1

CE 808: Structural Fire

Engineering

V. Kodur

Professor

Dept of Civil and Env. Engineering

Michigan State University

Ch. 1: INTRODUCTION TO FIRE SAFETY

CE 808 Chap 1 1-2

Ch. 1: Introduction To Fire Safety

Fire Problem

Importance of Fire Safety

Structural Fire Safety within the Context of Overall

Fire Safety

Fire Resistance

Codes and Standards

Performance-based Design

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CE 808 Chap 1 1-3

Background

Building fires cause thousands of deaths and billions of

dollars of damage each year

Fire risk can be mitigated through conscientious design

and maintenance

It is impossible to prevent ALL major building fires

Fire safety depends on numerous factors:

Fire prevention, suppression and extinction Successful evacuation of occupants Structural integrity (FOCUS of this course)

Engineers must ensure fire safety through proper

selection and design of material & structural systems

1-4

Fire Problem

Fire Costs in US (Canada)

Recent data: 2013 (2002)

Fire incidents: 1.24 million (42753) Fire deaths: 3240 - 97 FF (224 - 2) Fire injuries: ~15,925 61 FF (1067) Direct property losses: - $11.5 b ($1.55 b) Total cost of fire: > $328b (~$7b??)

Losses caused by fire + cost of fire protection, detection and mitigation Residential fires are the most significant 83% of fire deaths, 27% of fires, 60% of the total $loss

Residential fires are the most significant

83% of fire deaths, 27% of fires, 60% of the total $ losses (US) Smoker's material and open flame are the number one

source of ignition (~ 25% of the total)

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CE 808 Chap 1 1-5

Fire: Age old Problem -

The Great Fire of London

2nd September 1666, London, UK

Within 5 days the city was destroyed by fire

440 acres consumed, 87 churches, 13 200 homes

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Recent Fire Incidents - USA WTC Disaster Sept. 11, 2001

Fires - crucial to collapse

2850 deaths ( > 450 ER)

Damage ( $10s B) Collapsed/damaged buildings - 40

Towers standing today! (if no fires)

The Rhode Island nightclub fire Feb. 20, 2003

caused by pyrotechnics set off which ignited flammable sound insulation foam in the walls and ceilings surrounding the stage

100 deaths

200+ injured

$175 million offered to victims families Oakland Bridge - April 29, 2007 Gasoline tanker crashed into the bridge Collapse by fire (22 mins) Traffic disruption

CA Tunnel October 12, 2007

550 ft long tunnel Burned for 7 hrs 1400C Severe damage Spalling of concrete

Oakland Bridge Collapse

Euro Tunnel

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CE 808 Chap 1 1-7

Recent Fire Incidents WTC Buildings Structural Fire Safety

45,000 liters in each plane 25% Fire balls

25% Shafts

50% Consumed in few minutes

Fire size 3-5 GW Energy nuclear plant

Fire temperatures 1100 C

Fires were instrumental Towers would have been standing

Structural Fire Safety

CE 808 Chap 1 1-8

Magnitude of Fire Problem

Comparison of probability of fire incidents and fire-induced

collapse in bridges and buildings i,ii

Bridges Buildings 2000 2012*, 2002**

Total number of structures 691,060 118,000,000

Reported fire incidents 4500 480,500

Probability of a fire breaking out (yearly) 2.27% 29.5%*

Number of collapsed structures 503 225

Number of collapsed structures due to

fire 16

29

Probability of collapse due to fire (yearly) 3.1% 12.1%**

i Naser M.Z., Kodur V.K.R. (2015). A Probabilistic Assessment for Classification of Bridges Against Fire Hazard. Fire Safety Journal, Vol. 76, pp. 6573. ii Kodur V.K.R., Naser M.Z. (2013). Importance Factor for Design of Bridges Against Fire. Engineering Structures, Elsevier, Vol. 54, pp. 207-220.

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CE 808 Chap 1 1-9

Oakland Bridge - April 29, 2007

Gasoline tanker crashed into a

pylon on the interchange

between I-80 and I-880

8600 gallons of gasoline burnt

to a temperature 1100C.

Continuous fire softened the

bolted connections

The result is clean breaks at

the connections

Severe structural damage

Severe traffic delay

Losses Millions of dollars

Clean breaks at the connection due to fire exposure Oakland Bridge Collapse

Recent Fire Incidents Infrastructure

CE 808 Chap 1 1-10

Tunnel in California - Oct 12, 2007

Two trucks collided 30 trucks & passenger cars Burned 7 hrs 1400C Severe damage

Deaths (3) & Injuries (10)

Thermal spalling

Spalling depth (concrete

cover)

HSC Permeability - low

Major repairs damages

Fire-Induced Spalling of Concrete Tunnel in California

Recent Fire Incidents Infrastructure

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Recent Fire Incidents - Europe

Apr. 13, 2009: Hostel fire, Kamie Pomorski, Poland, 21 died

DELFT Faculty of Architecture Bldg - May 13, 2008

13 storey RC building, collapsed - 7 hrs

Aug. 18, 2007: Newquay, UK, Penhallow Hotel Fire, 3 deaths. Hotel collapsed.

Apr. 15. 2005: Paris Opera Hotel , France, 24 deaths

Feb. 12, 2005: Windsor Tower Fire, Madrid, Spain. Partial collapse - Demolished

Nov. 24, 2003: Fire in Student Hostel due to Electrical Fault, Moscow, Russia. 36 deaths.

May 15, 2003: Hotel in La Plaine district, Marseilles, France, 10 deaths

April 18, 2002: A plane crashed into the upper floors of the 30-story Pirelli Tower in Milan, Italy, 3 deaths.

December 2001: Home for elderly people, Buccino, South Italy, 21 deaths.

Nov. 18, 96 - Euro Tunnel Fire

Severe damage, concrete spalling - Major repairs (50 M)

Fire in Technical University of Delft,

Architecture Building

CE 808 Chap 1 1-12

Euro Tunnel Fire - Nov 96

Burned 8 h 1000C Severe damage

Injuries (8), services (50M)

Thermal spalling RC tunnel rings (100's m) Av. depth 10-20 cm

Strength - 80~100 MPa Permeability - low

Major repairs damages

2007 Another fire in Tunnel

Fire-Induced Spalling of HSC Tunnel

Lining & Buckling of reinforcement in Channel

Tunnel due to Fire on Nov 18, 1996

Recent Fire Incidents Material Problems

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Recent Fire Incidents in China Nov. 15, 2010: Res Building, Shanghai, 54 deaths.

Nov. 5, 2010: Jinlin Mall, Jilin, 19 deaths.

Aug. 10, 2009: Jiahe Tower, Hong Kong, 4 deaths.

Feb. 9, 2009: CCTV Tower Fire, Beijing, 1 death,

163.8 million RMB losses.

Sep. 14, 2006: Fuyin Mall, Huzhou, Zhejiang, 15

deaths.

Dec. 15, 2005: Liaoyuan Hospital Fire, Jilin, 40

deaths.

Jun. 10, 2005: Huanan Hotel, Shantou, Guangdong,

31 deaths.

Feb. 15, 2004, Zhongbai Mall, Jilin, 53 deaths.

Nov. 3, 2003: Hengyang Tower, Hunan, building

collapse, 20 FF deaths.

Jun. 5, 2001: Nanchang central Kindergarten, Jiangxi,

13 children deaths.

CE 808 Chap 1 1-14

Fire Safety

Fire - severe conditions Buildings, transit systems Fire safety major design requirement

loss of life and property

Fire resistance - structural elements Safe evacuation of occupants & fire personnel Minimize property damage Control spread of fire

Recent events WTC, Tunnels

Structural Fire Safety - Fire resistance

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CE 808 Chap 1 1-15

Fire Safety Type of Structures

Buildings - commercial, industrial, residential

Outdoor stadium

Oil platform

Tent

Stage

Tower

Liquid storage tanks etc.

CE 808 Chap 1 1-16

Role of Structures

Provide comfortable, safe, functional space

Shelter and Support Resist forces - human and natural:

Dead Live Wind (hurricane & tornado) Flood Snow Earthquake Thermal Fire

Primary or Secondary Event

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CE 808 Chap 1 1-17

Fire Safety

Not possible to prevent ALL fires

So, designers need to put in-place strategies to minimize the occurrence of fires & consequently reducing their impact on life, property and environment

Main strategies include providing for: Automatic fire sprinklers - statistics show that sprinklers have

a very high probability of controlling or extinguishing any fire

Systems for fire detection and notification of fire service Safe travel paths for the movement of occupants & firefighters Barriers to control the spread of fire & smoke Fire resistant structures - no to collapse prematurely in fire

To strategize, the designer has the important responsibility to

properly select, design and use building materials

CE 808 Chap 1 1-18

What is Fire Resistance?

Fire resistance: the property of a material or

assemblage to withstand fire or give protection

from it.

Discussion: As applied to elements of buildings, it is

characterized by the ability to confine a fire or to

continue to perform a given structural function, or

both. [ASTM E176, 1997]

Note the absence of specification of exposure or time

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CE 808 Chap 1 1-19

Fire Resistant Assemblies

Provide physical barrier to restrict fire

spread

prevent fire and smoke spread

Maintain structural integrity/ load

carrying ability despite exposure

prevent structural collapse

Compartmentation & Structural integrity are principal aspects of fire safety in

buildings

Fire Resistance Rating - Codes

CE 808 Chap 1 1-20

Fire Resistance

Fire resistance is usually described as passive

fire protection, always ready and waiting for a fire

does not play a significant role in the early stages of a fire becomes very important as a fire grows beyond flashover

The importance of fire resistance depends on the

size of the building & the fire safety objectives

that need to be satisfied

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CE 808 Chap 1 1-21

Fire Resistance & Fire Safety Goals

Life safety

Occurrence of civilian fatalities in fire resistive

buildings: MGM, Winecoff and DuPont Plaza Hotels

Occurrence of fire fighter fatalities in collapses

Mission continuity

Appreciable down time if collapse occurs: GM Livonia

Plant, McCormick Place

Outcome of 1st Interstate, Broadgate, Meridian

Plaza, WTC

CE 808 Chap 1 1-22

Codes and Standards

Building codes set fire-resistance requirements for building assemblies to resist

Spread of fire within buildings & Collapse of structural elements exposed to fire

Fire Resistance Rating

The Subcommittee (ASTM) believes that the idea of designing some buildings for the full fire severity corresponding to the occupancy is a logical advance in fire protection engineering. (BMS 92, 1942)

Formulated based on Ingbergs hypothesized relationship betn occupancy (fuel load) building area (compartmentation level)

Determine maximum allowable height & area of a building based on:

Construction type Occupancy

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CE 808 Chap 1 1-23

Codes - Fire Resistance Rating

Fire resistance rating (or fire endurance): a measure of the elapsed time during which an assembly

continues to exhibit fire resistance under specified

conditions of test and performance [Boring, Spence and Wells, 1981].

Fire Resistance Rating 30 min, 45 min, 1, 11/2, 2, 3, 4h

which test?

ASTM E119, NFPA 251, UL 263, ULC S101, ISO

834

CE 808 Chap 1 1-24

Codes - Occupancy Types

Assembly

Business

Educational

Factory &

Industrial

High Hazard

Institutional

Mercantile

Residential

Storage

Utility/Miscellaneous

Specifies fire resistance requirements based on occupancy type

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CE 808 Chap 1 1-25

Codes - Types of Construction

Type I - Non-combustible, fire resistant

Concrete, Masonry, Structural Steel

Type II - Non-combustible, minimally or non-fire resistant

Lt gauge steel framing

Type III - Non-combustible exterior walls, combustible interior elements

Wood stud walls

Type IV - Heavy timber

Structural members

Type V - Wood frame

Wood stud walls/wood joist floors

CE 808 Chap 1 1-26

Codes - Types of Construction

3 Digit Code, e.g. 332 --- 3h,3h,2h

1st digit: fire resistance of exterior bearing wall 2nd digit: fire resistance of columns, beams, girders,

trusses and arches supporting bearing walls, columns

or loads from more than one floor

3rd digit: fire resistance of floor construction H Heavy timber

UL Unlimited height/area

NFPA 220, Standard on Types of Building Construction

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CE 808 Chap 1 1-27

Codes - Height and Area Table (NFPA 5000)

Type I Type II Type III Type

IV Type V

Occupancy

/Group 442 332 222 111 000 211 200 2HH 111 000

(Ht./Area)

Business

UL

UL

UL

UL

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UL

5

37.5

4

23.0

5

28.5

4

19.0

5

36.0

3

18.0

2

9.0

Education UL

UL

UL

UL

5

UL

3

26.5

2

14.5

3

23.5

2

14.5

3

25.5

1

18.5

1

9.5

Mercantile

UL

UL

UL

UL

11

UL

4

21.5

4

12.5

4

18.5

4

12.5

4

20.5

3

14.0

1

9.0

UL: Unlimited Height in Storeys Area in sq. mtrs

CE 808 Chap 1 1-28

Codes - Construction Type Requirements

Group

Type I Type II Type III Type IV Type V

442 332 222 111 000 211 200 2HH 111 000

Structural

Frame 4/3 3/2 2/1 1 0 1 0 H 1 0

Bldg Walls

Exterior

Interior

4

4/3

3

3/2

2/1

2/1

1

1

0

0

2

1

2

0

2

2/1

1

1

0

0

Floor 2 2 2 1 0 1 0 H 1 0

Roof 2 1 1 1 0 1 0 H 1 0

NFPA 5000

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CE 808 Chap 1 1-29

Fire Resistance Analysis

Typical: Prescriptive Approach Refer to results from standard test; no

engineering analysis required (structural design given)

ASTM E119, NFPA 251, UL 263, ISO 834

Conduct new test Special cases:

special buildings, problems with architectural features, cost

Future: performance-based design, integrated into

the structural and fire protection engineering design

Primary responsibility: FPE, CE, or ?

Preserves structural design

Meets architectural requirements

CE 808 Chap 1 1-30

Prescriptive Approach

Till recently codes have been prescriptive in

nature for fire resistance evaluation

Prescriptive codes

state how a building is to be constructed restrict designers to take a rational engineering

approach to the provisions of fire safety

Traditional method for assessing the fire resistance of building assemblies is by means of standard fire tests

Recently, there has been an increase in the use of

calculation/engineering methods

Performance-based design

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CE 808 Chap 1 1-31

Many countries are moving towards performance-based codes which

Sate how a building is to perform under a wide range of conditions Allow designers to use alternate fire safety strategies, provided

adequate safety can be demonstrated

Use of calculation/engineering methods

Within a prescriptive code, there may be possibility to allow for performance-based selection of structural assemblies

if a code specifies a floor with a fire resistance rating, designers have the flexibility to select from a range of listed systems which have sufficient fire resistance

This course, will examine provisions for assessing fire performance of systems where no tests or listings are available

Performance-based Building Codes

CE 808 Chap 1 1-32

Performance-based Building Codes

In developing new codes, many countries have adopted

a multi-level code format in the form of:

overall goals, functional objectives and required performance which must be achieved

selection of alternative means of achieving those goals. The three most common options are:

to comply with a prescriptive 'Acceptable Solution', to comply with an approved standard calculation method, or to perform a performance-based fire engineering design from

first principles

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CE 808 Chap 1 1-33

Standard calculation methods have not yet been developed for widespread use

So, compliance with performance-based codes is usually achieved by: Mainly satisfying the requirements of acceptable solutions, or Carrying out a performance-based alternative design based on

fire engineering principles

Alternative designs can be used to justify cost-effective solutions

Under a performance-based design, it is essential to have comprehensive documentation & quality control The calculations should be included in a report which describes

the building & the complete fire design process

Performance-based Building Codes

CE 808 Chap 1 1-34

Emerging Trends - New Materials

HPM - HSC, FRP, HPS

Benefits Superior performance

Strength, Durability

Corrosion resistance

Applications Bridges, Infrastructure projects

Retrofitting & strengthening

HPM Plastics, Composites Benefits

Superior strength, Lt.wt

Applications Auto, Aerospace, Transportation

Major Problem Fire Performance High temperature intolerant Toxicity Flame spread (combustible) Faster strength/stiffness degradation Ex: Euro-tunnel fire Ex: Challenger, Colombia crash

FRP Rebar

Column Strengthened

with FRP

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CE 808 Chap 1 1-35

Current approach to fire safety design

Prescriptive based approach Significant drawbacks

US/Canada is moving towards performance-

based codes

Rational engineering approaches Offers cost-effective, innovative & alternate designs

Factors hindering PB Approach

Lack of validated models Lack of test data for validation Lack of material properties Lack of design tools/guidelines Lack of trained personnel Lack of monitoring tools

Emerging Trends PB Codes