in

Reference

NBS

Publications A 1 1 1 ( MD7bfl2

J NBSIR 82-2488

Fire Endurance Tests of Selected

Residential Floor Construction

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

April 1982

Sponsored in part by:

U.S. Department of Housing and —QC Urban Development

2QQ Washington, DC 20410

. U56

82-2438

1982

NBSIR 82-2488

FIRE ENDURANCE TESTS OF SELECTED

RESIDENTIAL FLOOR CONSTRUCTIONS

IUT10N41. MilttU

OF ITAKDA.1W3

t. IMF AWT

JUl 7 1982

/To-t c~.cc-- /

JL£

J. B. Fang

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory ( Center for Fire Research

Washington, DC 20234

April 1982

Sponsored in part by:

U.S. Department of Housing and

Urban Development

Washington, DC 20410

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler. Director

TABLE OF CONTENTS

Page

LIST OF TABLES iv

LIST OF FIGURES v

Abstract 1

1. INTRODUCTION 2

2. EXPERIMENTAL DETAILS 3

2.1 Test Furnace 3

2.2 Test Assemblies 4

2.3 Structural Loading 7

3. TEST MEASUREMENTS 8

3.1 Temperature 8

3.2 Floor Deflection 10

3.3 Furnace Pressure 10

3.4 Heat Flux and Flow Rate 10

3.5 Gas Concentrations and Data Acquisition 11

4. TEST PROCEDURE 11

4.1 Fire Test 11

4.2 Fire Endurance Criteria 12

5. TEST RESULTS 13

6. DISCUSSION 17

7. SUMMARY 25

8. RECOMMENDATIONS 27

9. ACKNOWLEDGEMENTS 28

10. REFERENCES 29

APPENDIX A - CALCULATION OF THE LOAD TO BE APPLIED DURING THE

FIRE TEST 30

APPENDIX B - LOG OF GENERAL OBSERVATIONS DURING TEST 1 34

APPENDIX C - DERIVATION OF THE EQUATIONS USED FOR CALCULATING

RATE OF HEAT PRODUCED IN TEST FURNACE 36

iii
LIST OF TABLES

Page

Table 1. Descriptions of test assemblies, applied load, and

fire exposure conditions 42

Table 2. Initial weights and total available heat of

combustible materials in test assemblies 43

Table 3. Summary of the fire endurance times of floor/ceiling

assemblies under furnace fire conditions 44

Table 4. A comparison of failure times of floor assemblies

evaluated in the test room and in the fire endurance

furnace 45

Table 5. Flow rates of air and fuel supply, oxygen content in

flue gas, incident heat flux, and char rate 46

Table 6. A summary of heat release during fire endurance

testing 47
LIST OF FIGURES

Page

Figure 1. Construction details and instrumentation layouts for

test assembly no. 1 48

Figure 2. Construction details and instrumentation layouts for

test assembly no. 3 49

Figure 3. Construction details and instrumentation layouts for

test assembly no. 10 50

Figure 4. Layout of steel blocks distributed uniformly over

the top of the test assembly 51

Figure 5. Floor plan of test furnace showing locations of

thermocouples and pressure probes 52

Figure 6a. Average Furnace Gas Temperature Measured with fast

response thermocouples 53

Figure 6b. Average furnace gas temperature measured with fast

response thermocouples 54

Figure 6c. Average furnace gas temperature measured with fast

response thermocouples 55

Figure 7a. Average furnace gas temperature measured with ASTM

thermocouples 56

Figure 7b. Average furnace gas temperature measured with ASTM

thermocouples 57

Figure 7c. Average furnace gas temperature measured with ASTM

thermocouples 58

Figure 8a. Air flow rate to the furnace for tests 1-7 59

Figure 8b. Air flow rate to the furnace for tests 8-10 60

Figure 9a. Fuel flow rate to the furnace for tests 1, 3-5 ... 61

Figure 9b. Fuel flow rate to the furnace for tests 2 , 6 , 1 ... 62

Figure 9c. Fuel flow rate to the furnace for tests 8-10 .... 63

Figure 10a. Oxygen concentration in flue gas stream 64

Figure 10b. Oxygen concentration in flue gas stream 65

Figure 10c. Oxygen concentration in flue gas stream 66

v
LIST OF FIGURES (continued)

Page

Figure 11a. Average upper furnace static pressure for

tests 3-5 67

Figure lib. Average upper furnace static pressure for

tests 6 and 7 68

Figure 11c. Average upper furnace static pressure for

tests 8-10 69

Figure 12a. Total rate of heat release in furnace for tests 1,

3-5 70

Figure 12b. Total rate of heat release in furnace for tests 2,

6, 7 71

Figure 12c. Total rate of heat release in furnace for

tests 8-10 72

Figure 13a. Comparison of rates of heat release in furnace for

tests 1 and 2 73

Figure 13b. Comparison of rates of heat release in furnace for

test 8 74

Figure 14a. Average total heat flux for tests 1 and 2 75

Figure 14b. Average total heat flux for tests 3-5 76

Figure 14c. Average total heat flux for tests 6 and 7 77

Figure 14d. Average total heat flux for tests 8-10 78

Figure 15a. Comparison of calculated and measured heat flux

incident at south wall for test 1 79

Figure 15b. Comparison of calculated and measured heat flux

incident at east wall for test 1 80

Figure 15c. Comparison of calculated and measured heat flux

incident at sourth wall for test 2 81

Figure 15d. Comparison of calculated and measured heat flux

incident at east wall for test 2 .......... 82

Figure 15e. Comparison of calculated and measured heat flux

incident at south wall for test 8 83

vi
LIST OF FIGURES (continued)

Page

Figure 16a. Exhaust gas concentrations for test 1 84

Figure 16b. Exhaust gas concentrations for test 2 85

Figure 16c. Exhaust gas concentrations for test 3 86

Figure 16d. Exhaust gas concentrations for test 4 87

Figure 16e. Exhaust gas concentrations for test 5 88

Figure 16f. Exhaust gas concentrations for test 6 89

Figure 16g. Exhaust gas concentrations for test 7 90

Figure 16h. Exhaust gas concentrations for test 8 91

Figure 16i. Exhaust gas concentrations for test 9 92

Figure 16j . Exhaust gas concentrations for test 10 93

Figure 17a. Total heat release and heat release by fuel for

test 1 94

Figure 17b. Total heat release and heat release by fuel for

test 2 95

Figure 17c. Total heat release and heat release by fuel for

test 3 96

Figure 17d. Total heat release and heat release by fuel for

test 4 97

Figure 17e. Total heat release and heat release by fuel for

test 5 98

Figure 17f. Total heat release and heat release by fuel for

test 6 99

Figure 17g. Total heat release and heat release by fuel for

test 7 100

Figure 17h. Total heat release and heat release by fuel for

test 8 101

Figure 17i. Total heat release and heat release by fuel for

test 9 102

vii
LIST OF FIGURES (continued)

Page

Figure 17 j . Total heat release and heat release by fuel for

test 10 103

Figure 18. Proposed fire exposure curve 104

Figure 19. Comparison of thermocouple types at center of

furnace for test 8 105

viii
Fire Endurance Tests of Selected Residential Floor Constructions

J . B . Fang

National Bureau of Standards

Washington, D.C. 20234

A series of ten load-bearing, wood- and steel-framed

residential floors was evaluated for structural fire resistance in a fire endurance furnace. Nine wood-frame and one

light guage steel-frame, protected and unprotected floorceiling assemblies, each measuring 3.05 x 2.44 m in size,

were exposed from the underside to either the newly

developed high- intensity , short-duration fire exposure or the standard ASTM E119 temperature-time curve. The fire

endurance time based on the passage of flames to the

unexposed face of the floor with unprotected wood joists

varied from 6 to 9 minutes under the newly developed fire

exposure and 16 to 18 minutes when subjected to the standard

ASTM fire exposure. Under the identical fire exposure, the

exposed steel-framed floor failed in approximately 4.5

minutes compared to 9 minutes for the unprotected wood-frame

floor. The wood floors evaluated in the test furnace had a shorter fire resistance period in comparison with those

tested previously under room fire conditions, probably due

to faster charring rates and additional heat contribution

from the burning of combustible materials in the structure

with the excess air present in the furnace. The heat

contributed by the burning floor assemblies was measured by

the oxygen consumption technique.

Key words: fire endurance, fire tests, flame through,

floors, furnace tests, joists, steel, wood.

1
1 . INTRODUCTION

In order to minimize the spread of fire beyond the room of origin,

building codes may specify fire endurance requirements for floors,

walls, and ceilings so that they act as barriers to withstand fire

exposure without loss of design function. This provides time to permit

building occupants to evacuate safely and fire fighters to bring the

fire under control prior to collapse of the building. However, there are no fire endurance requirements in the codes for single family

residences. The standard ASTM E119 test method [1] developed more

than a half century ago, is commonly used for evaluating the fire

endurance of building components for use in public buildings, institutions, apartment buildings, etc., which require ratings of one hour or more. This test would have several shortcomings if it were used to

establish ratings of less than one hour for residential floor assemblies

if they should be required by the codes for single family residences in

the future. The unrealistically slow buildup of the furnace temperature and the customary use of negative pressures and high levels of excess air which are not present in a room fire, as well as the slow

time response of the furnace thermocouples used for temperature control,

make the E119 test unsuitable for the above purpose. This report

describes the last stage of a research project to establish a new fire

endurance test for residential floor assemblies. The gas temperature

versus time curve, the gas pressure below the ceiling, and the oxygen

concentration required were established by a series of basement recreation room fire tests using modern furnishings [2,3]. A series of selected

floor/ceiling assemblies were then tested in this room under the above

set of conditions [4]. In the last phase of the project, reported here,

some of the assemblies were tested in a furnace modified to produce the

above conditions of temperature, pressure, and excess air. The fire

endurance times of these selected assemblies were compared between the

room fire, the furnace test with the new exposure, and the furnace test

with the E119 exposure. The heat contributed by the burning floor

assemblies was measured by the oxygen consumption technique.

2
2 . EXPERIMENTAL DETAILS

2.1 Test Furnace

The entire series of fire endurance tests were conducted with a pilot furnace having internal dimensions of 2.95 m long x 2.44 m wide

and a height of 2.85 m. The furnace can be used for testing 2.44 x 3.05-m (8 x 10-ft) floor assemblies in a horizontal position, or 3.05 x 2.44-m (10 x 8-ft) high wall panels in a vertical orientation.

The basic construction of the furnace consists of a fire brick floor

0.18 m in total depth and 0.34-m thick composite walls, each consisting

of a 6.4-mm thick steel plate shell, 76 mm of block insulation, 203 mm

of castable refractory brick, and 51 mm thick ceramic fiber block

lining.

The furnace is fired with natural gas. Originally eight

nozzle-mixing gas burners were distributed evenly into 2 rows of 4

burners each over the floor area, and mounted on the bottom of the

furnace in an upright position. Each burner supplied combustion air

through a center tube and fuel gas through a grid over an annular space

around the tube. This construction is designated Furnace Modification I. The heat output rates from a single burner ranged between 70 and 350 kW.

The heat output rate from each burner was controlled by regulating the

fuel flow rate while the air supply was maintained at a constant rate.

Due to the presence of unstable flames, these upward firing burners

were replaced by two new gas burners which were installed horizontally

from the west furnace wall and used for tests 6 and 7. This construction is designated Furnace Modification la. These new medium-velocity,

nozzle-mixing gas burners fed gaseous fuel through the center tube of

the concentric nozzle and supplied air through the annular space around

the tube. Each burner had a wide operating range, from 18 to 440 kW.

Also, these burners used a stoichiometric fuel air mixture and were

capable of operating without flame instability under a reducing

atmosphere. For tests 8 to 10, an additional six new gas burners were

3
put in the east and west furnace walls. This construction is designated

Furnace Modification lb

.

The fire endurance test furnace was situated within a large, air

conditioned building to minimize the effect of variable outdoor weather

conditions. It was fitted with one observation window in each of three

sidewalls of the furnace. Combustion products were vented through four

dampered flues, one in each corner of the furnace, that were connected

to a common exterior stack. A variable speed blower was used in the

stack for the last five tests to provide better control of the pressure.

2.2. Test Assemblies

Each floor-ceiling assembly measuring 2.44 m wide by 3.05 m long

(8 x 10 ft) was laid atop the specimen support frame installed around

the edges of the top opening of the furnace. This produced an exposure

area of 2.18 x 2.79 m (7.17 x 9.17 ft). The assembly was subjected to an approximately uniform distributed load, applied by means of steel

blocks

.

The following types of floor assemblies were tested and a descriptive summary of the main structural elements, applied loading,

and fire exposure conditions for individual tests are presented in

table 1.

Assemblies 1, 2, and 8

The floor framing consisted of nominal 51 x 203-mm (2 x 8-in) wood

joists spaced 0.61 m (24 in) on center, with the exception of two end

joists positioned 0.59 m (23 1/4 in) from the adjacent joists to

accommodate the 2.44-m (8-ft) furnace width. The construction details

and instrumentation layout of the floor assembly are shown in figure 1.

Each joist was kiln-dried, construction grade no. 2, southern pine.

Each joist was 2.97 m long and both ends were secured to nominal

4
51 x 203-mm wood rim joists with two 90 mm (3 1/2 in) long 16d common

nails. The rim joists were toenailed using 16d common nails spaced

0.41 m on center to wood sill plates resting on top of a layer of 64 mm

(2 1/2 in) thick fire brick that covered the specimen support frame.

The sill plates were pressure treated southern pine lumber. Crosssection dimensions were 38 x 127 mm (1 1/2 x 5 in) for assembly 1, and

38 x 114 mm (1 1/2 x 4 1/2 in) for assembly 2. The latter size placed

the edges of sill plates flush with those of the specimen support frame.

Solid wood bridging was installed along the mid-span of the floor joists

A single layer of 18-mm (23/32-in) thick underlayment grade,

Douglas fir plywood subfloor was laid with the long dimension perpendicular to the joists and the end joints staggered 1.22 m (48 in)

between the adjacent rows. The plywood was supplied in 1.22 x 2.44-m

(4 x 8-ft) sheets with tongue and groove edges on the long sides and

marked APA Group 1, interior with exterior glue. The subfloor was

secured to each joist with 64-mm (2 1/2- in) long 8d coated common nails

spaced 0.15 m (6 in) on center along edges and 0.25 m (10 in) on center

along intermediate members. The pockets formed by the plywood subfloor,

the rim joists, and the sill plates were filled with 89-mm (3 1/2 in)

thick, Rll glass fiber insulation blankets with aluminum foil faced

vapor barrier. An olefin carpet with foam rubber backing was fastened

to the plywood deck at its perimeter with 16-mm (5/8- in) long carpet

tacks placed 0.2 m (8 in) apart.

The ceiling was a layer of 16-mm (5/8- in) thick, type X, gypsum

wallboard positioned with long edges at right angles to the floor joists

Wood pieces, which were cut from nominal 51 x 102-mm southern pine

lumber, were installed along the outer boundary of fire exposed surface

of the assembly. The gypsum board was secured to the joists and

boundary with 45-mm (1 3/4-in) long coated drywall nails spaced at

0.15 m (6 in) on center along the edges of the board and 0.3 m (12 in) on center in the field. All exposed nail heads and joints were taped

and covered with joint compound, and the ceiling-wall seams were

5
finished with wood trim. The exposed face of the gypsum board ceiling was painted with two coats of white interior flat latex paint.

Assemblies 3 to 7 and 9

Each test assembly was similar to assembly 1, except there was no gypsum board ceiling. The floor system was supported by nominal

51 x 203-mm (2 x 8-in) kiln dried, construction grade no. 2, southern

pine joists spaced 0.61 m (24 in) on center, with the exception of a 0.59-m (23 1/4-in) spacing for the two end joists aside from their

adjacent ones. Figure 2 shows the construction details of the unprotected floor-ceiling assembly and the arrangement of instrumentation.

The sill plates, each measuring 38 x 114 mm (1 1/2 x 4 1/2 in) in

cross-section, were made from the sections of nominal 51 x 152-mm

(2 x 6-in) pressure-treated southern pine lumber. The subfloor was

18 mm (23/32 in) thick, underlayment grade, Douglas fir plywood with

tongue and groove edges on the long sides. An olefin carpet with foam

rubber backing was installed on top of the plywood deck.

Assembly 10

The structural members used to support the floor-ceiling assembly

were C-shaped galvanized steel joists, 184 mm (7 1/4 in) deep with a 45-mm (1 3/4- in) flange, a 14-mm (9/16-in) stiffening lip, and a 1.26-mm (18 gauge) thickness. The joists were spaced 0.81 m (32 in) on center beginning with one joist placed along the horizontal centerline

of the furnace width and each joist was strengthened at both ends

through short web reinforcement, i.e., attachment of a short piece of

the steel joist, 152 mm (6 in) in length, to the web of the floor joist.

Figure 3 shows the details of the test floor and the layout of

instrumentation. Each joist was cut 2.97 m (117 in) long and fastened

to nominal 51 x 203-mm (2 x 8-in) wood rim joists with two 64-mm

(2 1/2-in) long, 8d common nails driven through steel end clips. The

rim joists were toenailed to 38 x 114-mm (1 1/2 x 4 1/2-in) wood sill

6
plates resting on the top of a single layer of fire bricks over the

support frame for the test specimen, with 90-mm (3 1/2-in) long 16d

common nails spaced 0.41 m on center.

The subfloor was 18-mm (23/32-in) thick, underlayment grade,

Douglas fir plywood with tongue and groove edges on the long sides and

marked APA group 1, interior with exterior glue. The plywood was laid

with the long dimension perpendicular to the joists and secured to the

steel framing using 48-mm (1 7/8- in) long type 512 screws spaced 0.15 m

on center at the panel edges and 0.30 m on center at the intermediate

supports. The 2.44 m by 3.05 m olefin carpet with a foam rubber backing

was fastened to the plywood deck with 16-mm (5/8-in) long carpet tacks

spaced approximately 0.2 m on center along its perimeter.

Prior to the fire test, the moisture content of wood-base materials

used in the assemblies was determined with an electric moisture meter

by measuring the electric resistance between two pin-type electrodes

driven into the wood. The moisture content was found to range from 7 to 9 percent with an average of 7.9 percent for wood joists, and from

7 to 8.5 percent with a mean value of 7.3 percent for the plywood

subfloor. The initial weights and the estimated total available heat

of combustible materials for each test assembly are listed in Table 2.

The calorific values used for the potential heat calculations were

18.6 MJ/kg (8000 Btu/lb) for the wood and 46.5 MJ/kg (19900 Btu/lb) for

the olefin carpet with foam rubber backing.

2.3 Structural Loading

Prior to fire exposure the test assembly was subjected to an approximately uniform load, which was achieved by evenly distributing

steel blocks over the top face of the assembly. Each steel block

measured 140 x 203 x 152 mm (51/2x8x6 in) and weighed 22.7 kg

(50 lbs). For tests 1 and 2 the applied load was calculated to stress

the floor joists to the maximum total deflection and the bending moment

7
permitted by design specifications. In order to compare the fire

performance results of the floor assemblies evaluated in the test

furnace with those obtained under the room burnout conditions [4] , the

structural loadings for tests 3 to 5 and 8 to 10 were selected to

develop the same magnitude of bending stresses in the floor joists as those produced in assemblies 3, 7 and 4 in the previous test series.

2 A live load of 265 kg/m (54 psf ) , which corresponded to approximately

93 percent of the respective maximum design load based on the maximum

allowable bending stresses for wood joists, was applied to each assembly

used in tests 3 through 9 as shown in Table 1. Detailed calculation of

the required load for assembly 3 is given in Appendix A and the layout

of steel blocks over the carpeted floor of the test assembly is shown

in Figure 4.

The temperatures of the combustion gases in the upper part of the

furnace chamber were monitored through nine commercial metallicsheathed, mineral-insulated, fast response thermocouples and nine ASTM

E119-standard protected furnace thermocouples. The average temperature

derived from either these fast response, or from the ASTM furnace

thermocouples was used to control the fuel input to the test furnace so that the newly developed temperature-time curve [3] or the ASTM E119

temperature-time curve, respectively, was followed. The equation used

to describe the newly developed temperature- time curve is the following:

3. TEST MEASUREMENTS

3.1 Temperature

o 1 2

( 1 )

o 1 2

where A = 0

o A = 3.83 x 10

1

B - 1 o

B = 4.49 x 10

8
A

2 = -1.58 X 10

A

3 = 9.05 x

10"

-2

B -4.56 x 10

-5

2 -8

B

3

3.36 x 10

and where T is in °C and t in seconds. The measuring junctions of the

thermocouples were located 0.31 m (12 in) below the supporting frame

for the test specimen or 0.38 m (15 in) below the bottoms of the floor

joists at the midpoint and quarter points of the lengthwise span as shown in Figure 5. All fast response thermocouples were commercially

made from 1.02 mm (0.04 in), diameter chromel-alumel wires, enclosed

within 6.4 mm (0.25 in) outside diameter stainless steel tubes having

a 0.9-mm (0.036- in) wall thickness and insulated with magnesium oxide.

The ASTM furnace thermocouples were of 1.02-mm (0.04-in) chromel and

alumel wires, insulated with porcelain tubes, and protected by capped

nominal 13 mm (0.5 in) diameter black wrought-iron pipes. The furnace

gas temperatures were also measured with five bare-j unction 0.51-mm

(0.02-in) diameter (no. 24B&S gauge), double-cable chromel-alumel

thermocouples. These thermocouples were positioned along the vertical

centerline of the furnace chamber at 0.31, 0,61, 1.42, 3.11 and 2.79 m

below the supporting frame for the test structure. The junctions were

formed by welding the chromel wire from one cable to the alumel wire

from the other cable in order to eliminate the current leakage through

the insulation materials within the individual thermocouple cables at

temperatures above 800°C. The surface temperatures of the furnace

walls at selected locations were measured with the thermocouple beads

attached to the exposed and unexposed surfaces of ceramic fiber blocks

installed as the hot face veneer linings over the existing refractory

linings. This low thermal inertia block lining was necessary to achieve

the very rapid temperature rise in the furnace required by the proposed

high intensity short duration fire exposure.

The temperatures of the unexposed surface of the test assembly

were determined with 15 bare-beaded, 0.51-mm (20 mil) wire diameter,

chromel-alumel thermocouples placed underneath ceramic fiber pads,

152 mm (6 in) square by 13 mm (0.5 m) thick, and attached to the top

9
surface of the carpeted flooring as shown in Figures 1 to 3 . The

temperatures of the top and bottom surfaces of the floor joists and the

unexposed surface temperatures of the plywood subfloor were also

measured with the bare-beaded, double-cable thermocouples.

3.2 Floor Deflection

The deflection of the test assembly during the test was measured

at the mid points and selected quarter points of three centrally

located floor joists as shown in Figures 1 to 3 . Nickel steel cables

and linear-displacement potentiometers mounted on a panel along with

small pulleys were employed to provide indications of the relative

movements of the floor surface.

3.3 Furnace Pressure

The static pressures at various heights inside the test furnace

were monitored continuously through four nominal 64-mm (1/4-in) diameter

steel pipes extending through the east and west walls into the furnace

with their open ends flush with the wall surfaces. The four locations

used for pressure measurements included one each at the east and west

walls along the vertical centerline of the interior wall 0 . 10 m (4 in)

down from the supporting frame for the test specimen, one at the west

wall 1.19 m (47 in) below the supporting frame, and the remaining one near the bottom of the east wall 2.72 m (107 in) away from the supporting

frame as shown in Figure 5. The exterior ends of the pipes were

connected by copper tubing to variable reluctance pressure transducers.

3.4

Heat Flux and Flow Rate

The total heat fluxes incident at selected locations were measured

with three Gardon-foil type, water-cooled heat flux gauges. Two of

these gauges were mounted flush with the internal surface of the south

wall 0.76 m (30 in) away from its vertical centerline and 1.19 m (47 in)

10
below the supporting frame for the test assembly, and one in the east

wall 0.31 m (12 in) away from its vertical centerline and 1.19 m (47 in)

down from the supporting frame.

The axial velocity of the primary combustion air inside a 0.25 m

(10 in) outside diameter, light-gage metal pipe was monitored continuously with a pitot tube in conjunction with a variable reluctance

differential transducer. The pitot tube was placed at the center of

the circular pipe facing upstream. The delivery rate of gaseous fuel

to the furnace burners was metered throughout the test with an orifice

plate flowmeter.

3.5 Gas Concentrations and Data Acquisition

Continuous gas samples were withdrawn from the flue gas stream

with steel tubing and analyzed for O

2

, CO

2

, and CO after passing through

a series of cold traps and filtering tubes. The concentrations of CO

2 and CO were measured with non-dispersive infrared gas analyzers and O

2 with a polarographic-type oxygen cell.

The output signals from the thermocouples and various transducers

were automatically recorded by a high speed digital data acquisition

system. The test data were logged every 8 seconds and then transferred

to the computer for processing, tabulating, and plotting.

4. TEST PROCEDURE

4.1 Fire Test

Each test assembly was built and installed in the test frame of

the furnace. A few days prior to fire exposure, the assembly was loaded

uniformly with steel blocks to the prescribed load density. The fire

test was initiated by igniting the aerated fuel gas from the burners

with spark-ignited gas bypass pilots. The readings from nine protected

11
fast response or ASTM furnace thermocouples were averaged to provide

the mean furnace gas temperature, which was made to follow the proposed

or the standard ASTM E119 time-temperature curve by manual control of

the gas flow to the burners. Visual observations and photographic and

video tape records were made of the burning characteristics of the test

assembly including floor deflection, time for burn-through , and time

for structural failure.

4.2 Fire Endurance Criteria

The fire endurance of a floor construction is characterized by the

time of failure defined as one of the following:

1. Structural failure is considered to have occurred when the test

assembly cannot withstand the applied load and collapses. The

collapse of the test assembly can be anticipated to occur when

2 the total deflection has equaled or exceeded L /800d, and the

2 rate of deflection has attained or surpassed L /150d per hour,

where L is the span between supports of a structural element,

in meters, and d is the distance between the upper and lower

extreme fibers of a structural component or assembly, in meters

[7]. For the assemblies tested, the critical values for the

deflection and the rate of deflection were equal to 48mm and

0.071mm/s, respectively.

2. Integrity failure is considered to have occurred when flames or hot gases have passed through the test assembly to its unexposed

side

.

3. Thermal insulation failure is considered to have occurred when

the average temperature on the unexposed surface of the test

assembly increased more than 139°C (250°F) above its initial

temperature or by more than 181°C (325°F) at any one point.

12
5. TEST RESULTS

A log of visual observations and records from video tape

recordings taken from above the test assembly during a typical test run

(test 1) is given in Appendix B. The following are general observations

of the performance of each test floor subjected to the prescribed fire

conditions

.

Assembly 1

Failure of gypsum board ceiling with falling of small fragments

away from the assembly was observed at 16 min: 25 sec. Penetration of

flames through the plywood deck/olefin carpet floor to the unexposed

side occurred at 20 min: 6 sec. The burn-through region was located

0.71m from the east furnace wall between the center joist and its

adjacent joist to the north. The deflection of the test structure

measured at the center point showed an appreciable increase after

18 min: 16 sec and attained a downward movement rate of 0.56mm/s at time

of test termination. The maximum values of the average and an individual temperature attained on the unexposed surface during the test

were 56 and 106°C, respectively, since the thermocouple locations were

away from the burn-through region.

Assembly 2

The protective layer of gypsum board used as the ceiling finish

began to disintegrate and fall from the test assembly at 30 min:20 sec. Failure of the floor assembly was observed at 34 min:0 sec by the

passage of flames through to the carpeted surface in a region 0.9m west

and 0.8m south of the center of the test floor. The floor was found to

sag more rapidly at 35 min: 4 sec with a maximum deflection rate of

0.35mm/s, which eventually led to the collapse of the center joist.

The average temperature of the surface thermocouples located away from

the burn-through region on the unexposed side, increased quickly to

13
241°C at 35 min: 8 sec and an individual temperature rise exceeded 181°C

at the same time.

Assembly 3

Flame penetration of plywood subfloor/carpet flooring was observed

at 6 min: 4 sec in the region centered at 1.07m west and 0.25m north of

the middle of the assembly. Floor deflection showed a significant

increase at 5 min: 10 sec, at which time the center joist was deforming

at a rate of Q.6mm/s. A total distance of 57mm occurred at 7 min after

the start of the test. The entire test structure collapsed and fell

into the furnace 2 min: 8 sec later than the structural failure time

calculated based on the deflection limits proposed by Ryan and

Robertson [7]. An individual temperature rise on the unexposed surface

near the center of the test floor exceeded 181°C at 6 min:34 sec, but

the average temperature was less than 49°C at time of test termination.

Assembly 4

Passage of flames and hot gases through the assembly to the

unexposed side occurred at 6 min: 7 sec. The burn-through region was situated between the west quarterpoint of the center joist and that of

its adjacent joist to the south and on the west side of the tongue and

groove joint between two sheets of plywood underlayment . Additional

penetrations of flames to the unexposed surface were observed at

6 min: 40 sec at several locations near the center of the test floor.

Structural collapse of the center joist based on floor deflection

measurements occurred at 7 min: 52 sec. One thermocouple positioned on the carpet in the vicinity of the center of the assembly indicated a steep temperature rise to 247°C at 6 min: 56 sec and the average surface

temperature rise of the unexposed face exceeded 139°C at 7 min:13 sec.

14
Assembly 5

The flame penetration of the carpeted plywood subfloor occurred at

7 min: 0 sec in the region centered at the east one-third point along

the joist located north of the center joist. The record of floor

deflection measured at the center of the test floor showed a considerable deflection rate at 8 min: 48 sec and the maximum downward flexure

rate of 3.4mm/s occurred at 10 min: 32 sec. One surface thermocouple

located on the carpet surface in the neighborhood of the burn-through

region registered 223°C at 10 min: 8 sec and the maximum average

temperature of the unexposed surface was 177°C at the end of the test.

Assembly 6

Penetration of flames to the unexposed surface was observed at

16 min: 8 sec in the middle of the area surrounded by the east furnace

wall, the center joist, the east tongue and groove joint between the

two sheets of plywood subfloor, and the floor joist south of the center

joist. The floor deflection measured at the center of the test assembly

increased rapidly at 14 min: 50 sec and the total deflection was 175mm

when the test was terminated at 16 min: 50 sec. A single thermocouple

on the carpeted floor near the center of the assembly indicated 209°C

at 16 min and the average value of the readings of surface thermocouples

on the unexposed side at test termination was 202°C above its initial

value.

Assembly 7

Flames penetrated the carpeted plywood deck near the east one-third

point along the floor joist located north of the center joist at

17 min: 35 sec. The region where the fire broke out was centered at

1.22m from the east furnace wall and 0.76m away from the north wall.

The downward deflection of the test floor increased steadily at a rate

of 2.7mm/s to a total distance of 303mm at 17 min: 40 sec. An individual

15
temperature, measured at the point 430mm northeast of the center of the

test floor on the unexposed face, showed a rapid increase to 217°C at

17 min: 10 sec and the average surface temperature increased to 106°C

after 18 minutes of test duration.

Assembly 8

The gypsum board ceiling near the center of the test structure

started to break up and fall at 15 min:40 sec. Penetration of flames

to the unexposed surface took place at 24 min: 22 sec in the space

between the center joist and its adjacent joist to the south near the

west tongue and groove joint of two sheets of plywood underlayment

.

The center of the f lame-through region was situated 0.91m from the south

edge and 0.69m from the west edge of the test assembly. A significant

increase in the floor deflection was noticed at 24 min:10 sec, and the

floor deflected downward at a rate of 6.3mm/s to a total distance of

150mm at 26 min: 30 sec. An individual temperature rise on the unexposed

surface located near the center of test floor exceeded 181°C at

25 min: 23 sec, but the average surface temperature was less than 102°C

throughout the duration of the test.

Assembly 9

Failure of the test assembly due to flames passing through to the

unexposed surface in the area located between the center and the south

joists and near the west tongue and groove joint formed by two sheets

of plywood subfloor was observed at 9 min: 09 sec. The burn-through

region was centered at 0.66m from the west edge and 0.94m from the south

edge of the test floor. The floor deflection measured at the center of

the test assembly attained a significant rate at 8 min: 30 sec and a peak

deflection rate of 0.88mm/s occurred at 10 min:00 sec. The temperature

rise of one thermocouple positioned on the carpeted surface near the

center of the test floor surpassed 181°C at 9 min:38 sec but the average

temperature of the unexposed surface was 74°C at time of test termination.

16
Assembly 10

The fire burned through the region situated above the intersection

of the centrally located floor joist and the west tongue and groove

joint between two sheets of plywood underlayment at 4 min: 38 sec. Deflection measurements at the center point of the test assembly indicated a rapid increase at 2 min: 45 sec and the maximum downward flexure

at a rate of 5.5mm/s occurred at 5 min: 47 sec. One individual thermocouple in contact with the carpeted surface near the center of the test

structure exceeded 181°C above its initial temperature at 4 min: 24 sec and the averaged temperature rise of the unexposed surface surpassed

131°C at 5 min:48 sec.

6. DISCUSSION

The newly developed temperature-time curve in Figure 6(a) was derived by approximating the upper layer gas-temperature history

obtained by fast response thermocouples from a typical test run in a series of basement recreation room burnout tests [3] with a smooth curve

and setting zero time as the beginning of the rapid temperature rise

period. The development of this new temperature- time curve, which

represents a high intensity, short duration fire exposure and is

regarded as a more realistic description of the severity of room fires

likely found in residential occupancies, was discussed elsewhere [3,4].

The gas temperatures plotted in the Figures 6(b) to 6(d) and 7 were

derived by averaging the readings of nine equally spaced thermocouples

located on a plane 0.38m below the underside of the test assembly.

Figures 6(b) and 6(d) illustrate the ability of the furnace to follow

the newly developed temperature time curve. Figure 6(c) illustrates

the departure of the furnace temperature from the newly developed

temperature-time curve when it is constrained to follow the E119 curve. The temperature in Figure 6(c) is measured with fast response

thermocouples, even though the furnace is controlled with the ASTM

thermocouples. The newly developed fire exposure has a steeper

17
temperature rise during the initial stage and a shorter period of time

at higher temperatures than the standard ASTM E119 curve. Figure 7 shows that temperatures as measured with the ASTM thermocouples for the

tests covered in Figure 6(d) follow the E119 fairly well from 5 minutes

onward. (The E119 curve is not defined between 0 and 5 minutes.)

Tests 1 and 2, which were of protected wood joist floors with a high

level of excess air in the furnace, showed rapid increases in their

peak levels toward the end of test period. This was due to increased

rates of heat released by combustion of the volatile products from the

pyrolyzing wood in the test structure with the excess air.

The performance of the floor-ceiling assemblies subjected to

various fire environments in the test furnace are summarized in terms

of fire endurance (periods) in Table 3. The fire endurance of a test

assembly is expressed as the duration of a specified fire exposure prior

to failure as defined by any one of the following events: (1) passage

of flames through openings or cracks developed in the assembly,

(2) structural collapse, and (3) attainment of an average temperature

of 139°C or an individual temperature of 181°C above the initial

temperature on the unexposed surface, whichever takes place earliest.

The structural failure time shown in the table was based on the instant

when the floor deformation exceeded both the total deflection of 48mm

and the deflection rate of 0.071mm/s in accordance with the load

failure criteria proposed by Ryan and Robertson [7]. For most of the

assemblies tested, the rate of deflection surpassed its specified limit

earlier than the total deflection. Also, listed in the table are the

maximum values of total deflection measured at the center of the

individual floor-ceiling assemblies.

As shown in Table 3, the failure times of the unprotected wood

joist floors due to flame-through varied from approximately 6 to

9 minutes for the newly developed temperature time curve (tests 3, 4,

5, and 9) depending on the amount of excess air available to burn the

exposed wood-base materials in the furnace and to deteriorate the

18
structural integrity of the floor. For conditions of the test refer

back to Table 1. A protective layer of 16mm thick, type X gypsum board

as the ceiling finish provided an additional fire endurance of

approximately 15 minutes for exposure to the new time- temperature curve

(test 1) and 18 minutes to the ASTM E119 standard fire exposure (test 2) . Under a similar rate of air supply to the furnace, the ASTM E119 fire

exposure appears to be less severe and results in a delayed failure

time for the floor assembly compared to the newly developed fire

exposure (test 2 versus test 1 and test 6 versus test 9) . The structural failure times listed in Table 3, as calculated from the failure

criteria developed by Ryan and Robertson [7], were shorter than the

times to actual collapse of the floor joists, which were observed

generally to occur soon after the termination of the test. These

deflection limits may be a useful alternate criterion for defining the

failure of load-carrying capacity of the building members. However,

the structural deflection may be affected by many factors which need to

be understood in order to establish the validity of the relationship

between the limits and actual test results. The times for the average

temperature of the nine uniformly-distributed thermocouples on the

unexposed floor surface to reach 139°C and for a single thermocouple

to reach 181°C above the initial temperature usually occurred somewhat

after the flames passed through the test structure. Also shown in

Table 3, the maximum deflection at the center of each test assembly

varied widely from about 50 to 330mm depending upon the degree of

charring and burning of floor joists, the type of fire exposure

employed, and the time from the f lame-through to test termination.

Table 4 presents the flame penetration times of the assemblies

evaluated in the fire endurance furnace compared with the failure times on the same constructions under room fire environments along with the

measured oxygen content in the flue gas stream. The protected and

unprotected wood-frame floors under the newly developed fire exposure

with small amounts of excess air exhibited passage of flames in

approximately 24 and 9 minutes, respectively, compared to 35 and 12

19
minutes under the fire conditions produced from the burning of typical

furniture and interior finish materials in a room [4]. The earlier

failure of the floors in the furnace was attributed to rapid reduction

in the thickness of the subfloor and in the cross-sectional area of the

floor joists caused by the more intense burning and faster charring

rates of the wood-base materials caused by the greater amount of excess air present in the test furnace. The passage of flames to the unexposed

side of the assembly in the furnace tests was purely burn-through of

the plywood subfloor, while in the room fire tests, the increased

deflection of floor joists with elevated temperatures promoted joint

separation and developed openings for flames passing through. The

flame-through time of the exposed light gauge steel-framed floor

assembly was comparable with that for the counterpart room fire test as both tests were run in fire environments with reduced oxygen levels.

Also illustrated in the table, the wood floors with and without the

gypsum board ceiling exposed to the ASTM E119 standard fire exposure

(tests 2 and 6) were penetrated by flames in 34 and 17 minutes,

respectively. In the first case, the excess air in the furnace was high and, in the second case, it was low.

Summary data on the average flow rates of the air and fuel gas

supply to the furnace, the concentration of oxygen in the flue gas,

average heat flux measured at furnace walls, and the average char rate

for the tests performed are tabulated in Table 5. The table also lists

the flow rate of excess air, which was equal to the difference between

the flow rates of air supplied and stoichiometric air required for

complete combustion of fuel gas. The average char rate for each

individual assembly was calculated from on the thickness of the plywood

subfloor and the total duration of fire exposure up to time of burnthrough. The char rate of the plywood deck was lowest for tests 6 and

7 which had the lowest amount of excess air. The char rates were

highest in tests 1 and 2. This may have been because the average

furnace temperature was higher during the exposure period which did not

start until the fire penetrated the gypsum board ceiling.

20
Figures 8 and 9 show the time variation of the volumetric flow

rates of air and fuel supplied to the test furnace for all of the tests.

The concentrations of CO^, CO, and 0

^ in the flue gas prior to

discharge to the chimney, are shown in Figures 10(a) to 10(j) as a function of time for the individual tests. As expected for a given air

supply rate, the oxygen level in the furnace gases decreased with

increasing inflow rates of the gaseous fuel and the volatile components

from the thermally decomposing cellulosic materials in the test assembly.

The gaseous fuel and combustible volatiles eventually burned to deplete

the available oxygen inside the furnace chamber. Figures 11(a) and

11(b) display the average static pressure in the upper part of the

furnace chamber as a function of time. These furnace pressures were

obtained by averaging the readings of two pressure probes, one each

positioned in the east and west furnace walls and 0.17 m beneath the

test assembly. Except for brief excursions, a furnace pressure of

15+5 Pa ( 0 . 06 + 0*02 in water column) was maintained throughout each

test after 2 min or less from the start except for test 5. In that test

the pressure within the furnace became less than atmospheric when it was necessary to reduce the rate of fuel and combustion air starting

about 4 minutes before the termination of the test. These negative

pressures caused cool air to be drawn into the furnace through various

cracks and openings developed in the test structure, increasing the

concentration of oxygen in the flue gas as illustrated in Figure 10(e)

.

This inward movement of cold air may have induced a greater heat loss

by convection from the exposed surfaces and resulted in a small increase

in the time to failure of test assembly 5 over that of 3 and 4 as shown

in Table 3.

The total rates of heat release in the fire endurance furnace as a function of time for the individual tests are shown in Figures 12(a) to

12(c) . The heat release rates were calculated from the experimental

data on the concentrations of 0- , C0 9

, and CO, and the flow rate of flue

gas using a heating value of 19210 kJ/m of oxygen consumed for the fuel

21
gas and the pyrolysis products from the assembly. The detailed

derivations of the equations utilized for the energy production calculations are given in Appendix C. The heat release rates for tests 1 to

7, which were run prior to installation of a pitot tube for flue gas

velocity measurement, were computed by assuming the mass flow rate of

the flue gas equal to the sum of the flow rates of the air and fuel gas

supplied to the furnace. In order to lower the furnace gas temperature

in test 8, to follow the descending portion of the newly developed

temperature-time curve, cooling water supplied at a rate of 139 g/s,

which corresponds to a heat extraction of 3/4 kW for water vaporization,

was injected into the furnace from 20 min after the start of the test

until its termination. No correction due to mass addition of cooling

water was made on the latter portion of the heat release rate curve for

test 8. As shown in the figures, the rates of heat production in the

furnace tests during the high-intensity, short-duration fire exposure

were significantly greater than those under the ASTM standard fire

exposure. For a given air supply rate, the unprotected floor assemblies

had higher heat release rates than the protected floors due to earlier

occurrence of ignition and heat production from the wood joists and the

plywood subfloor.

The heat release rates calculated by the oxygen consumption method

are compared to those derived from the fuel gas input rate multiplied

by its heating value for tests 1, 2, and 8 in Figures 13(a) and 13(b).

As shown, the rates of heat release computed from the measured flue gas

flow rates and oxygen concentrations were found to be in reasonably

good agreement (within approximately 3 percent) with the heat output

rates derived from fuel combustion. This approximation holds for the

period between ignition of the gas burners and disintegration of the

gypsum board ceiling. The continuous increase in the total heat release

rate toward the end of this period is attributed to the heat production

from the burning of the combustible materials of the test assembly in

the presence of excess air inside the furnace. The total amount of

heat produced in the test furnace and the heat output from the gas

22
burners due to fuel combustion for the time interval between the start

of the test and the occurrence of f laine-through at the floor for each

test are given in Table 6. Total heat production and fuel-contributed

heat production were obtained from integrations of respective heat

release rate vs. time curves mentioned previously. The low values in

total heat release for tests 6 and 7, as shown in the table, are questionable. There were some difficulties in the flue gas sampling

system at the beginning of the test for test 6 and in the air inflow

measurement for test 7. Table 6 also presents the amount of heat given

off by the individual assemblies, calculated from the difference between

the total heat production and the fuel contributed heat release. The

temporal variation of the total heat release and the amount of heat

produced by fuel combustion for each test are shown in Figures 14(a) to

14(j). Note that the total heat release rate curve on each figure

should be multiplied by a factor to make it coincide with the gaseous

fuel prior to the time at which the assemblies begin to contribute fuel.

This is necessary because of the inaccuracies in measuring the volume

flow rate in the furnace exhaust duct. At any given time, the

difference between these two curves provides a measure of the heat

released by the combustible assembly up to that time.

Figure 15 is a graph of the gas temperature for test 8 as measured

by three types of thermocouples positioned 0.38 m below the test

structure at the center of the furnace. The temperature readings of

the sheathed fast-response thermocouples fell between the readings of

the regular 0.5 mm double-cable thermocouples and the ASTM thermocouples

in response to the rapid increase in furnace gas temperature during the

early stages of the test. As the test progressed, the temperature

differences gradually decreased with decreasing rate of gas temperature

change

.

The change of the average incident heat flux with time measured at

the furnace walls for the various tests are shown in Figures 16(a)

through 16(d) . These heat fluxes for tests 1 to 7 were obtained by

23
averaging the readings of three total-heat-flux gauges installed with

the sensing elements flush with the interior surfaces of the south and

east furnace walls. For tests 8 to 10, the average value was derived

from two heat flux gauges situated in the south wall. The levels of

heat flux incident at the furnace walls during the high- intensity

short-duration fire exposure were generally higher than those observed

under the ASTM E119 standard fire exposure because of the fact that the

former exposure had higher furnace gas and wall surface temperatures.

In order to estimate the rate of heat loss to the furnace walls

and assess the accuracy and reliability of the direct measurements with

the heat flux gauges, calculations were made of the heat flux incident

at selected locations during the fire endurance test. These heat fluxes

at the exposed surfaces were computed using the measured surface

temperature data and the assumption that the furnace walls are thermally

semi- inf inite solids. The equations and procedures used for the heat

flux calculations are described fully in a previous report [3], For

these calculations the density, surface emissivity, thermal diffusivity,

and thermal conductivity of the ceramic fiber blocks utilized as

3 interior wall linings were, respectively: 133 kg/m , 0.95, 1.43 x

5 2 5 10 m /s, and 5.61 x 10 kW/m-K for the surface temperatures below 260°C,

and 3.01 x 10^T - 2.21 x 10^ kW/m-K, for the surface temperatures (T ) s s above 260°C. Figures 17(a) to 17(e) illustrate a comparison of the

calculated and measured surface heat fluxes, acting near the centers of

the south and east furnace walls, as a function of time for tests 1, 2,

and 8. As shown, there is reasonably good agreement between the

calculated heat fluxes and those determined with the heat flux gauges.

However, the measured heat fluxes should be greater than the calculated

values due to the higher rate of convective heat exchange with a water

cooled heat flux gauge. The difference between these curves may be

partially attributed to the uncertainty of the numerical values used

for the material thermal properties in the calculations. The rate of

heat loss to the furnace walls averaged over the period from the start

of the test to the failure of the gypsum board ceiling was estimated

24
from the surface temperature data and found to be approximately 195kW

or 10.6 percent of the rate of heat produced from fuel combustion for

test 1, HOkW or 8 percent for test 2, and 270kW or 14.9 percent of

total energy released in the furnace for test 8.

7 . SUMMARY

This is the final report of a long-term project to develop a fire

endurance test for residential floor construction. The ASTM E119 test

is not applicable here, where ratings of less than one hour are required, because (1) its slow rate of temperature rise is not characteristic of the burning of the combustible contents in modern dwellings,

(2) the slow response time thermocouples do not provide adequate control

during the critical, short duration of the test, and (3) the test is

conducted under negative or neutral furnace pressure which is not

representative of room fires. This project started with a residential

fire load survey [8] which led to the adoption of a standard

recreation-room configuration as the basis for a new test. The movable

2 2

contents fire load of 23 kg/m (4.7 lbs/ft ) included a polyurethane

couch and chair as well as other items of furnishing. A parametric

study of the effect of ventilation, interior finish, fire load, and

room size on the temperature-time curve developed during room fire

tests of this configuration was then conducted [3], Next a series of

room fire tests were conducted on seven selected residential floor

constructions using this basic configuration [4]

.

In the last phase of

this project, which is reported here, three of these assemblies were

tested in a fire endurance furnace using both the ASTM E119 and the

newly constructed temperature-time curve so that a comparison could be

made between the two types of exposure in the furnace and between the

furnace and the room fire test. Tests were also run with low and high

percentages of excess air in order to examine the effect of oxygen

concentration in the furnace on the failure time of combustible con- struction. The extensive research conducted on this project has

culminated in the recommendation of a new fire endurance test for

25
residential floor constructions. The following observations were made

as a result of the present tests:

1. The wood joist floors exposed to the newly developed fire

conditions in the gas-fired furnace had a shorter time to failure

compared with the earlier residential room fire tests on the same floor constructions. This was due primarily to the increased

burning rates of the combustible materials in the test structure

with the excess air present inside the test furnace.

2. Individual test assemblies resisted flame penetration in the

furnace fire tests for a time approximately 40 percent shorter

when tested under the newly developed time- temperature curve as compared with the ASTM fire exposure.

3. A protective layer of 16mm thick, type X gypsum board on the

ceiling acted as a thermal barrier on the fire-exposed side of

the assembly and increased the time-to-f ailure by approximately

15 minutes for the high-intensity, short-duration fire exposure

and by about 18 minutes for the standard ASTM E119 fire exposure.

4. The rates of heat release calculated by the oxygen consumption

method were generally consistent with the heat output rates of

the gas burners, up to the time of fuel contribution by the

assemblies. The difference between the heat release rate

calculated by the oxygen consumption method and the heat

output of the burner at later times provides a good measure

of the heat released by the assemblies.

5. In the case of the protected assemblies (tests 1 and 2) a steep

rise in the furnace gas temperature was observed immediately

after the combustible floor was involved in the fire. This was

the result of the rapid heat production from the combustion of

the flammable volatiles from the pyrolyzing wood-base materials

26
in the excess air atmosphere. This effect was reduced (test 8)

when the percentage of air supplied to the furnace was reduced.

It is important that the oxygen concentration in the furnace

exhaust duct be specified during the tests.

6. Under the new fire exposure condition, the unprotected wood-frame

floor suffered the passage of flames in 9 minutes compared with

4.5 minutes for the exposed light gauge steel-framed floor.

There was an opening up of seams due to the sag of the steel

joists in the latter case.

7. The fast response thermocouple has a shorter time lag and provides

a better indication of the true furnace gas temperature compared

with the ASTM E119 furnace thermocouple, especially during the

early stage of the test.

8.

RECOMMENDATIONS

The following recommendations are made:

1. A new fire endurance test should be submitted to ASTM for the

purpose of rating residential floor constructions which require

endurance times of less than one hour. The new test should

have the following features:

(a) The temperature-time curve shown in figure 6a and given by

equation 1 should be used to control the furnace temperature.

It is based on a series of residential recreation room fire

tests reported in NBSIR 80-2120. The proposed temperaturetime curve is shifted by 85 seconds from the one developed

in that report so that zero time corresponds to the

beginning of the rapid temperature rise period and coincides

with the time at which the gas is turned on in the fire

endurance furnace. It may be necessary to insulate the

27
walls of the furnace with ceramic fiber in order to achieve

the rapid rise portion of the prescribed temperature-time

curve

.

(b) The furnace temperature should be measured and controlled

by metallic-sheathed mineral insulated fast response

thermocouples described in this report.

(c) The pressure measured at the top of the furnace should be at

least +10 Pascals.

(d) The oxygen concentration of the flue gas should be as low as possible to correspond to the ventilation limited condition

in the room. Very low levels may be difficult to achieve in some furnaces. A level of 5 percent may be a practical limit

based on these experiments. The actual value measured during

the test should be reported.

2. The oxygen concentration in the exhaust flue during standard ASTM

E119 tests should be reported because of its impact on the failure

time of combustible constructions.

3. Oxygen consumption measuring equipment may be added to existing

ASTM E119 furnaces in order to obtain the heat release rate of

assemblies, whenever that information is requested.

9 . ACKNOWLEDGEMENTS

The author would like to thank Messrs. Oscar Owens and Thomas Maher

for constructing the test assemblies, Mr. Newton Breese for reducing

and processing the test data and preparing the graphs, and Messrs. Sam

Steel, Charles Veirtz, William Bailey, Billy Lee, Melvin Womble,

Richard Triplett and Michael Gibb for assistance in performing the fire

tests. Special thanks should go to Mr. William Parker for his advice

28
in the planning of the tests and for his valuable assistance in the

preparation of this report.

This project was supported in part by the U.S. Department of

Housing and Urban Development, under the program management of

Mr. James C. McCollom within the Division of Energy, Building Technology

and Standards, Office of Policy Development and Research.

9. REFERENCES

[1] "Standard Methods of Fire Tests of Building Construction and

Materials," ANSI/ASTM E119, 1981 Annual Book of ASTM Standards,

Part 18, pp. 879-904 (American Society for Testing and Materials,

Philadelphia, Pa., 1981).

[2] Fang, J. B., Static Pressures Produced by Room Fires, Nat. Bur.

Stand. (U.S.), NBSIR 80-1984 (February 1980).

[ 3 ] Fang, J. B. and Breese, J. N., Fire Development in Residential

Basement Rooms, Nat. Bur. Stand. (U.S.), NBSIR 80-2120

(October 1980)

.

[4] Fang, J. B., Fire Performance of Selected Residential Floor

Constructions Under Room Burnout Conditions, Nat. Bur. Stand.

(U.S.), NBSIR 80-2134 (December 1980).

[5] "National Design Specification for Stress-Grade Lumber and Its

Fastenings," National Forest Products Association, 1973.

[6] "Design Values for Wood Construction," A Supplement to the 1977

Edition of National Design Specification for Wood Construction,

National Forest Products Association (June 1978)

.

[7] Ryan, J. V. and Robertson, A, F., Proposed Criteria for Defining

Load Failure of Beams, Floors and Roof Constructions During Fire

Tests, J. of Res., Nat. Bur. Stand. (U.S.) 63C , 121-124 (1959).

[8]

Issen, L. A., Single-Family Residential Fire and Live Loads

Summary, Nat. Bur. Stand. (U.S.), NBSIR 80-2155 (December 1980).

29
Appendix A

Calculation of the Load to be Applied During the Fire Test

The design value for the nominal 51 x 203-mm (2 x 8- in) construction

grade no. 2, southern pine joists used in test 3 is given in

references 5 and 6 as follows:

allowable extreme fiber stress in bending, F^ = 8.27 x 10 Pa (1200 psi)

10 6 modulus of elasticity, E = 1.1 x 10 Pa (1.6 x 10 psi)

-5 4 4

moment of inertia, I = 1.983 x 10 m (47.64 in )

section modulus, S = 2.153 x 10 ^ m^ (13.14 in"^)

All floor joists were simply supported with a span length of 2.79 m

(110 in) and spaced 0.61 m (24 in) on center.

Dead load for Assembly 3:

Plywood subfloor (18 mm thick)

Wood joists and bridging

Carpet flooring

Total dead load

10.9 kg/m^

9.8 kg/m^

1.8 kg/m^

22.5 kg/m^(4.6 psf)

(1) Deflection

The maximum deflection allowable for a floor joist is limited to

1/360 of the span length and is equal to

D = = 0.00775 m (0.305 in) 360 360

The uniform load corresponding to this maximum total deflection at

mid-span can be calculated as

30
w

384 EID _ (384) (1.1 x 10

10

)(1.983 x 10

5 )(0. 00775)

5 4 4 L (5) (2.79)

= 2143 (N/m) = 218.5 kg/m (147 lb/ft)

and the maximum load distributed evenly on the floor joists with a 0.61m joist spacing is

total allowable load = 218.5 x — = 358 kg/m2 (73.4 psf)

The applied load permitted to meet the maximum allowable deflection is

live load = total load - dead load

= 358 - 23 = 335 kg/m2 (68.6 psf)

(2) Bending Moment

The maximum bending moment occurs at the center of the span and can be

calculated as

M = F S = (8.27 x 10

6

) (2.153 x 10

4

) = 1781 N-m (15770 in-lb)

b

The total load per unit length on a joist, which induces this maximum

bending moment is

w

(8) (1781)

(2 . 79)

2 = 1830 (N/m) = 186.6 kg/m (125 lb/ft)

and can also be expressed in terms of unit area as

total allowable load = 186.6 x

1 0.61 306 kg/m2 (62.7 psf)

The live load permitted to develop the maximum allowable bending

stresses in the joists is

31
live load = 306 - 23 = 283 kg/m (58 psf)

Therefore, the applied load capable of being carried by the floor

joists, which are fully stressed to maximum allowed by design

2 specification, is 283 kg/m (58 psf)

.

Total loads to Assembly 4 in the previous test series [4]

Live load

Plywood Subfloor

Wood joists

Carpet flooring

195 kg/m

9.5 kg/n/

8.1 kg/rn^

1.8 kg/m^

Total loads 214.4 kg/m (43.9 psf)

The load on one floor joist with a joist spacing of 0.61m (24 in) on center is

w = 214.4 x 0.61 = 131 kg/m (87.9 lb/ft) = 1280 N/m

and the maximum bending moment for this loading is equal to

„ wL

2 (1280) (3. 25)

2

, M = —5— =

5 = 1690 N-m (14960 m-lb)

o o

The uniform load on a joist producing this bending moment at the middle

of span can be calculated as

w = = 1736 (N/m) = 176 kg/m (118 lb/ft)

(2.79;

and the total load can also be expressed as

total load = 176 x

1

0.61

- 288 kg/m (59 psf)

32
The permissible live load, to develop the same magnitude of bending

stresses in the joists as those in assembly 4 in the previous test

series, can be obtained readily as

live load = 288 - 23 = 265 kg/m^ (54 psf)

33
Appendix B Log of General Observations During Test 1

Time

(min: sec) Events

1:20 Light glowing appearing on gypsum board ceiling

in center area.

1:40 Smoking occurring along the edges of plywood

deck, particularly on the front side.

2:08 Gypsum board paper face charring and flaking

of f

.

2:30 Smoke escaping from the perimeter of the

carpeted flooring on the unexposed side.

3:20 Small flames appear on wood sill plate along

the front edge.

4:45 Flames from sill plates around the edges of

the floor are flickering.

6:00 Smoke rising from the right rear corner on the

unexposed side is increasing.

10:50 Fire-exposed gypsum board surfaces show dull

red

.

12:00 Inside of the cavity formed by the supporting

frame for loading mechanism above test assembly

filled with dense smoke.

34
16:10 Gypsum board cracks have developed in the area centered at the quarter-point toward the east

side between the center and the north floor

joists.

16:25 Gypsum board falling from the cracked area.

16:50 One piece of gypsum board in the south-east

corner falling off.

18:16 Appreciable floor deflection occurring at the

central check point.

18:25 Gypsum board falling away at several

additional areas.

18:35 Whole fire-exposed surface of the floor

involved in flaming.

19:40 Heavy smoke coming from the east edge on unexposed side.

20:06 Burn-through in the region near the

quarter-point toward the east furnace wall

between the center and the north joists.

20:48 Gas off and test stopped.

35
Appendix C

Derivation of the Equations Used for Calculating Rate of Heat Produced

in Test Furnace

Consider a rectangular parallelpiped-shaped test furnace in which the

heat is liberated from combustion of the fuel gas with air, both being

metered separately prior to admittance to the furnace. The combustible

test specimen, installed in the ceiling-position of the furnace, and

exposed to hot furnace gas on the lower side, thermally degrades into

volatile decomposition products and char. Additional heat is released

from the gas-phase combustion of the pyrolyzates and from the solidphase oxidation of the char on the specimen surface. All products of

combustion are vented through an exhaust duct to a chimney.

In order to derive the pertinent equations for heat production rate

calculations, the following simplifying assumptions are made:

1. The furnace gases are perfectly mixed with no variations in their

composition and temperature.

2. The fuel gas introduced into the furnace and the combustible

pyrolyzates from the decomposing sample react instantaneously

with the oxygen in the air supply.

The continuity equations describing the conservation of the total mass

and the gas species around the furnace chamber may be written in the

following form:

(C-l)

(C-2)

36
where £f.W.- = FaWa + Fr Wr + F W + F W ; 1 ’1 f f p p w w

/>v.r = v.r„ + v'.'r ; J J f J P

V is the volume of the furnace chamber; p is the density of combustion

g

gases; t is time; F and W are the molar flow rate and the average

K. K. molecular weight, respectively, of the gas mixture in stream k; the

subscripts a, f, p, w and g denote the air, fuel, pyrolyzate, water and

combustion gas streams, respectively; the water stream is provided for

injecting the metered cooling water into the furnace to lower the gas

temperature when it exceed the prescribed temperature level; X_.^ is the

concentration of the gas species j in the stream k, expressed in mole

fraction; the gas species include oxygen, fuel, pyrolyzate, nitrogen,

C0„, CO, and H„0; v! and v'.' are the ratios of the stoichiometric

2’ 2 2 J coefficient of the gas species j to that of the fuel, and to that of

the pyrolyzate, respectively; r^ and r^ are the rates of disappearance

of the fuel and the pyrolyzate, respectively, expressed in moles per

unit time per unit volume of the combustion gas.

In general, the rate of change of total mass of the gases in the furnace

can be neglected when compared with the inlet and exit mass flow rates.

With this approximation, an expression for the rate of oxygen consumption due to combustion of the fuel and the pyrolyzate can be obtained

from equation ( C— 2 ) as

VEv r = (F Xn

/F - Xn ) F

0

2 a 0

2a g 02 g g

(C— 3)

Using this relationship, the rate of heat release within the furnace can be expressed by

Q = (r _ AH.. + r AH ) V f f P p

= K<f)(F XA

/F - X. ) F v

a 0

2 a g 02 g g

(C-4)

37
where c)> = (r, + r AH /AH )/(r + r v" /v’ ) and K = AH_/(v ' v) , the

f p p x i p o

2 0

2

t O

2 heat of combustion of the fuel per unit volume of oxygen consumed at

the reference state of 25°C and 1 atm; AH C and AH are the heats of

f P combustion of the fuel and that of the pyrolyzate, respectively, in

kJ/g-mole, and v is the molar volume of oxygen at 25°C and 1 atm, e.g, v is equal to an ideal gas.

v is equal to 22.414 x 10^ x (298.15/273.15) or 0.02446 m'Vg-mole for

Assuming that both the air and the combustion gas behave as ideal gases, one obtains the following expression for the rate of heat release:

Q

= K(J> [X. V T /(V T ) - X_ ] (298.15/T ) V (C-5)

0

2 a a g g a 0

2 g g g

where and are the volume flow rate and the absolute temperature

of the gas mixture in stream i.

With the assumption of perfect gases for both the fuel gas and the

pyrolyzates, the volumetric flow rate of the combustion gases in the

effluent stream can be expressed by

V

g

[V + Vj.T W£ /(TrW )+VTW/(TW)+mT v/(298.15 W )] a faffa pap pa wa a

[T W / (T W )] (C-6)

g a a g

where m = F W , the mass flow rate of cooling water injected into the w w w

furnace

.

The combustion gases exhausting from the test furnace were analyzed

after the removal of water vapor from the sample. The moisture-free

flue gas produced under fuel limited combustion in the furnace consisted

of C0

2

, CO, 0

2

, and . The concentrations of these gases, as measured

with gas analyzers, can be expressed by

38
X

C0

2 Yco2 g

/F

x

co 'Ycog/p

X? = F xn /P

0

2 g

0

2 g

y

A = 1 _ yA

y

A - yA

X

®

2

X

C0

2 X

C0

X

0

2

where P = F (Xnn + X__ + X_ ) + F X. T g C0

2 g COg 0

2 g a N2a

(C-7 )

The concentrations of CO^, CO, and 0^ in the combustion gas stream can be obtained by solving these simultaneous equations, and the water

content can be estimated based on the ratio of the moles of 1^0 produced to the moles of C0

2 and CO formed from combustion of the fuel gas

and the pyrolyzates and on the mass flow rate of cooling water injected

into the furnace. Thus,

(C-8)

Where v , v , and v are the stoichiometric coefficients of H„0, CO LU Z C0

2

, and CO, respectively, and can be determined from the general

combustion equation for the fuel gas and the pyrolyzates with air.

Since the sum of the mole fractions of 0

2

, C0

2

, CO, H^O, and N

2 gases

in the flue gas stream must be equal to unity, this results in

39
- 2/(1 + Y) (C-9)

where

Y vh

2o (xco

2 + xco

)/(v

co

2 + V C0 )

Z = 1 - m / (F W ) , and G = 298.15 V / (vT ) w g w g g g

Substituting this relation into equation (C-8) gives

xco

2 g - zx

co

2

/(1 + Y)

X

COg

= Z4/(1 + Y>

xn „ = ZX^ /(I + Y)

0

2 g o2 (C-10)

*»

2 g

= z4

2

/(1 + y)

X

H

20g

- <Y + 1 - Z)/(1 + Y >

The average molecular weight of the combustion gases can be estimated

from the equation below:

W - 32X„ + + 28X

COg + 18X

Qg + 28X,,

g °

2 g c02g

(C-ll)

The total rate of heat production in the test furnace can be calculated

from equations (C-5) and (C-10)

.

40
The quantity <J> can be expressed as

AH AH

where —7— and —rr^ are the quanties of heat produced per mole of 0_ for

°2 \

the fuel and pyrolysis products respectively. To an engineering

approximation the heat produced per mole of 0^ consumed is equal to

420 kJ/mole (13.1 MJ/kg) for most materials. Thus <j> can be taken to

be unity in equations (C-5) and (C-10)

.

41
Table 1. Descriptions of Test Assemblies, Applied Load,

and Fire Exposure Conditions

Test

No.

Furnace^

-

Modification

Structural Elements

Joist

Spacing

m in

Applied

Load

kg lb

m^ ft ^

Percentage

of

Maximum

Allowable

Stress

Fire

Exposure

Level

of

Excess

Air

Floor

Joist*

Plywood

Subf loor* 55 Thickness

mm in

Gypsum

Board

Ceiling

Thickness

mm in

1 I Wood

Joist 18 23/32

16 5/8

(Type X)

0.61 24 265 54 100

Newly

Developed High

2 I Wood

Joist 18 23/32

16 5/8

(Type X)

0.61 24 265 54 100 ASTM

E 119 High

3 I Wood

Joist 18 23/32 none 0.61 24 265 54 94 Newly

Developed High

4 I Wood

Joist 18 23/32 none 0.61 24 265 54 93 Newly

Developed High

5 I Wood

Joist 18 23/32 none 0.61 24 265 54 93 Newly

Developed High

6 Ia

Wood

Joist 18 23/32 none 0.61 24 265 54 93

ASTM

E 119

Low

7 Ia

Wood

Joist 18 23/32 none 0.61 24 265 54 93

ASTM

E 119

Low

8 lb

Wood

Joist 18 23/32

16 5/8

(Type X)

0.61 24 265 54 93 Newly

Developed Low

9 lb

Wood

Joist 18 23/32 none 0.61 24 265 54 93 Newly

Developed Low

10 lb

Steel

Joist 18 23/32 none 0.81 32 270 55 68 Newly

Developed Low

*Wood joists, southern pine, nominal 51 x 203 mm (2 x 8 in)

Steel joists, Super-C, 44.5 mm wide x 184.2 mm deep x 1.3 mm thick (1-3/4 in x 7-1/4 in x 18 ga)

Span length of all floor joists was 2.79 m (9.17 ft)

**An olefin carpet with foam rubber backing was installed over the plywood subfloor

-y-I refers to the original NBS Combination furnace. Ia and lb refer to the two successive

modifications as described in Section 2.1.

42
Table 2. Initial Weights and Total Available

Heat of Combustible Materials in Test Assemblies

Initial Weights of the Combustibles, kg

Total

Available

Test

Assembly Floor Solid Plywood Olefin Wood Wood Rim Sill Heat

,

Joists Bridging Subfloor Carpet Trim Framing Joists Plates MJ

1 33.9 8.6 72.6 13.6 0.9 13.6 45.1 30.8 4450

2 33.6 8.2 68.5 13.6 0.9 14.1 44.9 27.7 4310

3 34.9 10.0 80.3 13.2 0 0 44.4 26.3 4270

4 32.7 5.5 70.3 13.2 0 0 41.7 23.6 3860

5 34.8 8.1 66.2 13.2 0 0 42.8 24.5 3910

6 36.2 8.2 64.4 13.2 0 0 37.3 26.3 3920

7 32.9 8.2 67.6 12.2 0 0 39.7 27.0 3850

8 34.5 10.4 68.9 16.3 0.9 12.7 46.3 30.4 4550

9 30.5 10.4 67.1 15.9 0 0 39.5 32.2 4080

10 0 0 71.7 13.6 0 0 45.8 29.0 3360

43
Table 3. Summary of the Fire Endurance Times of

Floor/Ceiling Assemblies Under Furnace Fire Conditions

Assembly

No.

Time to

Time for the Unexposed

Surface to Increase

Maximum Deflection

Flame

Through

min: sec

Structural

Failure*

min : sec

Avg . Temp

139 deg C

min : sec

1-point Temp.

181 deg C min : sec

Time

min : sec

Center

Point mm

1 20:06 N. R. N. R. N. R. 20:48 47

2 34:00 35:20 35:08 34:50 35:28 331

3 6:04 6:53 N. R. 6:39 7:00 57

4 6:07 7:52 7:13 6:53 8:00 274

5 7:00 7:36 10:39 10:06 10:48 271

6 16:08 14:42 16:46 16:00 16:50 175

7 17:35 13:10 N. R. 17:08 18:10 310

8 24:22 24:59 N. R. 25:23 26:30 150

9 9:09 8:48 N. R. 9:38 10:00 95

10 4:38 2:48 5:48 4:24 5:50 231

,v No collapse of the joist, time refers to excessive deflection rate and downward bending [7].

N.R. — not reached.

44
Table 4. A Comparison of Failure Times Due to Flame Penetration

(in minutes) of Floor Assemblies Evaluated in the Test

Room and in the Fire Endurance Furance

Room

Furnace Tests

Floor

Assemblies Fire Newly Developed

Fire Exposure

ASTM E 119

Curve

Test

Low Air High Air Low Air High Air

Protected

Wood

Frame

35:08

(0.7%)*

24:22

(6.4%)

Test 8

20:06

(9.8%)

Test 1

—

34: 00

(12.8%)

Test 2

Unprotected

Wood

Frame

12:02

(0%)

9:09

(3.5%)

Test 9

6:04, 6:07

7:0**

(8.7, 9.6,

12.9%)

Tests 3, 4, 5

16:08, 17:35

(4.4, 3.8%)

Tests 6, 7

—

Unprotected

Steel

Frame

3:58

(0.9%)

4:38

(5.8%)

Test 10

— — —

*The value in the parentheses was the average concentration of oxygen in the flue gas stream

for the furnace tests and the average concentration at the top of the doorway for the room

fire tests.

**A portion of this test was run at negative pressure.

45
Table

5.

Flow

Rates

of

Air

and

Fuel

Supply,

Oxygen

Content

in

Flue

Gas,

Incident

Heat

Flux,

and

Char

Rate * m

m «H Oh kO rH in 00

rH rH Oh Oh CM oo r-» CM

1- 0) CO oo 00 <r E 1 i—i

CO co •3C d) -U o o o o o O o o o •K X Cfl £ • • • • (I • • c Pi b o o o o o o o o o e0 c CM e cu jj X E

LT> CO r^* vO ! 00 00 <r CM

•h -o

a 3 rH rH Oh Oh o CM CO

X -H O) rH £2 CM CM rH rH CM CM

ctf c S 3Sd P. I-1 e c 3 o E vD oo CO

m oo CO CM

•h cn • • • • • • • • • • •U Cd c CO m vr> Oh CM CM CO

dj

O •H

Pi U 01

so? s H H

<D i—1 o U Ph > 0) c 00 o c dJ oo oo rx Oh 00 in oo O -H Pi • • • • • • • • • CU Oh CM oo Oh CM CO kO CO m CM > i—1 o <

to

m vO

CO Pi <J* CM CO oo Oh in lO vO

S'v cu •H • • • • • • • u < rH CO CM o CO CM

X

Xw

m r- 00 Oh

CO CO

X Oh 00 1—1

CM nX CO PI CM CM kO CO CTN rH i—i

Oh 1—1 CO CU -H <r m in m o o CM CM CM e U <3 • • • • • • • X o o o o o o o o o o cu w

4~> CO pi CO o vO oo CT\ 1—1 nj CN o & i—1 CM CM CM vD CO 00 oo 00 Oh X o 0) CO CM 1 1 o CM CM co CO CN

rH 3 o o o o o o o o o O PH pLl • • • • • • • o o o o o o o o o O CD00 •K

cO Oh <r CM •K CM MD o M Pi CM co oo ON •X 00 oo m in iO> 0) •H co oo oo CM CM kO > <c • • • • 00 • • • • < o o o o o o o o o o c

-J d3 • HS cdc o cq

0) to Cfl o o o o o CO o o M E 0) 0) S3 S3 S3 Z S3 CU z z G 3 p-1 >4 >H

oi co M CP O Sh

Pi

O

PHM—I CU 0 P£ 5 S £?"• s s £

CD CO cu fH cu <U cu fcH cu <u cu CP c z CO S3 S3 z CO CO z z z

Sh CP < <£ <3 H Xwcc

CU -r- U 4-

n3 dj c o cd cd

XXX

H *r~

MM 1 1 M

M

M i—i M

XM 3 MH

Ph -r-cA

4-J CO c rH CM CO

m \D 00 Oh o cu 12 E

-4

46

*Char

rate

is

taken

to

be

the

thickness

of

the

subfloor

divided

by

its

fire

exposure

time

prior

to f

lamethrough .

*Flamethrough

was

due

to

the

opening

of

seams

rather

than

burnthrough

of

the

plywood

in

this

test.

‘-Dropped

to

0.28 m3

/s

after 4

minutes.
Table 6. A Summary of Heat Release During Fire Endurance Testing

Test

No.

Time

Duration

s

Total

Heat

Release

MJ

Average

Heat

Release

Rate

MW**

Contributed Heat

Release MJ

Fuel Structure

1 1206 2225 1.85 1954 271

2 2040 2850 1.40 2497 353

3 364 690 1.90 317 373

4 367 677 1.85 234 443

5 420 421 1.00 61 360

6 968 913* *** 0.94 1078 —

7 1055 980* *** 0.93 1142 —

8 1462 2683 1.84 2133 550

9 549 1192 2.17 820 372

10 278 365 1.31 272 93

*Low values were due to problems with the flue gas sampling system for test 6 and the air

inflow measurement for test 7.

**Including both the gas and the structure

***Quest ion able data, see page 21.

47
Figure 1. Construction details and instrumentation layouts for test assembly

no . 1

48
SECTION A-A

A

CARPET

Figure 2. Construction details and instrumentation layouts for test assembly

no . 3

49
CARPET

N

Figure 3. Construction details and instrumentation layouts for test assembly

no . 10

50
3050

51

Figure

4.

Layout

of

steel

blocks

distributed

uniformly

over

the

top

of

the

test

assembly
o

M

.2

w

@

E

%3

00

52

Figure

5.

Floor

plan

of

test

furnace

showing

locations

of

thermocouples

and

pressure

probes
TIME

m

MIN

o o o o o o

o o o a a o o o o a O O o o a

o o o o o o o o o a O o o o m eg o 05 ID r* (0 ID m (SJ o — 3aruva3dW3i svo

53

FIGURE

SA

-

AVERAGE

FURNACE

GAS

TEMPERATURE

MEASURED

WITH

FAST

RESPONSE

THERMOCOUPLES
O O O O O Q

m

id2

o o o o o o O a a a o o a O a

o o o o o o o a o o o o o O

T fO CM —• o 05 CD r* w i/j tn CM o «* 3ymvb3dW3i svo

54

FIGURE

6.5

-

AVERAGE

FURNACE

GAS

TEMPERATURE

MEASURED

WITH

FAST

RESPONSE

THERMOCOUPLES
TIME

*<

MIN

55
oOOOOQOOOOOOOOOO o o o o a

st—

0 «» 38niva3dW3i SVO

56

FIGURE

7

A

-

AVERAGE

FURNACE

CAS

TEMPERATURE

MEASURED

WfTH

ASTM

THERMOCOUPLES
o?

o o o O o a o o a a a o o o a o o o o o a o o o o a o o o o o

lO fr> eg a O) © r* to © (O N «— 0 — 3dmva3dW31 svo

I ODN

K

3

57
0 — 3bniva3dW3i SVD

I qPv

0£ 3

E

58
TIME

•**

MIN

m — oo>flor*u>uj'r(ncM — o

OOOOOOOQOO «/ftu —. 3iyy MOU 3WmOA

59

FIGURE

8.A

~

AIR

FLOW

RATE

TO

THE

FURNACE
TIME

«**

MIN

«si —> o o «o r* ld <n c>» — o

B/fuj .« 31VW MOU 3WmOA

60

FIGURE

0.B

-

AR

FLOW

RATE

TO

THE
m

»

00o

r*o

COo

too<na

CMa §

®/,uj

3 0 0

•« 3ivy MOU 3WmOA

61

FKJURE

9A

~

FUEL

FLOW

RATE

TO

THE
TIME

in

MIN

ear-iysusi'M-mcM^o ooooooooo • « © 0 0 I • • •

CM

O

a

©

oo

m

a

CM

oa

o>

a

o

QO

O

on

a

»/rw ««« 3ivy M01J 3WmOA

m

:*ft—

62

FIGURE

9.B

-

FUEL

FLOW

RATE

TO

THE

FURNACE
80*0

63

FIGURE

9.C

-

FUEL

FLOW

RATE

TO

THE

FURNACE
TIME

w

MIN

a i/> o in a

<N — - D O

NOI13VH3 non ••• N0I1VU1N33N00 N39AX0

64

FIGURE

10.A

-

OXYGEN

CONCENTRATION

IN

FLUE

GAS

STREAM
TIME

*«

MIN

o

CSI o ino

in a BSCSa

3f

65

FIGURE

10.0

-

OXYGEN

CONCENTRATION

IN

FLUE

GAS
TIME

«**

MN

O O 1/3 O

CSJ « — O

NOliOVHJ now ••• N0liVMiN30N00 N30AX0

66

FIGURE

10.C

-

OXYGEN

CONCENTRATION

IN

FLUE

GAS
TIME

•**

MIN

o o o

OOQQOOOOOOQOO o)r»u>«r» — —

I (nLOP'OJ I I I !»*<—< — ww—

• I I od ••• 3anss3dd Diivis

67

FIGURE

11*

-

AVERAGE

UPPER

FURNACE

STATIC

PRI
o

68

FIGURE

1

1.0

-

AVERAGE

UPPER

FURNACE

STATIC

PRESSURE
TIME

*«

MIN

O LO

69

FIGURE

11.C

-

AVERAGE

UPPER

FURNACE

STATIC

PRESSURE
TIME

***

MIN

O Q © O O

O O © Q ©

!

g0=

70

FIGURE

1ZA

-

TOTAL

RATE

OF

HEAT

RELEASE

IN

FURNACE
TIME w

MIN

71

FIGURE

12.B -

TOTAL

RATE

OF

HEAT

RELEASE

IN

FURNACE
TIME

***

MIN

o a o o o

o o o o o u

M ••• 3SV313W 1V3H JO 31VH

72

FIGURE

12.C

-

TOTAL

RATE

OF

MEAT

RELEASE

IN

FURNACE
o o o o o

o o o o o o

m

»

*-

73

FIGURE

13.A

-

COMPARISON

OF

RATES

OF

HEAT

RELEASE

IN

FURNACE

FOR

TESTS

1

AND 2
o a o o o

o o o o © o

o 10 o us o ifl w W M «* «“« M'l ••• 3SV313H 1V3H JO 31V8

74

FIGURE

13.B

-

COMPARISON

OF

RATES

OF

MEAT

RELEASE
TIME

MIN

g»—

o

o

CO o

(D

Csj o O O o o o a o O o o o a a

(0 CM o oo (0 CM o 00 (0 CM

<SJ CM CM CM —> «

tLU/M>1 «" xmj 1V3H

75

FIGURE

14-.A

-

AVERAGE

TOTAL

HEAT

FLUX
TIME

•**

MIN

o o o o o o

8lu/m>1 *« xmj 1V3N

*

76

FIGURE

14.8

-

AVERAGE

TOTAL

HEAT

FLUX
TIME

MIN

o o o o o o

«

'i—

77

FIGURE

14.C

-

AVERAGE

TOTAL

HEAT

FLUX
TIME

MIN

XfTTJ 1V3M

78

FIGURE

14J)

-

AVERAGE

TOTAL

HEAT

FLUX
TIME

m*

MIN

o

o<r> O

m

CM a

o

CM

fUJ/MM

o

if) a

a

*•« Xfl'IJ 1V3H 1N30I0NI

if) a

79

FIGURE

13.A

-

COMPARISON

OF

CALCULATED

AND

MEASURED

HEAT

FLUX

INCIDENT

AT

SOUTH

WALL

FOR

TEST

1
TIME

MIN

o o o o o

(T> Cg CVJ — —

,UJ/M xrru 1V3H LN30I0NI

«

»

80

FIGURE

15.B

-

COMPARISON

OF

CALCULATED

AND

MEASURED

HEAT

FLUX

INCIDENT

AT

EAST

WALL

FOR

TEST

1
81

FIGURE

15.C

-

COMPARISON

OF

CALCULATED

AND

MEASURED

HEAT

FLUX

INCIDENT

AT

SOUTH

WALL

FOR

TEST 2
O O O Q O

3

t*-

82

FIGURE

15.D

-

COMPARISON

OF

CALCULATED

AND

MEASURED

HEAT

FLUX

INCIDENT

AT

EAST

WALL

FOR

TEST 2
83

WALL

FOR

TEST 8
TIME

MIN

o i/> o in a

<si — — o a

° NOUDVyj 310W ••• NOI1VM1N30NOO SVO °

84

FIGURE

1«>

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST

1
TIME

•«

MIN

NOUDVbJ JIOW — NOLLVblN30NOO SVO

85

FIGURE

16.B

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST 2
TIME

MIN

o id o to a

cm — — © a • « • e •

o o a o o

ov-» CM

a

a

«

oa

1/2

a

CM

ao

o>

a

<0

o

oart

a

m

2P

NOUDVUJ J10W ••• NOUVH1N30NOD SVO

86

FIGURE

16.C

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST 3
nm

3

m

a W O W O

O

CM U) ino

a

o• o

NOUDVad 310W ••• NOI1VH1N30NOO SVO

87

FIGURE

15.D

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST

4
o us o as © CM — — O O

o to q as q

cm — — © o • • 8 » • © O O © ©

N0U3VHJ Flow «**« N0U.VbJ.N30 NOD SVO

88

FIGURE

16.E

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST 5
TIME

•**

MIN

O LO O LO o

CM — — O O

o o

NOilDVyj now — NOLLVmN30NOO svo

89

FIGURE

1®J

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST

6
O U3 O ID Q w — — o a

O O © © Q

NOUDVEJ 310W NOUV«1N30NQO SVO

90

FIGURE

15.G

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST 7
TIME

"*

MIN

0 1/5 0 1/5 0

CM —> — O O

e o o o o

NOUDVbJ J10W ••• NOLLVH1N30NOD SVO

91

FIGURE

l«Ji

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST a
O 1/3 O 03 ©

css — — © ® 9 * O f 0 a»-*

€SS

o

Q

OD

Oa

m

o

a

CM

Oa

m

a

co

o

•v- CF)'

a

9)»

ItNOliDVHJ 310W ••• NOLLVM1N30N00 SVO

92

FIGURE

1&I

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST 9
TIME

MIN

O U) O 1/5 O

cst — — O o • • • • • o o o o o

Nouovaj now ••• nouvhln3onoo svo

93

FIGURE

16J

-

EXHAUST

GAS

CONCENTRATIONS

FOR

TEST

10
&0 o o o o Q o a o o © u? w Cvs «-* Q

(8®|r»or 6**0l) no *** 3SVTQW 1V3H

94

FIGURE

\7A

-

TOTAL

HEAT

RELEASE

AND

HEAT

RELEASE

ST

FUEL

FOR

TEST

1
TIME

«<•*

MIN

o o o o o o

95

FIGURE

17.B

-

TOTAL

HEAT

RELEASE

AND

HEAT

RELEASE

BY

FUEL

FOR

TEST 2
o o © o o ©

(Minof 6**0 0 PO «** 3SW3T3W 1V3H

96

FIGURE

17.C

-

TOTAL

HEAT

RELEASE

AND

HEAT

RELEASE

BY

FUQ.

FOR

TEST 5
TIME

«**

MIN

o o o o o o

LO *C CO CM —i O

(•inof 6«0l) no w* 3SVJT3U 1V3H

97

FIGURE

17D

-

TOTAL

HEAT

RELEASE

AND

HEAT

RELEASE

BY

FUEL

TOR

TEST

4
98

FIGURE

17.E

-

TOTAL

HEAT

RELEASE

AND

HEAT

RELEASE

BY

FUEL

FOR

TEST 5
TIME

•'*

MIN

o

**••••

o o o o o

if) <n cm o

(g®inof 6-01) TO 3SVTI3U 1V3H

99
o o o o o o 0 Q 0 Q 0 0

(i©in©f s««ol) ro *** 3SV3TQy 1V3W

i8—

100

FIGURE

I7.G

-

"TOTAL

HEAT

RELEASE

AND

HEAT

RELEASE

BY

FUQ»

FOR

TEST

7
TIME

*»*

MIN

o o o o o o • • • • I • lP v n cm —* o

(a*|nof S.-oi) PO «• 3SV3T3U 1V3W

101

FIGURE

17.H

-

TOTAL

HEAT

RELEASE

AND

HEAT

RELEASE

BY

FUEL

FOR

TEST 5
o o o a © o • O 9 Q « 0

(s®|nof s«»Ol) ro ••• 3SVJT3U i¥3M

102

RGURE

1

7

J

-

TOTAL

MEAT

RELEASE

AW

HEAT

RELEASE

BY

¥WBl

FOR

TEST

9
TIME

MIN

O o o o o o

'* (T) CM — O

(8*|nof 6**0 1 ) no *•* 3SVJT3y 1V3W

103

FIGURE

17J

-

TOTAL

HEAT

RELEASE

AND

HEAT

RELEASE

BY

FUEL

FOR

TEST

10
o

D

esj a

a

a

a

a

a

a

a

a

o

o

s

S3 ©O

a

a

o

G ©O

©

s

©•3en

a

a

Sri

CV

« _ » S e- a « © ...

o

s

104

FIGURE

IB

-

PROPOSED

FIRE

EXPOSURE

CURVE
0 «* 3dniVU3dN31 svo

105

FIGURE

19

-

COMPARISON

OF

THERMOCOUPLE

TYPES

AT

CENTER

OF

FURNACE

FOR

TEST

8
N BS°1 14A (REV. 2-80

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO. NBSIR 82-2488

2. Performing Organ. Report No. 3. Publication Date May 1932

4. TITLE AND SUBTITLE

Fire Endurance Tests of Selected Residential Floor Constructions

5. AUTHOR(S)

Jin B. Fang

6. PERFORMING ORGANIZATION (If joint or other than NBS. see in struction s) 7. Contract/Grant No. national bureau of standards

DEPARTMENT OF COMMERCE 8. Type of Report & Period Covered

WASHINGTON, D.C. 20234

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State, ZIP)

Sponsored in part by:

U. S. Department of Housing and Urban Development

Washington, DC 20410

10. SUPPLEMENTARY NOTES

1 Document describes a computer program; SF-185, FIPS Software Summary, is attached

11. ABSTRACT (A 200-word or less factual summary of most significant information . If document includes a significant

bi bl iography or literature survey, mention it here) A series of 10 load-bearing, wood- and steel-framed residential floors was evaluated

for structural fire resistance in a fire endurance furnace. Nine wood-frame and one

light gauge steel-frame, protected and unprotected floor/ceiling assemblies, each

measuring 3.05 x 2.44 m in size, were exposed from the underside to either the newly

developed high-intensity, short-duration fire exposure or the standard ASTM E 119

time-temperature curve. The fire endurance time based on the passage of flames to the

unexposed face of the floor with unprotected wood joists varied from 6 to 9 minutes

under the newly developed fire exposure and 16 to 18 minutes subject to the standard

ASTM fire. Under the identical fire exposure, the exposed steel-framed floor failed

in approximately 4.5 minutes compared to 9 minutes for the unprotected wood-frame

floor. The wood floors evaluated in the test furnace had a shorter fire resistance

period in comparison with those tested previously under room fire conditions probably

due to faster charring rates and additional heat contribution from the burning of

combustible materials in the structure with the excess air present in the furnace.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) Fire endurance; fire tests; flame through; floors; furnace tests; joists; steel; wood

13. AVAILABILITY 14. NO. OF

PRINTED PAGES

[Xj Uni imited

| | For Official Distribution, Do Not Release to NTIS 113

1 Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

15. Price 20402.

[X] Order From National Technical Information Service (NTIS), Springfield, VA. 22161 $12.00

USCOMM'DC 6043-P80

1II/