Fire performance of houses

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Fire performance of houses - Phase 1 study of basement fires with unprotected floor assemblies

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Phase-1 Study of Basement Fires with

Unprotected Floor Assemblies

June 16th_{, 2010}

Joseph Su

(3)

Fire Performance of Houses – Outline

Background

Objectives

Experimental Program

(4)

Advent of new materials and innovative

products/systems used in construction of houses

Need to better understand performance and

impact on the life safety of occupants under fire

conditions

CCBFC and CCCME requested NRC to

undertake research

(5)

Objectives

To better understand

• the factors that affect the life safety of occupants • the impact of residential construction products and

systems on life safety of occupants

(6)

Experimental Program

Multi-phase studies – Fire Performance of Houses Phase I – basement fires and unprotected floor

assemblies over basement

• To study impact on the ability of occupants on upper storeys to escape in the event of a basement fire

– fire development

– smoke movement & tenability conditions

– structural integrity of unprotected floor assemblies • To determine the sequence of fire events

– fire initiation

– smoke alarm activation

– onset of untenable conditions on upper storeys – failure of floor assembly above the basement

(7)

Test Facility

A full-scale test house simulating a two-storey

detached single-family house with a basement

(8)

Basement

Thermocouples CO / CO2 / O2 Smoke Alarms Air Velocity Pressure Video Legend

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Basement Ceiling – Unprotected Assemblies

Solid wood joists Wood I-joists (LVL flanges) Wood I-joists (FJL flanges)

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First Storey

Legend Thermocouples CO / CO2 / O2 FTIR Smoke Alarms Smoke Density Air Velocity Pressure Video

State of doorway to basement:

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First Storey

Loading on Test Floor Assembly

OSB Subfloor

0.95 kPa imposed load (20 psf, i.e. ½ NBC design load) Self-weight of test floor assembly

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Fire Scenarios

Basement NW quadrant. Time (s) 0 200 400 600 800 1000 T e m per atur e ( ºC) 0 200 400 600 800 1000 FS-1 UF-01 UF-03 UF-04 UF-05 UF-06 UF-06R UF-06RR UF-07 Basement NW quadrant Time (s) 0 200 400 600 800 1000 T e m per atur e ( ºC) 0 200 400 600 800 1000 FS-4 UF-02 UF-08 UF-09

open basement doorway closed basement doorway

Temperatures in basement fire room at 2.4 m height

Relatively severe, fast-growing fire in the basement

Very reproducible fire exposure

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Measurements and Analysis

Smoke alarm responses

Estimation of time to untenable conditions

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Smoke alarm location Basement fire room 1st _storey ₂nd _storey corridor 2nd _storey bedroom (open) 2nd _storey bedroom (closed) type I P 2 I 3 P 4 I 5 P 6 I 9 P 10 I 7 P 8

Tests with open basement doorway

Test UF-01 - 40 75 85 125 135 140 150 200 205 Test UF-03 - 48 58 73 123 133 143 143 218 228 Test UF-04 - 30 65 85 115 130 160 225 230 250 Test UF-05 - 45 40 55 130 145 155 165 245 275 Test UF-06 - 45 75 85 115 125 130 200 230 255 Test UF-06R - 38 58 78 113 123 138 163 198 223 Test UF-06RR - 43 73 78 128 138 143 153 223 248 Test UF-07 - 50 40 55 110 130 130 145 190 210

Tests with closed basement doorway

Test UF-02 - 42 72 97 172 182 212 n.a. 427 541

Test UF-08 - 50 85 95 205 205 220 210 515 515

Test UF-09 - 44 79 89 179 179 209 204 479 459

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Tenability Analysis

Untenable conditions

• Smoke obscuration (optical density measurements)

• Toxic, asphyxiant gases (CO/CO₂/O₂measurements)

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Tenability Analysis – gas measurements

Time (s) 0 100 200 300 400 500 Concentration (%Vol) 0 5 10 15 20 CO₂ CO O₂ Time (s) 0 100 200 300 400 500 Concentration (%Vol) 0 5 10 15 20 CO₂ CO O₂

closed basement doorway open basement doorway

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Tenability Analysis – temperature measurements

closed bedroom 200 400 600 800 open bedroom 200 400 600 800 2nd storey corridor 200 400 600 800 1st storey SW quadrant Time (s) 0 100 200 300 400 500 0 200 400 600 800

UF-06R _{closed bedroom}

200 400 600 800 open bedroom 200 400 600 800 2nd storey corridor 200 400 600 800 1st storey SW quadrant Time (s) 0 200 400 600 800 1000 0 200 400 600 800 UF-09 T emperature (ºC) T emperature (ºC)

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Tenability Analysis – optical density measurements

Time (s) 0 200 400 600 800 1000 Optical Density (m -1 ) 0 2 4 6 8 1.5 m above floor 0.9 m above floor Time (s) 0 200 400 600 800 1000 Optica l De nsity (m -1 ) 0 2 4 6 8 1.5 m above floor 0.9 m above floor

closed basement doorway open basement doorway

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Tenability Analysis – estimation of time to

untenable conditions

Depending on many factors

• Fire characteristics and house geometry

• Endpoints for tenability analysis (incapacitation used)

• Occupant characteristics, activities, susceptibility,

thresholds/tenability limits

• Each occupant likely to have a different time

Tenability limit/threshold values used

• Smoke obscuration: optical density (OD) = 2 m-1

• CO/CO₂ or heat exposure: fractional effective dose approach

–FED = 1 for a healthy adult of average susceptibility –FED = 0.3 for a more susceptible person

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Time (s)

0 200 400 600 800 1000 1200 1400

OD > 2 m-1

onset of untenable conditions FED = 0.3

smoke alarm activation

initiation of fire 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 FED = 1.0

Solid wood joist

Wood I-joist A

Steel C-joist

Metal-plate wood truss

Wood I-joist B

Metal web wood truss

open

basement

doorway

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Time (s)

0 200 400 600 800 1000 1200 1400

OD > 2 m-1

initiation of fire 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 FED = 1.0

Solid wood joist

Wood I-joist A

Steel C-joist

Wood I-joist B

open

basement

doorway

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OD > 2 m-1

initiation of fire 0 200 400 600 800 1000 1200 1400 FED = 1.0 Open 0 200 400 600 800 1000 1200 1400 Closed 0 200 400 600 800 1000 1200 1400 Open 0 200 400 600 800 1000 1200 1400 Closed (s) 0 200 400 600 800 1000 1200 1400 Open 0 200 400 600 800 1000 1200 1400 Closed

a) Solid wood joist

b) Wood I-joist A

c) Metal web wood truss

(s) (s) Comparison: open vs closed basement doorway

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OD > 2 m-1

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OD > 2 m-1

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OD > 2 m-1

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Structural Response of Test Assemblies

TCs under insulated pads on subfloor Te mpe rature (ºC) 0 100 200 300 400 500 600 700 800 Flame sensors at subfloor T&G joints

Volt s 0.0 0.5 1.0 1.5 2.0 Floor deflections at 9 points Time (s) 0 100 200 300 400 500 De flection (mm) -700 -600 -500 -400 -300 -200 -100 0

Measurements on test assembly

to determine time to floor failure

• Temperatures

• Flame penetration

• Deflections

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Structural Response of the Test Assemblies

Deflection prior to floor failure

a) Tests with open basement doorway Time (s) 0 100 200 300 400 500 600 700 Def lect ion ( mm) -350 -300 -250 -200 -150 -100 -50 0 UF-01 UF-03 UF-04 UF-05 UF-06 UF-06R UF-06RR UF-07

b) Tests with closed basement doorway Time (s) 0 100 200 300 400 500 600 700 Def lect ion (mm) -350 -300 -250 -200 -150 -100 -50 0 UF-02 UF-08 UF-09

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Primary Mode of Floor Failure

Solid wood joist assemblies

• subfloor failure (burn through)

• most of the joists charred but still in place

Engineered floor assemblies

• joist or truss failure

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Primary Mode of Floor Failure

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Primary Mode of Floor Failure

Wood I joists A and B: web materials burned through

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Primary Mode of Floor Failure

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Primary Mode of Floor Failure

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Time (s)

0 200 400 600 800 1000 1200 1400

onset of untenable conditions

initiation of fire 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400

floor not usable for egress

Solid wood joist

Wood I-joist A

Steel C-joist

Wood I-joist B

open

basement

doorway

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initiation of fire

0 200 400 600 800 1000 1200 1400

Open 0 200 400 600 800 1000 1200 1400 Closed 0 200 400 600 800 1000 1200 1400 Open 0 200 400 600 800 1000 1200 1400 Closed (s) 0 200 400 600 800 1000 1200 1400 Open 0 200 400 600 800 1000 1200 1400 Closed

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0 200 400 600 800 1000 1200 1400

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0 200 400 600 800 1000 1200 1400

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Key Findings

Tests with an open stairwell to the basement

• Fire events followed a chronological sequence:

– initiation of the fire

– activation of smoke alarms

– loss of tenable conditions in open areas on upper storeys

– finally structural failure of the test floor assembly

• Untenable conditions for occupants in open areas on upper storeys were reached at approximately the same time regardless of the type of the test floor assemblies • The untenable conditions were reached before failure of

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Key Findings (continued)

Limited tests with a closed door to the basement

3 assemblies: solid wood joist, wood I-joist, metal-web wood truss

• Reduced the rate of fire growth in the basement

• Slowed the transport of combustion products from the basement to the upper storeys

• Delayed the time to reach tenability limits for occupants on upper storeys

• Delayed the times for the test floor assemblies to reach structural failure

• Metal-web wood truss assembly failed before tenability limits were reached in open areas on upper storeys

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Key Findings (continued)

All tests

• The time to reach failure for the engineered assemblies was shorter than for the solid wood joist assemblies

• Untenable conditions were not reached, for the duration of the tests, in the second-storey bedroom where the door to the bedroom was kept closed

• Results support the code requirement for working

interconnected smoke alarms on each level of a house to alert occupants as early as possible in the event of a fire • Results reinforce the importance of continued public

education on home fire safety, fire emergency

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Fire Performance of Houses Phase 1

Study of Unprotected Floor Assemblies in Basement Fire Scenarios Summary http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rr/rr252/rr252.pdf Part 1 http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rr/rr246/rr246.pdf Part 2 http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rr/rr247/rr247.pdf Part 3 http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rr/rr248/rr248.pdf Part 4 http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rr/rr249/rr249.pdf Part 5 http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rr/rr250/rr250.pdf Part 6 http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/rr/rr251/rr251.pdf

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Further Studies

Consortium project (2008-2010) – protected floor assemblies in basement fire scenarios

• engineered floor systems protected by gypsum board, sprinkler or suspended ceiling

• Impact of the protection measures on fire performance and tenability conditions

Fire Performance of Houses Phase 2 (starting 2011) • Wall systems for single-family houses

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Acknowledgments

Project partners (Phase 1):

• Canada Mortgage and Housing Corporation

• Canadian Automatic Sprinkler Association

• Canadian Wood Council

• Cement Association of Canada

• City of Calgary

• FPInnovations - Forintek Division

• North American Insulation Manufacturers Association

• Ontario Ministry of Community Safety and Correctional Services/Office of the Fire Marshal

• Ontario Ministry of Municipal Affairs and Housing

(45)

Acknowledgments

NRC-IRC project team:

• J.Z. Su • N. Bénichou • A.C. Bwalya • G.D. Lougheed • B.C. Taber • P. Leroux • G. Proulx • A. Kashef • C. McCartney • J.R. Thomas

(46)

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Fire performance of houses - Phase 1 study of basement fires with unprotected floor assemblies

Fire Performance of Houses

Phase-1 Study of Basement Fires with

Unprotected Floor Assemblies

Fire Performance of Houses – Outline



Background



Objectives



Experimental Program



Advent of new materials and innovative

products/systems used in construction of houses



Need to better understand performance and

impact on the life safety of occupants under fire

conditions



CCBFC and CCCME requested NRC to

undertake research

Objectives

To better understand

Experimental Program

Test Facility



A full-scale test house simulating a two-storey

detached single-family house with a basement

Basement

Basement Ceiling – Unprotected Assemblies

First Storey

First Storey

Loading on Test Floor Assembly

Fire Scenarios

Measurements and Analysis

Tenability Analysis

Tenability Analysis – gas measurements

Tenability Analysis – temperature measurements

Tenability Analysis – optical density measurements

Tenability Analysis – estimation of time to

untenable conditions

open

basement

doorway

open

basement

doorway

Structural Response of Test Assemblies

Structural Response of the Test Assemblies



Deflection prior to floor failure

Primary Mode of Floor Failure



Solid wood joist assemblies

•

subfloor failure (burn through)

•

most of the joists charred but still in place



Engineered floor assemblies

•

joist or truss failure

Primary Mode of Floor Failure

Primary Mode of Floor Failure

Primary Mode of Floor Failure

Primary Mode of Floor Failure

open

basement

doorway

Key Findings



Tests with an open stairwell to the basement

Key Findings (continued)



Limited tests with a closed door to the basement

Key Findings (continued)



All tests

Further Studies

Acknowledgments