Field Burnout Tests of

Apartment Dwelling Units

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UNITED STATES DEPARTMENT OF COMMERCE • Alexander B. Trowbridge, Secretary

NATIONAL BUREAU OF STANDARDS • A. V. Astir,, Director

Field Burnout Tests

of Apartment Dwelling Units

D. Gross

Building Research Division

Institute for Applied Technology

National Bureau of Standards Washington, D. C.

Building Science Series 10

Issued September 29, 1967

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C., 20402 - Price 25 cents
Contents

Page

1. Introduction 1

2. Objectives 2

3. Description of test building 2

4. Test Plan 4

5. Test results 6

5.1. Test log 6

5.2. Moisture 7

5.3. Temperatures 8

5.4. Radiation 11

5.5. Smoke 11

5.6. Toxic combustion products 12

5.7. Deflection 12

6. Discussion 13

6.1. Burnout tests 13

6.2. Fire intensity 14

6.3. Radiation 15

6.4. Smoke 16

6.5. Toxic combustion products 16

6.6. Structural effects 17

6.7. Potential heat 18

7. Summary 20

8. References 21

9. Appendix 21
Field Burnout Tests of

Apartment Dwelling Units

D. Gross

Results are reported of three burnout tests in an experimental test building, using a wood crib fuel load of 6 lb/ft', representing combustible contents, and a structural design load of 40 lb/ft" applied to the floor or roof above the test room. Measurements

were made of temperature, radiation, smoke, gas composition, and structural deflection. A discussion of the fire performance of materials and methods of construction, and

conclusions with regard to specific fire-protective objectives are presented.

Key words: Burnout test, fire performance, apartment dwelling, smoke, flame penetration, structural load, potential heat, fire load.

1. Introduction

The conventional method for evaluating the

fire performance of large-scale structural building components such as walls, columns, floors,

etc., is by means of a standardized laboratory

fire endurance test [1]'. The essence of the

laboratory test is the application of heat to provide a specified and closely controlled increase

in temperature to the structural component in a specially-designed furnace. The results are reported in terms of the time period during

which the structure resists the fire exposure

without the occurrence of one of several failure

criteria. Other standardized laboratory tests are employed for evaluating surface flame

spread, heat production, combustibility, and

smoke.

Such laboratory tests permit comparative

evaluation of the individual components of a

building, and thus provide the means for estabhshing building code requirements in terms of

performance standards. Additional research,

both in the laboratory and in the field, has been

directed toward an understanding of the factors

which govern the growth and severity of accidental or unwanted fires, so that the fire endurance periods required of building components

may be related to the expected fire severity

which could occur in the building.

Field studies of the growth of experimental

fires in buildings have usually been conducted

on and within structures destined for demoli-

' Figures in brackets indicate the literature references on page 1.

tion. Although such buildings may still be in good structural condition, they are not generally representative of current building practices and architectural innovations. This paper

describes a field study conducted on a "new"

test structure specifically designed and built as a vehicle for a variety of construction, sound

transmission and fire tests. In this way, field evaluation could be accomplished on the integrated construction, rather than on components

or individual assemblies.

The overall program was developed by the

Research Department of the School of Architecture of Pratt Institute as part of its work

under a Low Income Housing Demonstration

grant from the U. S. Housing and Home Fi- nance Agency. The primary objective of the

Pratt Institute study was to demonstrate that

significant reductions could be achieved in the

cost of high-rise housing by the use of new

materials and advanced methods of construction. While this demonstration is to be accomplished in an actual high-rise building to be

erected subsequently, information on construction details, on sound transmission, and on the

fire-protective features of candidate constructions was to be obtained by means of field studies on a second, or test building, specially

designed and erected by Pratt Institute. The

Fire Research Section, National Bureau of

Standards, undertook the responsibility for the

planning and the conduct of full-scale burnout

tests in the test building.

1
2. Objectives

With respect to fire protection, the primary

aims of Pratt Institute were the protection of

the occupants and the prevention of fire spread

to other apartments and buildings. The protection of the building itself or of property within

it was not a primary aim.

In the test building, structural and planning

features were incorporated with the aim of

accomplishing the following specific objectives:

1. Confinement of fire and smoke within the

dwelling unit or other space in which the fire starts.

2. Protection of the building structure

against failure to carry load.

3. Use of minimum quantities of combustible construction materials.

To the extent possible, the burnout tests were

designed to obtain information on the degree to which these objectives could be accomplished.

Pratt Institute established additional fire re- sistance requirements [2], conformance to which was outside the scope of the burnout

tests. The following tentative requirements,

based on performance during the standard fire endurance test [1], were established by Pratt

Institute

:

3. Description

The test building was located in Carteret,

N. J., and consisted of two two-story wings

connected by a wood platform and stairs (see

fig. 1). One wing was of steel frame construction with exposed exterior columns and dry

floor construction; the other was of precast concrete, bearing wall construction. Each wing

Requirement

Component

Fire Endurance [1] Noncombustible [3]

Structural—columns,

bearing wall, girders,

floor slabs, beams

Thermal

i^hr

Structural

1 hr

Exterior non-bearing walls Noncombustible,

if 30 ft or more

from another

building

Partitions between adjacent dwelling units; Partitions between

dwelling units and

public or service areas

Thermal

Vi hr

Partitions within dwelling

unit; Closet shelving and

kitchen cabinets

Noncombustible

Tenant storage area Thermal 1 hr

Test Building

contained three rooms per story: two rooms,

each about the size of a small bedroom, and the

third representing a room of an adjacent apartment. The latter room contained a half-bath

and an entrance to an outside balcony. The steel wing was approximately 12 by 34 ft in outside

dimensions (balcony not included) with floor

Figure 1. Test building viewed from southwest.
area per room ranging from 114 to 134 sq ft; the concrete wing was approximately 14 by 32

ft outside with floor area per room ranging

from 100 to 123 sq ft. Ceiling height was 8 ft. Three types of curtain wall construction, two

types of party walls (between apartments) , two

types of floating floor construction, and innovations in plumbing and heating were incorporated in the test building. Additional details of

the test building construction are supplied else- where [4].

Erection of the steel wing was started in May,

the concrete wing in June, with the entire in- terior fiinishing completed by mid-July. Following acoustical tests of sound transmission

through walls and floors in early August, burnout tests were conducted in the steel wing on August 24th, and in the concrete wing on September 1 and November 3, 1965.

4. Test Plan

Figure 2 is a plan view of the test building

showing the arrangement of instrumentation

I for the first two burnout tests. The third test

i was similarly, but less completely, instrumented. During each test, a photographic recj ord and visual observations were made and

I measurements were also made of temperature,

j radiation, smoke, gas composition, and struci tural deflection. However, because of staff and

' budgetary limitations, and the fact that the

i test site was located 200 miles from the laboI ratory, certain measurements were limited in

I scope, while others, e.g., ventilation eff'ects, were not considered feasible.

I For Test No. 1, a fire load of 6 Ib/ft^ of floor

I area was placed in room 1-6 of the steel wing.

The same fire load was placed in rooms 1-3 and

! 2-3 of the concrete wing for Test No. 2 and

8WF 31 Coloi Figure 2. Instrumentation arrangement—schematic.

All doors and windows closed during test except for window in lire room, which was partially open.

Test No. 3, respectively. The fire load consisted

of nominal 2- by 4-in dry Douglas fir lumber

nailed into lattice-type cribs (see fig. 3). The

cribs were supported 16 inches above the floor

and were ignited by means of a flammable

liquid (6 or 10 qt of normal heptane) placed in

pans beneath the wood cribs. The overall dimensions of the aluminum sliding windows were 4

ft by 5 ft 5 in (21.7 sq ft) in the steel wing and

4 ft by 4ft Sin (17.7 sq ft) in the concrete wing.

The initial window openings (11 in wide by 60

in high for room 1-6, and 14 in wide by 50 in

high for rooms 1-3 and 2-3) were chosen to limit the maximum burning rate and to extend

the burning period beyond 30 min, if possible,

but no effort was made to prevent the breakage

and fallout of glass due to the effects of fire. All other doors and windows were closed during test. No combustible material was placed in

the adjoining rooms. For Tests 1 and 2, the three second-floor rooms (except bathroom) were loaded to the

40 lb/ft= design load using concrete block set on end. For Test 3, the 20-ft long roof slab

24 M

1 ^ 1 ^ 1 1 1 \^

3 6" -

NO. OF LAYERS

1314

14

APPROX. WEIGHT, I b EACH CRIB TOTAL (6 CRIBS)

137 148 148

685 740 740

^=iy t=iy \ Figure 3. Construction of wood crib.

3
above the fire test apartment was similarly

loaded.

Photographic coverage included 16 mm color

movies from several locations, 16 mm color

Table 1. Location of thermocouples

Ther- Ther- mocou- Location mocou- Location

ple No. ple No.

Test No. 1

1 Room air NE 21 Exterior column 11 2 Room air NW ft outer

3 Room air SE 22 Exterior column 11 4 Room air SW ft inner

5 10-in. girder SE 23 Exterior column 14 6 10-in. girder NE ft outer

7 South joist E 24 Exterior column 14 8 South joist center ft inner

9 South joist W 25 Room 2-6 floor NE

10 North joist E 26 Room 2-6 floor NW

11 North joist center 27 Room 2-6 floor SE

12 North joist W 28 Room 2-6 floor SW

13 South i2-in. 29 Exterior (cone)

beam E wall, center

14 South 12-in. 30 Room 1-8 wall, beam W center

15 North 12-in. 31 Room 1-8 wall, N,

beam E top

16 North 12-in. 32 Room 1-8 wall, N,

beam W bottom

17 Exterior column 5 33 Room 1-5 wall, N,

ft outer top

18 Exterior column 5 34 Room 1-5 wall, N,

ft inner bottom

19 Exterior column 8 35 Room 1-5 wall,

ft outer center 20 Exterior column 8 36 Room 1-5 door.

ft inner center

Test No. 2

1 Room air NE 24 Reinforcing wire

2 Room air NW level N

3 Room air SE 25 Room 2-3 floor NE

4 Room air SW 26 Room 2-3 floor NW

5 Steel angle S 27 Room 2-3 floor SE

6 Steel angle S 28 Room 2-3 floor SW

78Steel angle N

Steel angle N

29 Room 1-1 wall, S, top

9 Reinforcing wire

level E

30 Room 1-1 wall, S, bottom

10 Reinforcing wire

level E

31 Room 1-1 wall, center

12 Room 1-4 air 32 Room 1-4 wall, 13 Room 1-3 floor center. 17 Reinforcing wire

level S

33 Room 1-4 wall, S, top

18 Reinforcing wire

level S

34 Room 1-4 wall, S, bottom

19 Reinforcing wire

level center 35 Room 1-4 door, center 20 Reinforcing wire

level center 36 Exterior (S'wich)

wall, center 21 Reinforcing wire 37 No. 3 bar, grout

level center joint, W

22 Reinforcing wire

level N

40 No. 3 bar, grout

joint, N, center 23 Reinforcing wire 41 Steel strap N, center

level N 42 Steel strap NE

Table 1. Location of thermocouples—Continued

Ther- mocou- Location mocou- Location

pleNo. ple No.

Test No. 3

44 Room air NE 48 Room 2-1 wall, 45 Room air NW center 42 Room air SE 49 Room 2-1 wall, air 41 Room air SW 50 Room 2-4 door, 46 Room air NW center (ASTM-type) 51 Room 2-4 wall. 43 Room air SE center (ASTM-type) 52 Room 2-4 air 47 Reinforcing wire 53 Exterior (S'wich)

level, ceiling panel

center 54 Fire room, 1 ft, bare thermocouple

time-lapse movies from a fixed location and 35 j mm color transparencies.

Temperature measurements were made using

thermocouples placed in the test room, on or near structural elements and on "unexposed"

wall and floor surfaces of the adjacent rooms, i The location of thermocouples is shown in fig- ures 4 and 5, and listed in table 1. Air tempera- j ture in each adjoining room was measured by

a single mercury-in-glass thermometer or a 5 single thermocouple placed 5 ft above floor . level. Except for fire room air thermocouples, , all thermocouples were of No. 24 B&S gage

Floor Areo 11411^ Window Area 2l.7ft^

Figure 4. Location of thermocouphs, Test No. 1. I • —on structural element; o—on interior wall surface; A—on exterior I wall surface.

4
Floor Area 123 ft^ Window Areo iT.Tft^

Figure 5. Location of thermocouples, Test No. 2. Chromel and Alumel wires, the welded beads

of which were mechanically fastened into predrilled holes in steel or concrete, or were placed

under asbestos pads on "unexposed" surfaces.

Four commercial 18-gage Chromel-Alumel

thermocouples of the extruded metal-sheath,

ceramic-insulated type with fast response times

(less than 5 sec to 63.2 percent of step temperature change) were used to measure air temperature in the fire room in all tests. Fast response

thermocouples give a more accurate measure of

transient air temperatures compared to thermocouples placed in heavy pipes either for protective purposes or for minimizing the recorded

temperature oscillations in standard fire endurance tests. In Test No. 3, two 18-gage Chromel

and Alumel wire thermocouples mounted within

porcelain insulators in steel pipes (ASTM-type

[1] ) were added for comparison purposes.

Radiometers were placed as shown in figure

2 with the objective of measuring irradiance

levels and permitting estimates to be made of

distances at which the spread of fire by radiation might occur through doors and windows,

and between buildings. Irradiance levels were

measured with a wide-angle single thermocouple disk radiometer [5] and with a wideangle 10-j unction thermopile radiometer. A

commercial, narrow-angle total radiation pyrometer was used to measure the apparent

blackbody temperature of the flaming interior

of the fire room. Smoke accumulation in rooms adjacent to or above the fire room was monitored by measuring the attenuation of a light beam (see fig. 2)

.

The light source, consisting of a 30-W lamp,

and the light detector, a type 1P39 vacuum

phototube and battery, were assembled in a

single box placed on the floor. Using a mirror

flush-mounted on the ceiling, a double vertical

light path was obtained, extending from 1 ft above the floor to the ceiling. This reduced

errors in total smoke measurement due to stratification effects. The optical system was planned

to exclude, as much as possible, all light not

originating from the 30-W lamp source. As

noted later, this was only partially achieved.

Indications were obtained of certain toxic

combustion products in rooms adjacent to the

fire room by means of direct reading colorimetric gas detecting tubes [6]. Using a manuallyoperated hand pump, a sample of the gas to be

analyzed was drawn through the previously

sealed detector tube where a chemical reaction

occurred and gas concentration was indicated

either by a color change or by a pre-calibrated

length of stain. A separate tube was used to indicate the volumetric concentration of each

particular component of interest. Measurements were made of CO, CO2, HCl and HCN at a few selected locations indicated in figure 2. Measurements were made of the deflection of

the floor (or roof) above the fire room, both at the center of the room and near the partition

at the approximate mid-span of the floor or

roof system. In tests 1 and 2, invar wires were

fastened to the surface of the finished floor

above and passed upwards around pulleys

mounted on the unloaded, relatively cool ceiling

directly above the measuring points. The wires were then passed horizontally near the ceiling

through a hole in the exterior wall to pulleys

mounted entirely free of the building under

test. Each wire passed downward and terminated with a weight to maintain wire tension.

An indicating marker on each wire was used

to follow the deflection changes on a graduated

scale mounted behind the wire. In Test 3, a wooden boom, unsupported by the test building, was installed in order to mount the pulleys

above the measuring points. A few measure- ments were also made of the lateral movement

of exterior wall panels. In Test 1, the invar

wire was fastened to the interior face of the

light-aggregate concrete panel and passed to Cand through) the opposite wall just above the

finished surface of the second floor. In Test 3,

the invar wire was fastened to the exterior

aluminum face of the polystyrene-core sandwich panel. In Test 2, lateral movements of the

north (concrete) wall and the concrete floor slab were made using dial gages. An invar wire was also fastened to the concrete party wall at the second-floor level to indicate longitudinal

expansion of the 20 -ft floor slab.

5
5. Test Results

5.1. Test Log

The following is an abbreviated log of visual

test observations and measurements for each

test. Detailed test observations as well as posttest investigation notes are given in the Appendix. Figures 6, 7 and 8 are photographs taken

during the active burning stages of each test. Test No. 1—Room 1-6, Steel Wing,

August 2k, 1965

Time

(min) Summary Observations

0 Test started at 11:22 a.m. Weather: Clear; Temperature: 74° F; rh 56%. Wind 7 mi/h,

Direction: 30° (NE) (Newark Airport Weather

Eeport)

5 Heavy smoke in Room 1-5. 15 Windows in fire room fell out. Flashover (complete involvement of room in flames). 16 Part of east partition wall fell into fire. 22-23 (Wallboard ceiling fell off; joists and beams

exposed)"

25 Part of west partition wall fell into fire. 35 Fuel supply essentially consumed.

Test No. 2—Room 1-3, Concrete Wing,

September 1, 1965

Time

(min) Summary Observations

0 Test started at 11:23 a.m. Weather: Partly

cloudy; Temperature: 74° F; rh 69%. Wind 14 mi/h, Direction: 180-200° (S).

' Not observed until later. Inferred from temperature recordings.

7 Section of upper right glass pane (% ft^) fell out. 8 Smoke at ceiling, Room 1-4. 9 Only one crib burning.

30 Upper two-thirds of right window pane fell out. 41 Window blown out by explosive concrete spalling; heavy black smoke; fire building up. 44 Flashover; flames out of window.

41-70 Intermittent violent spalling. 40-80 Development and enlargement of cracks in concrete walls, particularly at joints; water weeping from concrete walls; smoke and steam through cracks. 70 Decreased flaming; heavy smoke upstairs,

Room 2-3.

Test No. 3—Room 2-3, Concrete Wing,

November 3, 1965

Time

(min) Summary Observations

0 Test started at 9:55 a.m. Weather: Clear; Temperature: 46° F; rh 68%; Wind: 11 mi/h,

Direction 220° (SW)

3 Section of window glass (l^^ ft') fell out. 4 Section of window glass ( Vz ft') fell out. 10 Bowing of aluminum sandwich panel and alu- minum window frame.

20 Drops of boiling plastic expelled. 28 Remainder of window glass fell out. 31 Concrete spalling. 33 Sandwich panel fell out; room completely in- volved in flames. 45 Fuel supply exhausted.

45-150 Progressive smoldering and occasional flaming

in sandwich panel with slow fire propagation

to Room 2-4.

FlGtTRE 6. Active burning stage, T-est No. 1, approximately 26 min

after ignition.

Windows fell out at 15 min. Note radiometers in position.

6
Figure 7. Active burning stage, Test No. 2, 53 min after ignition.

Windows fell out at 41 min. Observer at left is making gas concentration measurement.

Figure 8. Active burning stage, Test No. 3, 38 min after ignition. Sandwich panel fell out at 33 min. Note concrete block load on roof.

5.2. Moisture

The relative humidity in fire rooms 1-6 (Test

1) and 1-3 (Test 2) averaged 65 percent during the 7-day period prior to test. The moisture content of the wood comprising

the cribs was 10 to 12 percent, as measured

with a prong-type electrical resistance moisture

meter.

Measurements were made of the relative

humidity of air in cavities within the second

floor hollow-core concrete floor slabs and of the

load-bearing partition wall one week prior to Test 2 with the following results:

Hollow-core floor slab, in web between cores, 73 percent rh

Hollow-core floor slab, near grout joint,

82 percent rh

Solid partition.

7
84 percent rh

These measurements are estimated to be within

2 percent of the values assumed in the cahbration of the humidity probe.

Direct moisture content measurements of

the concrete by extracting cores were at- tempted but did not prove successful.

5.3. Temperatures

Test No. 1 Selected temperatures recorded during Test 1 are shown in figure 9. The mean temperature

in the fire room rose steadily until shortly after

15 min when flashover occurred, causing a further sharp increase. Air temperatures re- mained near 1830 °F from 18 to 32 min and

then dropped off. The maximum temperature

reading of an individual thermocouple was

2130 °F. The furnace time-temperature curve

prescribed in the standard laboratory fire test [1] is included for comparison. In any comparison, however, it should be borne in mind

that the latter test prescribes slow-response

thermocouples (mounted in heavy protective

iron pipes) compared to the faster response

thermocouples actually used.

Also shown in figure 9 are average or representative temperature curves for the 12-in

beam, the 10-in girder, the lower chord of the

joist, and the exterior unprotected column at a height of 8 ft above the room floor. Temperatures on the interior structural members were

rapidly elevated from about 212 °F to about

1470 °F when the gypsum board ceiling rapidly

and completely dropped at 221/2 i^in- Temperature measurements were made on the inner and

outer flanges of the exterior column at heights

of 5, 8, 11 and 14 ft above the floor of the fire

room. The temperature was highest at the 8-ft

height and lowest at the 14-ft height. The outer

flange was generally, but not always, hotter

than the inner flange due to the pattern of flow

of flames and hot gases on the column. A maximum temperature of 968 °F at 30 min was

recorded on the outer flange at a height of 8 ft. Temperatures in excess of 825 °F were re- corded over appreciable areas of the column,

corresponding to vertical distances of approximately 4 ft on the outer flange, 5 ft on the inner

flange and 3 ft on the web. Some portions were

exposed to this temperature for 15 min.

The prescribed temperature criterion for

failure in ASTM E-119 is an average temperature rise of 250 deg F under an asbestos pad

on the "unexposed" surface of a test wall or

floor construction. This is based upon the at- tainment of a surface temperature, approximately 320 °F, at which some combustible

materials, when in contact with the wall or

floor, may begin to undergo progressive thermal

decomposition leading to eventual ignition. This

temperature rise was used as one means for

evaluating the thermal performance of components during the burnout tests. The temperature of the exterior face of the

light-aggregate concrete panel under an asbestos pad reached a maximum of 176 °F at 90

min. The temperature at the center of the '' un- exposed" surface of the composite wall adjoining Room 1-5 attained a maximum of 238 °F at 105 min. A temperature rise of 250 deg F was

reached beneath the thermocouple pad on the

back surface of the connecting steel door between Rooms 1-5 and 1-6 at approximately 10

min. After 35 min, this temperature was within

70 deg F of the air in the fire room. The air

temperature at the measuring location in Room

1200

2000 -

40 50 TIME , min

Figure 9. Selected temperatures, Test No. 1.

8
1-5 reached 150 ° F at 26 min and a maximum

of 235 °F at 41 min. The temperature at the

center of the "unexposed" composite wall sur- face of the adjoining apartment (Room 1-8)

reached 156 °F at 2i/4 hr and was still rising

slowly. The air temperature at the measuring

location in the adjoining apartment reached a maximum of 108 °F after 31 min. The temperature on the finished floor (under thermocouple

pads) of the room above the fire rose slowly to a maximum temperature of 170 °F at 85 min.

Test No. 2 As noted in the test log, only one of the cribs

comprising the fire load remained burning after

9 min. The failure of all cribs to ignite simultaneously prevented the rapid and uniform

buildup in temperature in the fire room. As

shown in figure 10, the temperature measured

by the NE thermocouple, situated above the

burning crib, was considerably above the aver- age of the three other thermocouples until after

41 min when complete window dropout and in- tense burning occurred. Because of the cooling

effect of the southerly wind and fire room

temperatures only slightly above the melting

point of aluminum (1220 °F), the aluminum

sandwich panel remained in place. The temperature on the exterior face of the aluminum

sandwich panel under an asbestos pad reached

a maximum of 770 °F at 55 min.

The temperature in the second floor slab

above the fire at the level of the lower reinforcing wires is shown by a typical curve in

figure 10. The maximum temperatures at six

locations varied from 635 to 716 °F and oc- curred at approximately 80 min. At two other

locations, temperatures remained at 212 °F for

extended periods, presumably due to moisture

evaporation endotherms, and the maximum

temperatures reached were 260 and 365 °F.

A typical curve of temperature on the steel supporting angles is also shown in figure 10. At

these east and west wall-ceiling joints, the migration (presumably through the hollow cores)

and subsequent condensation of moisture, probably held the temperature at the steam point

for extended periods. The maximum temperatures recorded on the steel angles ranged from

280 to 341 °F at about 100 min. In the grout

joint along the north wall, a temperature of

about 445 °F was measured during the period

of 70 to 140 min.

The temperature at the center of the "unexposed" surface of the gypsum board partition

between rooms reached a maximum of 206 °F

at 120 min. A temperature rise of 250 deg F

was reached on the connecting steel door at approximately 15 min. The air at one location

in the adjoining Room 1-4 reached a temperature of 150 °F at 42 min, and a maximum temperature of 205 °F at 72 min. The temperature

of the "unexposed" surface of the concrete

partition to the adjoining apartment reached

a maximum of 176 °F after 170 min. The air

temperature at the measuring location in the

adjoining apartment did not exceed 90 °F. The

temperature on the finished floor (under thermocouple pads) of Room 2-3, above the fire, rose slowly and had reached 150 °F when

measurements were discontinued after 5i/^ hr. Test No. 3 Air temperatures measured in the fire room

were intermediate to those measured in Tests

1 and 2, and slightly below the standard fire curve until 35 min. As shown in figure 11, room

air temperature dropped rapidly when the aluminum sandwich panel wall fell out. A comparison between the temperature reUJ 1200

(E< 1000

STO. FIRE ASTM E-II9

(SLOW RESPONSE

THERMOCOUPLES)

.MEAN AIR_

FIRE ROOM

FAST RESPONSE THERMOCOUPLES

NW.SE.SW AVJ -EXTERIOR WALL

1200

1000

800

600

— REINFORCING WIRE LEVEL — —STEEL ANBLE

1 1 1 30 40 50 TIME, min Figure 10. Selected temperatures, Test No. 2.

9
0 10 20 30 40 50 60 70 80

TIME, min Figure 11. Selected temperatures, Test No. 3.

corded by a fast-response thermocouple and an ASTM E-119-type thermocouple is also shown.

The thermocouple within the heavy steel pipe was in close proximity to a fast-response thermocouple whose temperature was in good agreement with the overall average. It is evident

that, during a rapid buildup of temperature, a fast-response thermocouple may indicate temperatures 200 to 400 deg F higher than those

indicated by the ASTM E-119-type thermocouple.

The temperature on the exterior face of the

aluminum sandwich panel rose steadily to 840

°F at 30 min and then rapidly to a peak reading of 1380 °F immediately prior to panel fall- out at 33 min.

Moisture evaporation appeared to limit the

temperature in the roof slab at the level of the

lower reinforcing wires to 212 °F for approximately 40 min, and the maximum temperature

reached was 437 °F at 75 min.

The maximum temperature rise at the center

of the "unexposed" surface of the gypsum

board partition came within a few degrees of

the ASTM prescribed Hmit (250 deg F) at about 75 min. This limit was reached on the

connecting steel door at approximately 71/9 main,

and after 38 min, the door provided very little resistance to the flow of heat from the fire room. At the measuring location, the air in the

adjoining room reached a temperature of 150

°F at 31 min, a temperature of 194 °F at 49

min, and a maximum temperature of 230 °F at 101 min.

The temperature at the center of the "unexposed" surface of the concrete partition to the

Table 2. Selected temperatures and times

Test

Maximum partition temperature

and corresponding time Time to 250 deg

F temp,

rise on

door

Time to 150 F.

air temp,

in adjoining room

Maximum air temperature and

corresponding time

Adjoining room Adjoining apt. Adjoining room Adjoining apt.

Temp. Time Temp. Time Temp. Time Temp. Time

° F min ° F min min min ° F min ° F min

1 238 105 >156 >150 10 26 235 41 108 31

2 206 120 176 170 15 42 205 72 84+ 78 +

3 290 75 156 90 71^ 31 230 101 86 160

10
adjoining apartment reached a maximum of

156 °F at 90 min. The air temperature at the

measuring location in the adjoining apartment

did not exceed 90 °F.

In table 2, a summary is presented of appropriate values of temperature, temperature rise

and time for the three tests.

5.4. Radiation

Two types of radiation instruments were

placed at a selected distance from the fire room

window; a wide-angle thermopile radiometer to measure the irradiance level (often called radiation intensity), and a narrow-angle radiation

pyrometer to measure the apparent blackbody

temperature of a portion of the flames within

the room. Blackbody temperatures bet'-veen 1450 °F

and 1850 °F and averaging approximately 1650

°F, were recorded in Test 1 during the time

period 15 to 35 min. This blackbody temperature corresponds to an actual (thermocouple)

temperature of approximately 1830 °F during

the same interval, and indicates a flame emissivity of about 0.7. In Test 3, a maximum blackbody temperature of 1690 °F was recorded during the relatively brief period of peak flaming.

Blackbody temperature and irradiance level measurements during active flaming were not

obtained for Test 2. To permit a comparison of irradiance levels between tests to be made, the maximum irradi- ance values were divided by the configuration

factor F, normally used in radiant energy cal- culations based on the window openings only, in

the manner suggested in reference [7]. These

hypothetical window I'adiation intensity values, as well as those based on blackbody temperatures, are listed in table 3. Radiation levels at other points may be predicted by multiplying

the hypothetical window radiation intensities

by the configuration factor appropriate for the

window area and point in question.

Table 3. Maximum radiation levels

Fire room Fire room window Room above

(or roof) Exterior door

Measured

blackbody

temperature

Equivalent

radiation

intensity

Measured

irradiance /

Configuration factor FHypothetical

window

radiation I/F

Measured

irradiance Measuredirradiance

Test No. 1 1650

1690

Btu/Sf^ sec 9.4

10.1

Btu/ffi sec 3.0

0.22

0.148

0.0224

Btu/ffi sec 20

9.8

Btu/ft^ sec >1.2

0.15

Btu/ff^ sec 0.84

Test No. 3 0.32

For Test 1, the hypothetical window radiation intensity was approximately 20 Btu/ft- sec compared to an intensity of 9.4 Btu/ft- sec cor- responding to the measured blackbody temperature. This means that radiation from flames

above and surrounding the window in Test 1 contributed as much as that directly from the

window opening. For Test 3, the hypothetical

window radiation intensity was 9.8 Btu/ft- sec

just prior to fallout of the aluminum sandwich

partition.

Also listed in the table are maximum irradi- ance values for points close to the window

above the fire room and at a distance of three

feet from the exterior door. The irradiance level

at the exterior door was appreciably higher in

Test 1 due to flaming of the surface coatings on

the door and adjacent wall. The irradiance level into room 2-6 through the closed window in

Test 1 (as indicated by an outward-facing

radiometer) may have been high enough to cause ignition of drapes or other furnishings.

5.5 Smoke

Smoke accumulation in various rooms was

measured by the attenuation of light and ex- pressed in terms of percent of initial light

transmittance (T). Readings were converted to optical density per foot, (1/L) logio (100/T),

where L, the optical path length was twice

the smoke meter-to-ceiling height, approximately 14 feet. No corrections were made for

possible slight drift in the phototube circuits,

for the moisture or soot deposits on the lenses

and mirrors, or for the scattering of daylight

by the smoke. The results are plotted in figures

12, 13 and 14. These results represent the accumulated or

total smoke concentration in the various rooms

adjacent to the fire room as measured over a

vertical path, and are essentially independent

of smoke stratification eff'ects. In a typical fire situation, smoke stratification could alter the

time period prior to the onset of impaired visibility. Decreasing values following a maximum

may be due to smoke settling or agglomeration,

loss through openings, etc., but in the case of

Tests Nos. 2 and 3, were principally due to the

condensation of the moisture vapor portion of

the "smoke" aerosol.

11
0 20 40 SO

TIME, min

FiGtJRE 12. Smoke density, Test No. 1.

1 1 1

TIME, min FiGXJRE 13. Smoke density, Test No. 2.

160 TIME, min

FiGXJRE 14. Smoke density. Test No. 3.

12

5.6 Toxic Combustion Products

In Test No. 1, positive indications were obtained for CO and HCN, but not for COo nor

HCI. In Test No. 2, several measurements for

HCl also proved negative. In Test No. 3, observations were limited to CO, COo and HCN and were taken only in Rooms 2-3 and 2-4. The

maximum indicated gas concentrations and the

corresponding times for all tests are given in I table 4. Readings taken in the fire room (Room \ 2-3) in Test No. 3, although listed for informa-

| tion, are questionable because of: (a) excessive ' water vapor condensation in the sampling tube,

and (b) temperatures in excess of the recom- mended operating range. i

Table 4. Maximum gas concentrations indicated by Draeger

and MSA colorimetric tubes.

Test No. Room Time

Indicated concentrations

CO CO 2 HCN

1 1-5

1-8 2-6

min

25, 47

50

ppm

7,500

No pc 2,500

%

)sitive rea

ppm

30

dings

5 5254

2 1-1 1-4

2-3

72

27, 69

62, 70

58, 63 33

70 700

150

8 50

3 2-3

2-4

3

2110

5026

10,000

3,000

13

4

25

25

Because of the limited number of spot readings taken, the lack of positive readings should

not be taken as proof of the absence of the component. Also, no verification was made of the

manufacturer's claims for accuracy of the gas

indicator tubes. The use of the recorded values

as true concentration values may be limited by

a nuniber of factors, including the effects of

elevated temperature, the absorption of gas on

the surfaces of walls and on smoke particles,

interpretation of the color change and interfering reactions by other gases and water vapor.

5.7. Deflection

Test No. 1 Vertical and lateral deflection measurements

are shown in figure 15. Rapid deflection of the

floor at the center of the room above followed

shortly after the ceiling of the fire room
dropped and all structural members became di- rectly exposed to fire. The maximum deflection

observed was 7.4 in, with a permanent sag of

about 6 in after cooling. At the mid-span of the

joists, the maximum deflection observed was

21/4 in.

20 40 60 80

TIME, min

Figure 15. Deflections and extensions, Test No. 1.

The exterior light aggregate concrete panel

at the measurement location had deflected

(bowed out) 0.5 in at 41 min when the wire

fastening came loose. After the test, it was

noted that the panels had bowed out a maximum of about two inches.

Test No. 2 Vertical and lateral deflection measurements

are shown in figure 16. The maximum deflec- tion of the floor of the room above was 0.95 in at its center and 0.60 at the center of the span,

both reached at 65 min.

The outward movement of the concrete north

wall, at a point centrally located with respect to the fire room, reached a maximum of 0.06 in at 30 min, and then slowly receded. At 85 min,

when readings were discontinued, the net move- ment with respect to the original position was

0.06 in inward.

Expansion of the 20-ft second floor slab

(east-west), measured by means of an invar

wire, occurred gradually and reached a maximum of 0.44 in at 70 min. A complementary

measurement using dial gages on the east and

west exterior walls (total span 32 ft) gave an

overall extension of 0.49 in maximum at 89 min

with a drop-off to 0.34 in after nearly 5 hr. The

0.6

0

0.2

0.1

i.<

1

1

—

1 1

» ^ A

SLAB EXPANSION

^NORTH WALL EXTENSION

1—MIO- SPAN DEFLECTION

FLOOR DEFLECTION _

CENTER OF ROOM

1

1 DO-O

1 20 40 60 80 100 TIME, min Figure 16. Deflections and extensions, Test No. 2. maximum east-west expansion at the first floor

level was 0.08 in. Meaningful dial gage extension measure- ments on the exterior aluminum sandwich

panel were not possible due to frequent flexures

inward and outward, following burnout of the

polystyrene core. Visual observation of II/2 iri extensions were noted during test. Test No. 3 Maximum deflections of the roof slab were

1.3 and 1.2 in at the center of the room and at mid-span, respectively. These occurred at 40

min. After 2i/2hr, when readings were discontinued, the slab had recovered about 1/2 of

this deflection.

The aluminum sandwich panel bowed in 1/2 in

within 2 min, and then reversed, bowing out- ward gradually and continuously to a reading

of 2% in at 30 min.

6. Discussion

Because of time and monetary limitations,

field burnout tests are performed under a very

restricted number of possible conditions. Such

tests are neither standardized nor completely

controllable, and considerable variations in

time-temperature exposure may be encountered.

It is clear that the area of ventilation openings

(windows, cracks, etc.), the direction and magnitude of winds, and the type and orientation

of the combustible load are of vital importance.

6.1. Burnout Tests

A burnout test is one which involves complete burnout of the combustible contents of a

13
room or building'. Such tests may be performed

simply to measure the temperatures attained,

but are more commonly done to gauge, directly,

the possible life hazards which might result

from an actual fire involving actual or assumed

contents.

It is generally recognized that the customary

furnishings of most dwelling rooms provide

enough fuel to create a serious fire, and that

the critical survival point in accidental dwelling-room fires may be reached in less than 10

min [7,8]. The critical survival point may re- sult from toxic concentrations of combustion

gases, decreased levels of oxygen content, impaired visibility due to smoke, or elevated temperatures, and of these, the decrease in visi- bility (and associated irritating effects) due to smoke is generally reached earliest [7,8]. For

multi-story apartment buildings, it is also nec- essary to protect the building- against any local

structural failure which could endanger occupants.

The expression "fire severity" is commonly

used to denote the intensity (i.e. temperature

rise) and duration of a fire in terms of the

equivalent exposure time in the standard fire endurance test. Nearly 40 years ago, Ingberg

[9] reported the results of a series of burnout

tests in experimental fire-resistive structures at the National Bureau of Standards, and formulated an approximate relationship between the

combustible load (lb per sq ft of floor area)

and the "equivalent fire duration" (hr). To

make convenient the determination of "equivalent fire duration" from the burnout tests, the area under the standard furnace time-temperature curve plus cooling curve, and above an assumed baseline temperature, was measured

in degree-hours. This was done for a number of

fire exposure periods, and a curve was prepared in which these areas were plotted against

the standard fire durations. Then, by measuring the area under the time-temperature curve from a burnout test in the same units and

above the same baseline temperature, the equivalent fire duration of the latter could be read

directly.

The assumption that equal areas under temperature-time fire exposure curves stand for

equivalent severity of exposure, was realized at that time to be an approximation only, since

temperature and time do not both enter into the

heat conduction equation as linear factors. It must be further realized that the amount of

combustible load (or its total calorific value)

is not the only factor governing the resultant

temperature history within a room, but that the

type and distribution of the load, as well as the

number, size and arrangement of ventilation

openings, the thermal insulating qualities of the

enclosing structure, and the presence of "external" factors such as wind and humidity, are

usually of considerable importance. For example, the lower the thermal conductivity of the j interior surfaces, the higher the room air temperature. Calculations indicate that a decrease

in thermal conductivity by a factor of 10 could

result in a 300 to 400 deg F higher room tem- . perature [10].

The best available information on the combustible contents of representative types of

occupancies and buildings was obtained about ' 1940 [11, 12]. From a total of 13 apartments

and residences which comprised the survey, it 1 was found that the movable-property combus- | tible contents of an entire apartment or resi- \ dence averaged 3.4 lb/ft- (range 2.4 to 4.9 i lb/ft-) over all areas, including basement, bath- 1 room, bedroom, kitchen, living room, etc. The ( average value for bedrooms, closets included, ! was 5.0 \h/fV- (range 2.5 to 7.3 lb/ft=), and for

living rooms 3.9 Ib/ff- (range 1.4 to 6.8 Ib/ft^)

.

It was on the basis of these considerations that

Pratt Institute suggested and we concurred in , the selection of a fuel load corresponding to 6 lb/ft- floor area.

' The total heat released by the complete burnout of 6 lb/ft- of nominal 2- by 4-in lumber

arranged in lattice-type cribs is no greater than

that from the complete burnout of 6 lb/ft- of

wooden furniture arranged in a conventional manner. However, since the rate of fire growth

in a "typical" furniture fire could vary widely

depending upon its type, and upon the orientation of furniture with respect to sources of

ignition, the use of closely-stacked cribs and

simultaneous ignition was considered preferable and more readily reproduced. This ar- rangement produced a fire of considerable \ severity. For evaluating the fire safety of a

structure by a single test demonstration, such ; a burnout test is not considered unreasonable or

unrealistic. \ 6.2. Fire Intensity i For comparison purposes, the average fire | room air thermocouple temperatures are plotted ) in figure 17 for all three tests. The differences \ may be attributed to: (a) wind and ventilation I effects, including the vagaries associated with i fallout of window glass and the development of j. other wall openings, and (b) differences in thermal, physical and combustible properties \ of the room surfaces. i Comparing the two concrete wing tests, the .i cooling effect of the strong southerly wind in

Test 2 prevented simultaneous ignition of all i cribs and the pattern of fire development was i appreciably slower than that of Test 3. Although the wind in Test 3 was also southerly i and somewhat unfavorable to rapid fire devel- ii opment, complete flame involvement with sub- ; sequent fallout of the aluminum-faced polystyrene core sandwich panel occurred.

14
1400

1200

20 30 TIME.min

Figure 17. Comparison of fire room mean air temperature.

measured with fast-response thermocouples, 1 ft. below

ceiling _ASTM E-119 fire exposure, slow-response thermocouples

prescribed.

In Test 1, wind did not appear to affect fire development significantly. The flashover which

occurred at. 15 min is not unusual for rapidly

developing fires in rooms with suitable ventilation and a fire load of 6 lb/ft-. Flashover has

been noted in previous burnout tests, including some with mock furnishing of less than 4 Ib/ff-

[13]. However, the involvement of the asphaltimpregnated paper and glass-fiber composite

wall structure may have been a contributing

factor to the severity of the fire which developed. It is estimated in Section 6.7 that the

composite combustible floor, burnout of which

was extensive, could have provided nearly

15,000 Btu per sq ft or the equivalent of 1.9

lb/ft- of fire load.

The collapse of the gypsum board ceiling was

probably the result of the combination of the

contraction of the gypsum board due to calci- nation shortly after flashover, and the thermal

expansion of the steel supporting members. ' There is some evidence that concrete structures, especially when uninsulated and relatively moist (as for example, the ceiling and

party wall slabs in Rooms 1-3 and 2-3), may

have a moderating effect on the temperature

built up during fires. For example, the addi-

' Such rapid and complete dropout of the gypsum board ceilini; was not observed during- a recently-performed ASTM E-119 test on

a floor-ceiling assembly of similar construction.

tional heat required to vaporize and raise the

temperature of 1 lb of water to 1382 ^F is 1700

Btu. If 10 percent of the moisture content (assumed to be 10 percent by weight) in the two

directly exposed concrete members were vaporized and heated to fire temperature, this would

represent over 5 percent of the heat supplied by

the fire load. Although the temperatures in both

concrete wing tests were considerably below

those in the steel wing test, no definite conclusions on this point appear justified. The use of

heat flow transducers to measure the heat

absorption of walls would be desirable in future

tests.

6.3. Radiation

A principal means for fire spread from one burning building to another building across an

open space is by radiant heat transfer. Radiant

ignition can occur at distances considerably

greater than those to which flames generally

extend. Fire may also be spread by the flow

of hot gases (convection) or by flying brands,

but the heating of surfaces by radiation greatly

increases the likelihood of ignition from these

sources. The radiation hazard is reduced by

providing adequate separation between buildings, or by providing a barrier wall with suffi- cient fire resistance to prevent the passage of an appreciable amount of heat for the duration

of a fire. The two factors which govern fire spread by

radiation are (1) the radiation level which will

ignite materials both on exterior building sur- faces and on the interior building contents near window openings, and (2) the intensity of radiation from a building fire. Since the radiation

emitted depends upon the flaming area and the

fire temperature, it is clear that fire in a building with large windows (or other openings)

may be more hazardous than one in which the

percentage of openings to wall area is small. A

reliable evaluation of the fire exposure hazard

is important in urban area design, especially in

view of the trend towards larger windows, and

lightweight curtain walls of low fire resistance.

Techniques for determining permissible separation distances between buildings [14,15] are

usually based on an irradiance of 1.1 Btu/ftsec, since dry, bare wood may ignite at this

level in the presence of a small pilot flame, as for example, a spark or flying brand. Neglecting the effects of wind and of flames outside of

windows, a radiation intensity of 15 Btu/ftsec is stated to represent a conservative esti- mate of the emission from the openings of a burning building. However, as noted for Test

1, the peak radiation level was 1.4 times this

value due to flames extending outside the window. (In field burnout tests of typical singlefamily homes [7], peak radiation levels of 5

15
to 10 times this level were measured) . Also, for

the purposes of such calculations, it is important to consider as an opening any non-fireresistant wall, i.e., a wall that might collapse

and fall out during the course of a fire.

6,4. Smoke

Measurements were made for the purpose of

estimating the extent of smoke buildup which

could seriously obstruct human vision during a

building fire. From past experience with accidental fires, and in controlled burnout tests

[7, 8] , decrease in visibility is often considered

to represent a major life hazard to occupants.

A criterion sometimes used is based on the

assumption that, when the "visibility" (or

visual range) of a handlamp-illuminated sign

drops to 4 ft, a room is smoke-logged to a degree that would seriously impede the escape of

occupants [16]. It was inferred that this limit

was reached when the light transmitted over a

4-ft path was reduced to 0.25 percent of the

value in the absence of smoke, or an optical

density of 0.65 per ft. Williams-Leir [17] has

experimentally verified this threshhold level and determined that it corresponded to the

ability to distinguish a 10-W lamp in a smokefilled room at a distance of 11 ft, under idealized

conditions involving dark-adapted observers

stationed outside a smoke-filled room. On the

other hand, it has been reported that observers

within a smoke-filled room became "apprehensive about personal safety" when smoke con- centration reached levels corresponding to approximately 40 percent and 80 percent light

transmittance at a distance of 10 ft, depending

on whether or not self-contained breathing apparatus was used [18].

Laboratory studies of smoke measurement

[19] have indicated the desirability of making

measurements over a vertical rather than a

horizontal light path, since this provides a distinctive measure of the total smoke accumulation irrespective of vertical smoke stratification.

Total smoke accumulation values, expressed in units of optical density per foot, may be con- siderably different from smoke density values

measured horizontally at some particular level,

say 5 ft above the floor ("eye level"), especially during the initial smoke buildup. As the

smoke quantity increases, greater mixing and a

close approach to uniform smoke distribution

generally occurs. In this study, all results represent total smoke accumulation values, and not

smoke density at eye level. If it is assumed that a light transmittance of

16 percent over a viewing distance of 12 ft is critical, the limiting optical density would be

0.066 per foot. On the assumption of uniformly

distributed smoke within the room, comparative critical times are summarized in table 5. The similarity in time periods for the three

measurement locations may be noted. As ex- pected, smoke penetration to the adjacent room

(through openings around the closed connecting door) became critical in 2 to 7 min.

Table 5. Time to reach smoke density 0.066 -per foot

Location in relation Test Test No. 2 Test No. 3

to fire room No. 1

Adjacent room (same 4 min 7 min 2 min

apartment)

Adjacent apartment 21 min not reached 24 min

Room above - 47 min 47 min not appli- cable

It was determined, subsequent to completion

of the tests, that the smoke meters probably were not completely free from the effect of

smoke-scattered daylight entering through the

windows. (This is generally minimized by

proper collimation of the light beam source and

the use of appropriate apertures in the smoke

meter). Laboratory evaluation of the meters

following the test series revealed that the smoke

density test readings were lower than they

should be, approximately 10 percent low at the

limiting optical density. However, the effect

upon the times listed in table 5 is estimated to be relatively minor.

6.5. Toxic Combustion Products

The upper and lower limits of the measuringranges for the colorimetric indicator tubes used,

and some references to the toxic hazard limits

of these gases are summarized in table 6. The

toxic limits are not well defined, but may serve

as a guide in evaluating the indicated concentrations of toxic combustion products.

It can be seen from the values in table 4, that

the indicated concentrations of CO, HCN and

CO:,, in the room adjacent to the fire room,

approach or exceed those which can produce

breathing difficulties upon brief exposure. In. Test 1, where an appreciable separation between the floor and wall panel occurred, a criti- cal concentration of CO was measured in the

room above the fire room. No measurements in

the critical concentration ranges of these gases were obtained in the adjacent apartment of the

steel or concrete wing. In all cases, the indicated concentration values apply to the particular measuring location, rather than to an "average" room concentration.

16
Table 6. Measuring range of colorimetric indicator tubes and toxicological data for selected gases

Data

Indicator tube data: Measuring range, lower Measuring range, upper Recommended upper temperature limit (tube

and test gas)

Toxicological data:" M.A.C.b

Difficulty in breathing or irritation on brief exposure Immediate danger to life (2 to 5 min)

Gas

CO

0.3%

4.0%

50° C.

0.001%

0.1%

38° C.

100 ppm.

1000 ppm

1%

CO2

1%

20%

50° C.

5000 ppm

5%

12-15%

HCN

2 ppm

150 ppm

30° C.

/

10 ppm

50 ppm

200-300 ppm

HCl

2 ppm

30 ppm

40° C.

5 ppm

35 ppm

1000-2000 ppm

» Draeger Information Sheets (includes toxicological references).

^ Maximum average atmospheric concentration for 8-hr exposure without injury to health, as adopted by the American

Conference of Governmental Industrial Hygienists, 1963.

6.6 Structural Effects

! There was no evidence of rupture or other

I sudden structural failure of the floor and roof

' assemblies tested. Nevertheless, since excessive

I deflection of a structural member under the

combined effects of load and fire exposure may

be of critical importance, a careful evaluation

of deflection is necessary.

Deflection limits for fire-exposed assemblies

I in buildings have not as yet been established.

1 However, vertical deflection criteria in terms of

' general design features have been proposed

[20] though not formally standardized for de-

! fining load failure of beams, floors and roof

I

i constructions during fire tests. Based on a

ii! survey of laboratory fire endurance tests on

' representative constructions, the requirement

j was proposed that both a maximum deflection

I D>LV800i, and a maximum hourly deflection

; rate R>L'^/lbOd be exceeded as an indication of

load failure. In these formulas, L is the span

' between supports of the member or element

found to be critical under fire exposure, and d

j is the distance between upper and lower exI treme fibers of the particular structural comj ponent or assembly. For those tests in which

]i the construction was subjectively judged to

j have failed to sustain the applied load, the comj puted failure times according to these criteria were generally consistent and in good agreeji ment.

f Whereas, in a laboratory fire test, the entire

span length L is loaded and fire-exposed, in

1 these tests only one-half the span was exposed

I to fire. Although the effective span length under

non-symmetrical heating conditions has not

been defined, use of the shorter, fire-exposed

length appears to be a reasonable approximation. This is supported by the measured deflections, shown in figure 15, where the maximum

deflection of the floor occurred at the center of

the fire room and was always more than three

times the corresponding deflection at the midspan of the joists. Thus, using L = 10 ft and d

(the depth of the joist) =1 ft, load failure was

arbitrarily considered to have occurred in Test

No. 1 at 26 min. It should be noted, however,

that the structure continued to support the 40

lb/ft" design load without collapse throughout

the test. Bowing of the unprotected steel column adjacent to the flre window of about 1/2 iri- occurred

in Test 1 according to visual estimate. This

bowing may have resulted from thermal expansion of the 10-in. girder, and was recovered on

cooling. However, it should be noted that the

column was stressed to only a small fraction of

its design load. Temperatures in excess of 825

°F and extending over vertical distances of

approximately 4 ft on the outer flange, 5 ft on

the inner flange and 3 ft on the web were

recorded. Some areas were exposed to this temperature for 15 min. The maximum temperature recorded was 968 °F. In recent burnout

tests at the British Fire Research Station, it was found that external unprotected columns

and beams directly exposed to the flames,

reached excessively high temperatures (more

than 1022 °F) for fire loads of 6.2 and 12.4

lb/ft-, but this did not occur for fire loads of

1.44 and 3.1 lb/ft- [21].

Prior to test, concern was expressed regarding the possible spalling of concrete if fire- tested while moist. Such spalling did actually

occur, and in Test 2, was sufficient to expose a

considerable number of reinforcing bars (see

fig. 18). It is anticipated that, with adequate

conditioning resulting in a close approach to moisture equilibrium, the tendency of concrete

members to spall under fire exposure should

decrease.

17
Figure 18. Reinforcing bars exposed by explosive spoiling of concrete wall. Test No. 2.

6.7. Potential Heat

Laboratory measurements were made of the

potential heat of many of the actual components of the floors, walls and ceilings of the test building. For component materials which were

not available, estimates were made of their

weights and potential heats based on previous

measurements on similar materials. All values are summarized in table 1, which is arranged

according to the locations of the materials in

the steel or concrete wing.

Table 7. Potential heat of construction materials

Material Nominalthickness Density

Residue

after

firing

Potential heat

Weight

basis

Finish floor 114sqft

Steel Wing Room 1-6:

f Asphalt tile Particle board. Gypsum board*

Glass fiber Gypsum board*

Vinyl cove strip molding

1Gypsum board*

Steel joist* Gypsum plank*

Ib/cu ft 12445

15

Walls

(Composite wall*

I Steel curtain wall

\ Glass fiber insulation* _ . Gypsum board*

Light aggr. concrete panelConcrete Wing, Room 1-3: Finish floor, 123 sq ft, same as above..

Ceiling, hollow-core concrete slab Composite wall*.

Walls

Reinforced concrete* Polystyrene foam

Gypsum board* Aluminum sandwich panel*

Concrete Wing, Room 2-3: Gypsum board partition2

3 H

3

1^4

8

8

1

2y>

Ib/sqft 1.25 0.95

(2.0) 0.44

(2.0) 0.136 lb per ft 52 1 2.16

8.1 lb per ft (10.5)

219

36

%

63.3

0.1

(75.) 90.7

(75.) 16.2

(75.)

(90.) (80.)

Btu/lb

3410

8050

(650) 890

(650) 9050

(650) (1000)

(0)

3.40

(0.16; (2.0) 9.0

6.64

95.4

(80.)

(75.) 67.2

1210

(2000)

(650) 1120

92.9 -20

0.16

1.48

(1.66)

4.20

(95.) 0.0

(75.)

(61.)

71.7

17020

(760) (6660)

1000

*Not measured. Figures in parentheses were estimated on the basis of previous measurements on similar materials. 18
The potential heat test method was developed

several years ago [22] to measure the total

heat released under standardized conditions

representing a severe fire exposure, but without

regard to the rate at which the heat was re- leased. The method makes use of standard calorimetric techniques in which the burning of

small quantities of combustible material in an

otherwise inert material is assured by use of a combustion promoter which is added prior to

test. By measuring heat of combustion in an oxygen bomb calorimeter both before and after ex- posure to a "standardized fire" (2 hr in air at 1382 °F) , the difference may be considered as

the potential heat of the material. Determinations may be made on simple materials, or on

composite assemblies of materials from which

a representative sample can be taken.

The potential heat values in table 7 are listed on a unit weight and a unit area basis, calculated from the gross heats of combustion and

the percent residue. On an area basis, the potential heat values range from slightly negative for

the hollow-core concrete ceiling slab ( — 1200

Btu/ft-) , to nearly 15,000 Btu/ft^^ for the finish

floor assembly. The light aggregate concrete

panel in the steel wing had a potential heat of

10,100 Btu/ft". It was estimated that the

gypsum board/glass fiber composite wall and

the aluminum/polystyrene core sandwich panel

had potential heats of 9420 and 11,060 Btu/ft%

respectively. The steel curtain wall assembly

including gypsum board and glass fiber insulation was estimated to have a potential heat of

5730 Bt«/ft^

It is quite evident that the burnout of the 6

lb/ft- of combustible furnishings produces a

severe fire, but one which cannot possibly re- lease the total heat stored within the complete

thicknesses of the floor, walls and ceiling construction. As previously noted, the additional

heat which was released during the burnout

tests came primarily from the surface layers,

from layers exposed when the surface layers

fell off, or from combustible cores into which

heat could readily penetrate. For example, a measurement was made on the light aggregate

concrete panel removed from an area near the

window on the steel wing after the burnout

test. Its potential heat was measured as 550

Btu/lb, just one-half of its value prior to test. Other materials released smaller or larger fractions of their potential heat during the burnout

tests. As a rough estimate for the entire room, the

potential heats of the floor, walls and ceiling

have been computed on the basis of their re- spective areas and totalled in table 8. Of the

approximately 6.57 million Btu of total potential heat in Room 1-6 of the steel wing an es- timated 2.89 million Btu is considered to be

"readily available" for release during fire burnout. This includes the potential heats of the

gypsum board and steel joists of the ceiling, of

the gypsum board and glass fiber insulation of

the exterior steel wall, and of one-half of the

exterior concrete wall and of the interior composite walls. For the floor, the potential heats

of the asphalt tile and the particle board are

included. Similarly, only 2.34 million Btu is

Table 8. Estimated construction fuel load

Construction fuel load

Material Based on total potential heat Based on estimated

portion involved

Steel Wing, Room 1-6: Ceiling/floor Exterior concrete wall Exterior steel wall

Interior composite walls (2). Floor/ceiling

Vinyl cove strip molding

Btu/sq ft

17,730

10,100

5,730

9,420

17,730

TOTAL.

Concrete Wing, Room 1-3: Ceiling/floor Exterior concrete wall Exterior aluminum sandwich panelInterior composite wall

Interior concrete wall

Floor/ceiling

13,700

3,840

11,060

9,420

0 13,700

TOTAL.

Btu

2,022,000

606,000

344,000

1,535,000

2,022,000

45,000

6,574,000

1,685,000

230,000

686,000

670,000

0 1,685,000

4,956,000

Btu

322,000

303,000

97,000

768,000

1,358,000

45,000

2,893,000

-37,500

230,000

343,000

335,000

0 1,465,000

2,336,000

Ib/sq ft floor area ^

Equivalent combustible, taken as 8000 Btu per lb.

19
considered to be readily available of the approximately 4.96 million Btu of total potential

heat in Room 1-3 of the concrete wing. The

readily available portions of the potential heat

in the steel and concrete wing rooms may be

considered equivalent to 361 and 292 lb of combustible, respectively, taken as 8000 Btu per lb.

On a floor area basis, this would be equal to 3.2

lb/ft- for the steel wing room and 2.4 lb/ft- for

the slightly larger concrete wing. Of these

totals, nearly 12,000 Btu per sq. ft, equivalent to

1.5 lb/ft-, were contained in the composite

finish floor.

7. Summary

The importance of full-scale burnout tests in

providing valuable supplementary fire performance data was demonstrated in a series of three

burnout tests in an experimental test building.

Using a wood crib fuel load of 6 lb/ft- representing combustible contents, and a structural

design load of 40 lb/ft- applied to the floor or roof above the fire room, these burnout tests permitted study of the fire eff'ects on floor-wall

joints, smoke penetration through doors and

openings, and other complex interactions not

generally feasible in conventional laboratory

fire tests. With regard to the specific objectives established by Pratt Institute for fire protection, the

following results and comments were noted:

1. In both constructions, a small amount of

flaming penetrated to the room above the fire room primarily through the development of

separations between the floor assembly and the

curtain walls. Some fire and smoke also penetrated through wall openings provided for elec- trical outlets. Fire penetrated gradually to the

adjacent apartment in Test No. 1 through progressive smoldering of the composite party

wall. Direct heat transmission through either

the concrete floor or the joist and gypsum plank

floor was not excessive. In both constructions,

the party wall (between apartments) acted as an effective smoke barrier for about 20 to 25

min, based on an optical density (total smoke

accumulation) of 0.066 per foot. This critical

smoke level was not attained in the room above

the fire room until after 45 min in both cases. Within the measurement limitations specified,

critical toxic gas concentrations were either never reached, or in the case of carbon monoxide in the room above the fire room in Test

1, only recorded after the critical smoke level was reached.

2. There was no evidence of rupture, col- lapse, or other structural failure within the

boundary of a floor or roof assembly during

test. However, an appreciable vertical deflection

of the floor system in Test No. 1 was recorded.

In the absence of established deflection limits

for fire-exposed building assemblies, proposed

criteria based on laboratory fire endurance

tests on floors and roof assemblies were applied,

and, based on the assumptions used, "load

failure" was considered to have occurred in

Test No. 1. The test plan did not include design load

stressing of the unprotected exterior columns.

However, sustained temperatures in excess of

825°F and a peak temperature of 968°F were

recorded on the steel column adjacent to the

fire window in Test No. 1, and at these temperatures, steel members are known to undergo

appreciable loss in strength.

3. Laboratory measurements were made of

the potential heat of many of the actual components of the floors, walls and ceilings of the test building. Estimates were made of that portion

of the total potential heat stored within the

complete thickness of the floor, walls and ceil- ing construction which is readily available for

release during the burnout of the combustible

contents of a room. On this basis. Room 1-6 of

the steel wing contained a total "available"

fuel load equivalent to 3.2 lb/ft- of combustibles,

and Room 1-3 of the concrete wing contained

the equivalent of 2.4 lb/ft-. Of these totals,

nearly 1.5 lb/ft- was contained in the composite

finish floor. Slow fire propagation occurred in

Test No. 3 from the prolonged burning of the

foam polystyrene core of the aluminum-faced

sandwich panel.

The successful completion of the burnout test program was accomplished through the "team"

efforts of many members of the Fire Research

Section, and other individuals, whose assistance

is gratefully acknowledged: Les Furlow and

John Watkins of the Photographic Services Section, NBS; Dr. John Rockett and Larry Orlofl',

of the Factory Mutual Research Associate Program; Cliff Carlson, Mel Abrams, and Sam

Selvaggio, of the Portland Cement Association;

and Professors John H. Callender and Ed Shifter, Mr. Bob Davison and Miss Pat Wilson, of

the Research Department, Pratt Institute

School of Architecture.

20
8. References

[I] standard Methods of Fire Tests of Building Construction and Materials. American Society for Testing Materials, Designation E 119-(;i, 1961.

[2] Cost Reduction Methods for High-Rise Apartments; 2-Technical Standards. School of Architecture, Pratt Institute, June 30, 19G4.

[3] Standard Types of Building Construction, National Fire Protection Association, Designation

NFPA 220, 1961.

[4] Shiffer, E. T., "Progress in Building—A Research

Project Puts New Techniques to the Test of Use" The Architectural Forum, 123, No. 1, 80-83, July-Aug. 1965.

[5] McGuire, J. H., and Wraight, H., "Radiometer for Field Use" J. Sci. Inst. 37, 128-130, Apr. 1960.

[6] a. Scott Draeger Multi-Gas Detector, distributed by Scott Aviation Corporation, Lancaster, N. Y.

b. MSA Colorimetric Carbon Monoxide Tester, Mine Safety Appliances Co., Pittsburgh, Pa.

[7] Shorter, G. W., McGuire, J. H., Hutcheon, N. B., and Legget, R. F., "The St. Lawrence Burns,"

Quarterly of NFPA 53, 300-316, 1960.

[8] "Operation School Burning" and "Operation School Burning No. 2" Official Reports on A Series of School Fire Tests Conducted by the Los Angeles

Fire Department, published by the National

Fire Protection Association, 1959, 1961.

[9] Ingberg, S. H., "Tests of the Severity of Building

Fires" Quarterly of NFPA, 22, 43-61, 1928.

[10] Kawagoe, K., and Sekine, T., "Estimation of Fire

Temperature-Time Curve in Rooms," BRI Occasional Report No. 11, Building Research Insti- tute, Japan, 1963.

[II] "Fire-Resistance Classifications of Building Constructions" BMS 92, National Bureau of Standards, 1942.

[12] Ingberg, S. H., Dunham, J.W., and Thompson, J.

P., "Combustible Contents in Buildings," BMS

149, National Bureau of Standards, 1957. [13] Bruce, H. D., "Experimental Dwelling-Room

Fires," Report No. 1941, Forest Products Laboratory, 1959. [14] Law, M., "Heat Radiation from Fires and Build- ing Separation," Fire Research Technical Paper

No. 5, HMSO, London, 1963.

[15] McGuire, J. H., "Fire and the Spatial Separation

of Buildings," Fire Technology 1, 278-287, 1965. [16] Kingman, F. E. T., Coleman, E. H., and Rasbash,

D. J., "The Products of Combustion in Burning

Buildings" Brit. J. Appl. Chem. 3, 463-468, 1953. [17] Williams-Leir, G., private communication.

[18] Shern, J. H., "Smoke Contribution Factor in the Fire Hazard Classification of Building Materials," ASTM STP 422, 1967.

[19] Gross, D., Loftus, J. J., and Robertson, A. F., "A Method for Measuring Smoke from Burning

Materials," ASTM STP 422, 1967. [20] Ryan, J. V., and Robertson, A. F., "Proposed Criteria for Defining Load Failure of Beams,

Floors, and Roof Constructions During Fire

Tests," J. Research NBS, 63C, No. 2, 121-124,

Oct.-Dec. 1959. [21] Butcher, E. G., Chitty, T. B., and Ashton, L. A., "The Temperature Attained by Steel in Building

Fires," Fire Research Technical Paper No. 15, HMSO, London, 1966. [22] Loftus, J. J., Gross, D., and Robertson, A. F., "Potential Heat—A Method for Measuring the Heat Release of Materials in Building Fires,"

ASTM Proc. 61, 1336-48, 1961.

Time

1:30

2:30- 3 vinyl stripping. 5:00 One sq ft section of window glass fell out; smoke filling room 1-5 through

door separations. 9:00 Heavy white smoke. Room 1-5. 10:00 Window glass bowing out at top. 13:30 Floor tile burning. 14:45 Window glass fell out; first flames out

of window.

15:15 Flashover

15:45 Part of east partition wall fell into fire 16:00 Exterior door badly charred upper half; bowed in % in. 16:15 Paint ignites on outside of exterior door. 16:45 Flaming from exterior wall panel above

window.

17:00 Flames reach top of second floor window.

19:00 East partition wall burning; flames reach radiometer. 20:30 Clock stopped; paint burning on exterior column

20:45 Second floor window pane out. 22:00 Clock and stake on fire. (22:00-23:00 Gypsum board ceiling fell)

Part of west partition wall fell into fire; heavy smoke from second floor window.

Flames dying down.

More active flaming

Flames dying down; stucco on steel curtain wall panel flaming; panels de- forming.

33:00 No further flaming out of window.

34:00 Remainder of second floor window pane

fell out. 35:00 Interior of steel curtain wall bare of gypsum board and insulation. 39:00-53:00 Sections of east and west partitions fell.

Post -Test Observations

1. Steel Curtain Wall Panels— Buckling and distor- tion to roof level. Exterior stucco surface had ignited

and burned on a portion of panels. Poured gypsum fire- stop fairly effective except where pierced by electrical conduit. A few localized areas where fire propagated in the insulation of second-floor wall. No insulation or gypsum board remained on wall of fire room after fire test.

2. Light Aggregate concrete Panels— Severe outward

bowing. 1- to 2-in. separation from floor system pro- vided access for smoke and fire to upper floor. No access where panel butted up against exterior column. Polystyrene aggregate burned out. Very little structural strength remaining.

9. Appendix

Test No. 1 25:00

28:00

I Detailed Test Observations 29:00

30:00

Heavy smoke

:30 Cracking: of window srlass and fallout of

21
3. Interior Door—Passage of flame above door frame

into Room 1-5. Floor tile blistered.

4. Joists— Maximum permanent deflection approximately 6 in. on both joists along centerline of Room 1-6. Web rods near walls badly buckled. No apparent break

in welds between joist and girder.

5. Spandrel Beam (North)— Sag (less than 1 in.), distortion and warping.

6. Girder (East)—No excessive distortion. Fire stop

above girder generally effective except where inter- rupted for structural members and electrical conduit.

7. Exterior Co^wmw-Temporary distortion and bowing, estimated at % in. over length, recovered on cooling.

8. Gypsum Board-Glass Fiber Composite Wall—Yevy

little of the gypsum board panels on the fire-exposed

layer of the walls remained after fire test. Holes for

electrical conduit (BX conduit), radiant heaters and

thermostats permitted the passage of smoke into adjoining rooms on the first floor. No smoke penetration

through second floor partitions. Asphalt-impregnated

paper flamed and produced heavy black smoke.

9. Fioor—considerable burnout of asphalt tile floor. 10. Wiridow— Upper two-thirds of aluminum window

frame melted. Test No. 2

Detailed Test Observations

0:30 Dark smoke, becoming light at 2 minutes. 6:00 Window glass cracking; heptane flames from two pans only. 7:00 Section of upper right glass pane (¥2 ft" area) fell out. 8:10 Smoke at ceiling, Room 1-4. 9:00 Single crib only burning; upper edge of glass pane leaning out approximately

2 in. 14:00 Heavy white smoke in Room 1-4. 20:00-26:00 Bulging of aluminum sandwich panel, ap- proximately 1- to IV2 in. in some places.

26:00 Exterior door bowing about in. 29:30 Increase in smoke from fire room, upper

two-thirds of right windowpane fell out. 31 :30 Concrete spalled off back wall. 35:15 East wall of fire room bowed in. 41:00 Window blown out by explosive concrete

spalling; heavy black smoke; fire build- ing up. 44:00 Flashover; fiames out of window.

47 :00 Gypsum board layer on east wall of fire room down.

41:00-70 Intermittent violent spalling from south and west walls. 58:00 Joint crack on exterior (North) wall about in.; reinforcing bars in west

wall exposed.

60:00 Water dripping down wall, Room 1-1; separation at wall of Room 1-2, ap- proximately V4, to % in. 67:30 Insulation in east wall exposed through

large opening.

72:00 Smoke heavy in Rooms 1-4 and 2-3. 73:00 Handle and upper portion of exterior door charred badly.

75:00 Flames receding; water weeping down

exterior (north) wall. 86:00 Joint crack on exterior (north) wall ranges in width from "Iz2 in. (base) to

^/ifi in. (top of bldg.).

88:00 Smoke (steam) in Room 1-1 increasing

from ceiling down.

Post -Test Observations

Room (Fire Room) Severe spalling of concrete on north and especially west walls, with many rein- forcing bars exposed. Maximum spall depth, up to J

in. Aluminum sandwich nanels intact except for hole

in inner ply at upper corner of window; polystyrene

insulation burned out; aluminum straps distorted se- verely. No spalling of hollow-core concrete floor slabs forming ceiling, but gridwork pattern of cracks over

entire ceiling with severe cracks (Vie in.) at SW corner. Cracks at ceiling joints. Vie in. to % in. Gypsum board

cover for steel angle still in place for approximately 6

ft. East wall— outer ply of gypsum board % down, glass

fiber insulation exposed. Large crack (1% in.) between

this and aluminum sandwich panel. Door frame warped

door bowed out slightly; wall above and around door

badly blackened. Room i-.Z — East wall—floor to ceiling separation (Vs

in.) at concrete wall joint; separation from aluminum

door frame, % in.; stain damage due to extensive con- densation and runoff. No damage to south, north or west walls. Room- 1-2—'Ho damage.

Room i-4 — Cracks in hollow-core concrete floor slabs forming ceiling. Fire damage along upper 3 ft of inter- section of composite wall and aluminum sandwich panel

{IV2 in. separation). The composite wall caved in to- ward Room 1-3, maximum 5 in. Fire penetration damage between wall and door frame limited to upper 2 ft; door and frame reasonably undistorted. Scorch marks

on upper 8 in. of closet facing composite wall. No

apparent damage to basemold (along 4 walls) or vinyl

molding around closet. Extensive and general smoke

and water sweat marks.

Room ^-i — Floor to ceiling separation in East wall (party wall) joint, and corresponding roof slab joint.

Maximum separation about s/ie in. closing up to about

in. when cool. Additional hairline cracks at cornerjoints between prefabricated gypsum board partition wall and concrete wall and roof slabs. Steam penetration through hairline cracks. Room 2-2— Haii'line cracks at ceiling joints; separation 1/16 in. upper half of joint at poured concrete wall

filler unit. No damage due to fire, smoke or water (from

concrete sweating)

.

Room 2-5— North wall— separation of floor both hori- zontally and vertically approximately % in.; slight

evidence of smoke penetration under basemold; floor to ceiling crack in gypsum board. East wall (gypsum

board partition) intact. West wall—floor to ceiling cracks

(3/i6 in. max) at wall panel joint; hairline cracks and

water (concrete sweating) damage up to 2 ft above

floor. South wall (aluminum sandwich panel) —separation from floor approximately % in. vertically and hori- zontally; fire and smoke penetration between panel

and basemold at two locations above floor, SW corner

of room . Room 2-4 — Separation of partition from roof panels,

5/16 in. max provides clear access to Room 2-3. Maximum separation at floor ^li^ in. vertically in SW corner;

Vs in. horizontally NW corner. Separations of closet and

of gypsum board (east wall) from roof slabs. Cracks

along all hollow-core concrete roof slab joints. No fire, smoke or water vapor damage.

Exte7-ior— North side—major floor to roof cracks (

%

in. max after cooling) along vertical mortar joint east

of exterior door. Slight hairline cracks at other vertical joints further east. Foundation (concrete block) cracks

at NE and NW corners. Shear crack at floor level of poured concrete flller unit (near exterior door) with

in. horizontal displacement. South side— separation (

%

in.) of aluminum sandwich from concrete wall. Cracks

and separation of concrete balcony units, both floors. East and west sides—hairline cracks in vertical mortar

joints only.

Test No. 3

Detailed Test Observations

3:10 1% sq ft section of window glass fell out. 4:00 Another V2 sq ft section of window glass fell

22
out; strong flaming observed in west and

center cribs. 7:00 Left aluminum sandwicli panel warped at upper right corner. 9:50 Window frame and aluminum sandwich panel

bowed out at top approximately 1 in. 10:30 Entire center portion of left aluminum sand- wich panel bowed out. 19:10 Flames bathing entire rear wall. 20:30 Smoking drops of boiling plastic expelled

from top of window frame.

24:00 Cracks developing in east (gypsum board

partition) wall; flame? reach window.

28:10 Remainder of window glass fell out. 28:30 Thick flames fill upper half of room.

30:15 Aluminum window frame melting and falling

out. 31-32 Concrete spalling.

32:50 Aluminum sandwich panel fell out; entire

side open; complete flame involvement.

33:20 Heavy spalling.

44:30 Collapse of last crib; occasional flames and

smoke from aluminum sandwich panel of east room.

47:00 Flaming in partition near door to east room.

50:00 Very few flames visible in fire room.

58:00 Smoke issuing from bathroom vent to roof. 59:00 Asphalt dripping from floor ledge. 60 to 150 Slow smoldering and occasional flaming with

smoke and charring progressing in alumi- num sandwich panel of east room.

Post-Test Observations

Room 2-3— (Fire room) Concrete spalling on north and west wall, but no reinforcing steel exposed; maximum depth IV2 in. Gypsum board cover over steel angle

still in place although sagging in spots. Slight asphalt

dripping from roof through ceiling slab joint. Gypsum

board partition wall erect, but practically unsupported.

Opening along vertical joint of concrete wall; several other small cracks and separations. Separation between

interior door frame and north concrete wall. Room 2-^—Blisters on interior door except for lower

4 in. Scorch marks (from ceiling to mid-height) on wall adjacent to door. Several holes through aluminum sand- wich panel; polystyrene core burned out except for sec- tions above and on east side of window frame. Maximum separation of aluminum sandwich panel approximately IM in. at southwest corner of room. Separations

at hollow-core concrete roof panel joints not appreciably

greater than from Test No. 2.

•{t U.S. GOVERNMENT PRINTING OFHCE: ml 0—

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