NBSIR 73-165

^

Fire Endurance Test on a Steel Tubular

Column Protected with Gypsum Board

B. C. Son

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington. D. C. 20234

April 1973

Final Report

Prepared for Office of Research and Technology

Department of Housing and Urban Development

Washington, D. C. 20410

NBSIR 73-165

FIRE ENDURANCE TEST ON A STEEL TUBULAR

COLUMN PROTECTED WITH GYPSUM BOARD

B. C. Son

Center for Building Technology

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

April 1973

Final Report

Prepared for Office of Research and Technology

Department of Housing and Urban Development

Washington. D. C. 20410

U. S. DEPARTMENT OF COMMERCE. Frederick B. Dent. Secretary

NATIONAL BUREAU OF STANDARDS. Richard W. Roberts, Director

Fire Endurance Test

on

A Steel Tubular Column Protected with Gypsum Board

by

B. C. Son

Building Fires and Safety Section

Center for Building Technology

ABSTRACT

As a part of the evaluation of housing systems for Operation

BREAKTHROUGH a standard fire endurance test was performed at the National

Bureau of Standards on a load-bearing steel column construction for use

in single-family attached and multifamily low-rise housing. The

test method was generally in accord with the requirements of ASTM E 119,

Standard Methods of Fire Tests of Building Construction and Materials,

for a loaded column. The applied load was 7110 pounds per column and

the test results are valid only for columns of such construction loaded

at or below the stress level developed by this loading.

The 3 in. x 2 in. x 3/16 in. rectangular hollow tubular steel column

was protected with two layers of gypsum board.

The fire endurance of the column assembly was established at 59

minutes, when structural failure occurred.

Key Words: Fire endurance; fire test; housing system; multifamily

housing; Operation BREAKTHROUGH; single family attached

housing; steel tube column

i
TABLE OF CONTENTS

Page

ABSTRACT i

1.0 INTRODUCTION 1

2.0 CONSTRUCTION 1

2.1 Specified Fastener Schedule 2

2.2 Actual Fastener Schedule 2

3.0 INSTRUMENTATION 2

4.0 DESCRIPTION OF TEST 3

5.0 4.1 Loading 3.

4.2 Furnace Temperature 4

4.3 Test Evaluation 4

1. Loaded Column 4

2. Unloaded Column 4

5.0 TEST RESULTS 4

6.0 DISCUSSION 5

TABLE I 7 Observation During the Test

APPENDIX I 8

Load Calculation

APPENDIX II 10

SI Conversion Units

FIGURES
1.0 INTRODUCTION

A standard fire test was conducted to measure the fire endurance of

a rectangular hollow tubular steel column having a protective covering

of two layers of gypsum board. The test was performed at the Fire Test

Laboratories of the National Bureau of Standards, Washington, D.C.

The column for use in single-family attached and multifamilv lowrise housing was subjected to the design load of 7110 lbs throughout the

test. The fire test followed the requirements for columns of Standard

Methods of Fire Tests of Building Construction and Materials, ASTM

E 119- .

2.0 CONSTRUCTION

Figure 1 shows the column assembly in place prior to the fire test.

The column assembly was made up of a 3 in. x 2 in. x 3/16 in. hot rolled

rectangular structural (ASTM Grade A-36) steel tube protected by two

layers of gypsum board. The underlayer was 3/8 in. regular gypsum board

and the face (fire-exposed) layer 1/2 in. type C. The fire-exposed face

was plastered with 1/8 in. thick joint compound. At the top and the bottom of the column assembly a 6 in. x 9 in. x 3/16 in. thick bearing plate

was attached with a continuous fillet weld around all sides of the column

leaving an overall column length of 10 ft. 8 in. (including the 3/16 in.

bearing plates). Each bearing plate had four 1/2 in. diameter bolt holes

located in the corners of the plate 1 in. from each edge. The measured

weight of the column assembly was 120 lbs. For the specimen tested the

—^ Standard Methods of Fire Tests of Building Construction and Materials , American Society for Testing and Materials Designation E 119-71,

available at 1916 Race St., Philadelphia, Pa. 19103.

1
metal fastener schedule for the gypsum boards varied from the specified

fastener schedule shown on design drawing provided by Housing System

Producer (HSP)

.

2. 1 Specified Fastener Schedule

The under layer of 3/8 in. regular gypsum board was to be attached

with 1 in. long type S-12 bugle head screws along the center of each

side at 16 in. centers. The face layer of 1/2 in. type c gypsum board

was to be attached with two 1-5/8 in. long S-12 bugle head screws at

each corner and at 16 in. centers vertically. The four corners were

secured with corner reinforcement (ECONO standard dur-a-bead) which was

to be attached with 5/16 in. drywall nails at 24 in. centers. The construction detail of the specimen with specified fastener schedule is

shown in Figure 2.

2 . 2 Actual Fastener Schedule

The fasteners used in the test consisted of 1 in. self drilling

bugle head metal screws on the underlayer of gypsum board and 2-1/4 in.

self-drilling Phillips recessed flat head metal screws. Both were spaced

approximately at 16 in. centers along the center line of each side on the face

layer. The corner reinforcement was crimped for holding into the gypsum

boards. The photograph in Figure 3 shows the fastening on the actual

column and comer reinforcement.

3.0 INSTRUMENTATION

The instrumentation consisted of thermocouples, loading ^ack and

deflection indicator. A total of 15 Chromel-Alumel (type K) thermocouples

2
was installed on the steel column face at four levels as indicated by

the position B, N, M, and T in Figure 4. Three thermocouples were located

at level T and four thermocouples at levels B, N, and M. The thermocouples were attached with sheet metal screws to the column prior to

attaching the two layers of gypsum boards. The thermocouple wire was wound

twice around each screw with the beaded junction under the head of screw.

The lead wires were run underneath the bottom layer of gypsum board, up to

the underside of the top bearing plate. Care was taken to avoid damaging

the thermocouple wires with the screws used for attaching the gypsum boards.

The temperatures of the thermocouples were printed out at 1 minute

intervals on a data logger from which they were punched onto cards for

processing and plotting by computer.

The vertical deflection of the column assembly during the test was

measured by a dial indicator gage, which was placed under the bottom of the

loading frame. Figure 4 shows the furnace and loading equipment with the

column specimen in place.

4.0 DESCRIPTION OF TEST

4.1 Loading

Because of the furnace construction, the test specimen was fabricated

longer than the design column length. The required load was reduced

2/

to 7,110 lbs in accordance with the column formula in the AISC- Manual

of Steel Construction. The loading calculation is shown in Appendix I.

The load was applied through a hydraulic jack at the bottom of the

specimen.

21— Manual of Steel Construction, 7th edition, American Institute of Steel

Construction, 101 Park Avenue, New York, New York 10017.

3
4.2 Furnace Temperature

The temperature inside the furnace was measured by 12 standard

Chrome1-Alumel thermocouples enclosed in 1/2 in. wrought iron pipes with

closed ends placed at various heights around the column. The furnace temperature was constrained to follow the standard ASTM E 119 time-temperature

curve by manual control of gas flow to the burners. The actual furnace

time-temperature curve is shown in Figure 5.

4 . 3 Test Evaluation

The fire endurance of a column assembly according to the criteria

of ASTM E 119 is as follows:

1. For Loaded Column

The test is regarded as successful if the column sustains the

applied load during the fire endurance test for a period equal to that

for which clsssification is desired.

2. For Unloaded Column

The test is regarded as successful if the transmission of heat

through the protection during the period of fire exposure for which classification is desired does not raise the average (arithmetical) temperature

of the steel at any one of the four levels above 1000°F (538°C) or does

not raise the temperature above 1200°F (649°C) at any of the measured

points.

5.0 TEST RESULTS

The log of test observations is given in Table I.

The average and the 'maximum temperature rise of the column thermocouples during the test are shown in Figure 6. At one hour, the column

4
temperatures ranged approximately from 450°C to 850°C, with an average

of 610°C, and a maximum single-point of 830°C. The vertical deflection

was measured at the bottom of the loading rig and is shown in Figure 7.

Structural failure of the column occurred at 61 min:50 sec. when the

column could not sustain the applied load, as shown in Figure 7. The

corrected time of the structural failure, according to the standard correction formula in ASTM E 119 which is based on the comparison of the

areas under the actual time-temperature curve and the standard curve, was

59 minutes. Inspite of the applied load, the length of the column expanded

due to the furnace heat. Just prior to the failure, the length of the

column had expanded approximately 0.8 inches.

Figure 8 shows the conditions of the column at the end of the test

and the bowing of the column near the bottom.

6.0 DISCUSSION

Since the test was performed under the design load, the E 119

criterion for fire endurance was only based on sustaining the applied

load. Therefore, the temperature readings of the steel are provided

information only for evaluating the column protection during the

test. As shown in Figure 6, the time to an average temperature rise of

538°C and a maximum temperature rise of 649°C were 57.5 minutes and 53.5

minutes, respectively.

As mentioned in "2.0 Construction", the fastener schedule on the

column assembly tested was different from that shown on design drawings

provided by the HSP. In fire endurance tests, the fastener schedule can

sometimes have a large effect on the fire performance of an assembly.

5
A load of 7110 lbs was applied to the column. The test result

should be applied only to columns of such construction loaded to develop

stresses not exceeding those developed in this test

.

6
TABLE I

OBSERVATIONS DURING THE TEST

Time Observations

MinrSec

0:00 Start test.

1:00 Paper burning on the exposed gypsum board.

2:00 Completion of paper burning.

4:00 Green flame from paint burning on the corner reinforcement.

5:00 The corner angle reinforcement beginning to separate.

7:30 Gypsum boards on the exposed surface starting to buckle

horizontally and vertically.

10:00 Near the mid-height of the column small pieces of gypsum

board on the north and east side are beginning to fall in.

12:00 The corner angle reinforcement has been separated and is

hanging down. (Figure 9).

28:00 The corner joints on the south and east side of the gypsum

boards have opened up about 3/8 inch. The south gypsum

boards are buckling a little and this is slowly increasing.

45:00 The gypsum board on the south face has separated about one

foot. Horizontal cracks are observed on the under layer

of gypsum board on south side. On the north side the separation of the face gypsum board has increased to about 6 inches.

(Figure 10)

48:00 On the north face there was a crack about three feet from the

bottom of the specimen. A piece of gypsum board from the

face layer about 1 foot high has fallen down.

55:00 On the east side the face gypsum board has come off and the

under layer is now exposed.

56:00 The underlayers of gypsum board have started to come off and

the steel face is exposed at the bottom of the column.

59:00 The column is starting to buckle.

61:50 Load failure.

(59:00)*

* Corrected time according to the atandurd correction formula Is AST'M E 119.

7
APPENDIX I

Load Calculation For Increased Column Length

Prototype Column

Structural Rectangular Steel Tube 3 in. x 2 in. x 3/16 in.

2 Area: A = 1.644 in.

Radius of Gyration: r = 0.77 in.

Design Load: P =14.3 KIPS

Length: ^d ^ ^ ^ "

L^/r = 90/0.77 = 117

a Axial stress permitted in the absence of bending moment

= 10.91 KSI From Table 1-36 in AISC (Manual of

Steel Construction, 7th Edition)

The allowable load to produce the working stress

P ^ = A X Fj = 1.644 x 10.91 = 17.95 KIPS

ad d

The percentage of design load to allowable load

14.3

17.95

X 100 = 79.7%

Fire Test Column

Same rectangular tube with length

L^ = 10 ft. 8 in. = 128 in.

V-^ = or -

Axial stress permitted in the absence of bending moment

F^ = 5.42 KSI From Table 1-36 in AISC (Manual of

Steel Construction, 7th Edition)

The allowable load to produce the working stress

P^ = A X F^ = 1.644 X 5.42 = 8.91 KIPS

8
I

The load applied to the test column

Paf = 8.91 x^f^= 7.11 KIPS

9
APPENDIX II

SI Conversion Units

In view of present accepted practice in this country in this

technological area, common US units of measurement have been used

throughout this paper. In recognition of the position of the United

States as a signatory to the General Conference of Weights and Measurements which gave official status to the metric SI system of units in

1960, we assist readers interested in making use of the coherent system

of SI units by giving conversion factors applicable to US units used

in this paper.

Length

1 in = 0.0254 meter

1 ft = 0.0348 meter

Mass

1 lb = 0.45 kilogram

Force

1 kip = 4448 newton

Stress

1 psf = 47.88 newtou/meter^

Temperature

Temperature in °F = 9/5 (temperature in °C) +32°F

JO

(8)-l-5/8" TYPE S-12

BUGLE HEAD SCREWS

at 16" CTRS.

1/2" TYPE "C

GYP BOARD

(4)-l"TYPE S-12

BUGLE HEAD SCREWS

at 16" CTRS.

3/8 GYPSUM

BOARD

3 x2 X3/I6 HOT ROLLED

STRUCTURAL STEEL

TUBE COLUMN

DRYWALL NAILS 6/16"

at 24" CTRS. (TYP.)

DUR-A-BEAD CORNER

REINFORCEMENT (ECONO,

STANDARD) TYP. 4 CORNERS

Figure 2. Section detail of the column with specified fastening (not tested)

12
Figure 3 Steel tube and its section

with nailing, corner reinforcement,

and two types of screws used.
TENSILE RODS

t-H COLUMNS

8" M.5*

OBSERVATION

WINDOW

MEASUREMENT FOR

Figure 4. Furnace and loading eaulomant with tvolcal column in, olace.

14
TIflEinlNUTE)

Figure 5 Average Furnace Temperature Compared With Standard ASTM E 119 Curve Crest-495)

15
laoo,

80Q_

CD 600_

UJa

a.

® RVC. TCflP. RT ANY LCVCL

A RVE TCPIP. RT LEVEL T TEflP. RT LEVEL M

TEnr. RT LEVEL N

TEflP. RT LEVEL B

TEfir. RT RNY THERflOCOUrLE

4- RVE

X RVE ^ RVE ^ riRX

S-^« °r q pFrryTPP tjn^IT F^p AVr . TEMP. RT.SK

AOO.

200_

0

1—

10 30 40 1^ 60

. T I f1E( MINUTE) Figure 6

Average Temperature Rise On The Steel Surface At Any Level. At Level T

And B And Maximum Temperature Rise At Any Thermocouple (Hest-^SS)

16

V.

M. N,
1.00

COLUMN DEFLECTIONS

TIME, MIN.

Figure 7. Vertical deflection of the column during the test.

17

Figure 9. Note the corner reinforcement separating from the column.

Test time of 12 minutes.

FORM NBS-114A (1-71)

BIBLIOGRAPHIC DATA

SHEET

1 PIfRI JfA rrOM OR RPPOPT MO

NBSIR 73-165

2» Gov t Accession

No.

3. Recipient s Accession No.

A TIT 1 P ANin ^sURTITl F Fire Endurance Test on a Steel Tubular Column Protected

With Gypsum Board

5. l-*ubiication Date

7. AUTHOR(S)

Byung Chan Son

8. Performing Organization

NBSIR 73-165

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Taslc/Work Unit No. 4600437

11. Contract/Grant No. IAA-H-16-70

12. Sponsoring Organization Name and Address

Department of Housing and Urban Development

Washington, D.C. 20410

13. Type of Report & Period

Covered

Final

14, %>onsoring Agency Oodft

15. SUPPLEMENTARY NOTES

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

bibliography or literature survey, mention it here.)

As a part of the evaluation of housing systems for Operation BREAKTHROUGH a standard

fire endurance test was performed at the National Bureau of Standards on a load-bearing

steel column construction for use in single-family attached and multifamily low-rise

housing. The test method was generally in accord with the requirements of ASTM E 119,

Standard Methods of Fire Tests of Building Construction and Materials, for a loaded

column. The applied load was 7110 pounds per column and the test results are valid

only for columns of such construction loaded at or below the stress level developed

by this loading.

The 3 in. X 2 in. X 3/16 in. rectangular hollow tubular steel column was protected

with two layers of gypsum board.

The fire endurance of the column assembly was established at 59 minutes, when

structural failure occurred.

17. KEY WORDS (Alphabetical order, separated by semicolons)

Fire endurance; fire test; housing system; multifamily housing; Operation BREAKTHROUGH;

single family attached housing; steel tube column

18. AVAILABILITY STATEMENT

^

UNLIMITED.

[ J FOR OFFICIAL DISTRIBUTION. DO NO I' Klil.lASi: TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SHt URirY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Prii c

USCOMM-OC 66244.P71