the four exits, except the loggia only used the back exits. All occupants
exiting from the main hall are assumed to use the gallery and then exit through the lobby on the next
level. The stage was divided evenly between the five exits, then distributed between the three nearest
exits. The dressing rooms in the back all used the exit that connects to the corridor. The most loaded exit
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on this level is the exit near the classroom as it receives most of the classroom occupants, the rehearsal
pavilion occupants, and some occupants from the stage and upper floors.
Figure 25. Main/lobby level egress distribution.
On the lobby level, most occupants use the main lobby doors to exit. Some occupants go downstairs and
exit on the orchestra level. The lobby has a total of 1026 occupants who egress evenly through the 9 doors
that are available.
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Figure 26. Balcony level egress distribution.
Occupants in the balcony are distributed evenly to the four exits available. Those nearest to the stage use
the top two exits and exit on the orchestra level. Occupants located further from the stage and in the
founder’s lounge use the front stairway and exit on the orchestra level. None of the occupants on this
floor will use the main exits in the lobby as the stairs leading there are not used for egress.
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Figure 27. Gallery (upper balcony) level egress distribution.
On the gallery level, occupants exit similarly to the lower balcony level. The occupants in the balconies
are distributed evenly, with those in the front of the stage using the top stairways. The other half of the
balcony occupants use the bottom stair, and none will exit through the main lobby doors.
It is likely that queueing will occur at multiple locations throughout the building. In order to find the total
evacuation time for the building, the queueing locations must be found and the one that takes the longest
to evacuate will be the total evacuation time. The following locations will be checked for queueing: 3 main
stairs, main lobby doors, and exit door near classroom.
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The three main stairs will be referred to as stairs 1,2, and 3 from this point on as shown below:
The longest queue at Stairs 1&2 will occur on the orchestra level at the exit door. The total time to
evacuate each stair will therefore be the amount of time it takes for the first occupants to reach each door
and the amount of time it will take for the occupants to exit through the door at the orchestra level. For
Stair 1, there are 101 occupants exiting with a 72” door. Accounting for the effective width of the door,
and if the occupants exit at the optimal flux (24 persons/min/foot), it will take 51 seconds for occupants
to exit once they have reached the door. The stairs in this building have a 7-inch rise and 11-inch run, and
there are 12 feet between floors. Based on this, it will take 22 seconds for the first occupants to reach the
stairway door once they have entered the stairs. The occupants on the pit level will reach the stairs after
49 seconds. Adding these three figures, the total evacuation time for Stair 1 is 122 seconds. Similarly, for
Stair 2 the total evacuation time is 130 seconds.
In Stair 3, queueing does not occur at the orchestra level. Instead, queueing occurs at the gallery level.
Here, the door entering the stair is only 30”, with an effective width of 18”. The flowrate through this door
will be 36 occupants per minute which is slower than at the other floors. It will take the furthest occupant
70 seconds to reach the stair door. Based on these figures, it will take 204 seconds for the occupants to
egress through the stairs. Then, they must travel 3 floors, which gives the total evacuation time for Stair
3 to be 270 seconds. This is much longer than the egress times for the other main stairs.
At the exit door near the classroom, queueing will occur. Although there is queuing at other doors leading
to this exit, there are 4 egress paths with large loads that all lead to this door, causing the longest queue
there. This door is 66” clear width, which gives a 54” effective width available for egress. Using the optimal
flux rate through this door, the flow rate will be 108 occupants per a minute. A total of 826 occupants use
this door, so it will take 459 seconds for all occupants to exit the door. The queue will begin after occupants
from the rehearsal pavilion and classroom begin to exit, and the travel time for the occupants to begin
queueing is 18 seconds. Therefore, the total egress time through the door near the classroom is 477
seconds.
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Finally, queueing may occur at the main lobby exit doors. It will take 71 seconds for occupants from the
dress circle to reach the exit doors. The doors each have a clear width of 60” with corresponds to an
effective width of 48” and a flow rate of 96 occupants per minute. There are only 133 occupants coming
from the dress circle, so they will not cause queueing on their own. Factoring in the occupants who came
from the main hall, they will take 104 seconds to reach the doors. Since the total flow for the nine doors
is 864 occupants per a minute, the occupants will be able to exit through the doors before a queue occurs.
Without a queue, these occupants will be able to exit much faster than the occupants at the door near
the classroom, so the calculation was halted.
There were quite a few assumptions that went in to calculating the evacuation movement times. First, it
is assumed that all occupants begin evacuating at the same time. This assumption is worked mainly into
the aspects of travel time to doors and queueing/load at doors. If everyone is assumed to move at the
same time, the time for the furthest occupant to reach the door is simplified to only the time it takes them
to walk and does not consider that another occupant may take longer if they wait longer to start moving.
Next, it is assumed that occupants don’t influence other’s decisions and ability to egress. This would
remove the possibility of a group not exiting because of social influence and that an occupant will not turn
around to go back for something or to help others. These remove variables from travel times and flow
rates through doors that would complicate the calculation significantly. Another rather large assumption
is that people will move through doors at the optimal flow rate as specified in the SFPE Handbook.
Although an individual will move through a door or stair faster on their own, the flux of the flow is much
higher when there is queueing. This makes some sense because the door will be used to its maximum
capacity at any point in time even though individuals may have to wait longer in a queue. There is truth
to this assumption, however studies have found that the flow rates that are commonly used are higher
than what has been found in actual egress studies. Finally, the calculations assume that no stairs or doors
are blocked by a fire and that occupants use the exits equally. These assumptions can be true in some
cases, but it has been found that people are more likely to use an exit that they are familiar with.
Additionally, if a fire blocks any exit, the density of the occupants could exceed the optimal density and
cause flow fluxes to decrease since it is too crowded for people to move. Overall, these assumptions work
out to probably not providing a conservative approximation. There is a likelihood that at least one
assumption will not be true causing some of the following effects: occupants observe others not leaving
and decide to wait, occupants behave altruistically and go back to help others, occupants move through
doors and stairs slower than optimal flux, or a stair is blocked causing occupants to circle back or
overcrowd one exit. Therefore, in order to produce a conservative analysis, a margin of error or a safety
factor should be added. With such large assumptions, a safety factor of 1.5 to 2 would probably be
appropriate.
After checking all the egress options for queueing, it was found that the longest exit time occurs at the
door near the classroom with a total egress time of 477 seconds. This figure is used for the total movement
time and added to the earlier decided pre-movement time. However, there are a quite a few assumptions
that went into calculating the movement time as discussed above, so a safety factor of 1.5 is added to the
movement time. This brings the movement time to 716 seconds and the pre-movement time to 100
seconds. The entire building will then be evacuated in just under 12 minutes.
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Tenability Analysis Criteria
As discussed earlier, the available safe egress time must be compared to the required safe egress time to
determine whether occupants will be able to exit the building safety. Tenability determines the available
egress time. While there are a few factors that can lead to untenable conditions, smoke inhalation is one
of the main causes of untenability. Smoke can cause two types of damage to occupants: irritation and
asphyxiation. Smoke products such as HCl, HBr, and HF (acid gases) cause occupants’ irritation while CO
and HCN can cause asphyxiations. Additionally, elevated levels of carbon dioxide can increase the uptake
of air and speed the process of asphyxiation from CO and HCN. Since asphyxiants cause the most direct
harm to occupants in most fire situations, they will be addressed here.
The concept that is usually used to calculate harm to occupants due to smoke products is the fractional
effective dose (FED). The FED is the dose received at time compared to the dose that will cause
incapacitation or death. Substances like carbon monoxide have a linear uptake of the toxic substance,
meaning that the amount of the toxic substance that is received at any point in time does not depend on
the amount of toxin already in the body. For HCN, however, the uptake is not linear, and the toxin will be
taken in slower once the body already has high levels of the toxin. This concept is shown below in the
figure.
Figure 28. Incapacitation by CO (left) is constant while HCN (right) decreases with uptake.
In the left graph, if the ppm of CO is multiplied by the corresponding time to incapacitation, the value will
stay approximately constant. However, as seen in the graph on the right, the HCN concentration
multiplied by the time to incapacitation is not constant. When calculating the FED of CO, the dose to cause
incapacitation or death will remain constant while the HCN FED will change as time goes on.
Carbon monoxide toxicity can be represented by either the parts per million in the air or by the %COHb
in the blood. The following equation can be used to convert from CO levels to %COHb:
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This equation applies to a constant CO level but can be integrated to account for the CO level increasing
or decreasing over time.
The FED model assumes that CO and HCN are additive in their effects. Additionally, since carbon dioxide
is present in all fires, it is added to the model by increasing the breathing rates of occupants as the oxygen
levels in the space decrease. Irritancy is independent from asphyxiation but can be calculated in a similar
method. The equation used for FED is shown below from the SFPE Handbook:
In order to solve the FED model, appropriate values for the ventilation rate (breathing rate) and the
exposure dose for incapacitation (or death) from asphyxiants and irritants. Since most fires don’t have
large amounts of acid gases produced, the lethal does for irritants is calculated using optical density which
will be solved during the design fire stage.
The ventilation rate is mostly dependent on how the occupant is moving. For occupants moving
downstairs or walking, a typical ventilation rate is 25 L/min per the SFPE Handbook. For occupants moving
upstairs or running, the ventilation rate is 50 L/min. The ventilation rate of a subject at rest is usually used
to calculate the time to death from smoke inhalation. After an occupant becomes incapacitated, they will
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stop moving which will cause their breathing rate to decrease to that of a subject at rest, which is about
8.5 L/min.
The exposure dose for carbon monoxide is also dependent on how the occupant is moving. For occupants
that are moving more, not only will they breathe in more carbon monoxide, they will also be incapacitated
or die at a lower carbon monoxide level in their blood. For occupants doing light work, they will be
incapacitated at 30%COHb, based on values provided by the SFPE Handbook Chapter 63. When death
occurs, occupants will have likely already been incapacitated, so the value used for death is 50% COHb.
The exposure dose for HCl and irritants are provided in the SFPE Handbook in Table 63.7, which can be
seen below.
Table 18. (SFPE HB Table 63.7) Exposure doses for incapacitation and lethal lung damage.
The AEGL values provide a much more conservative calculation than the SFPE values and therefore should
be used for this calculation.
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