9. FIRE

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9. FIRE
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Introduction

• Many fires are associated with the use of
  high-risk materials and, through ongoing
  legislation should result in continuing
  improvements
• it often takes several years before older,
  high-risk materials are replaced.
• In large or tall buildings, the much higher
  potential risk resulting from reduced access of
  emergency services has long been recognized
  through again, fires still occur, sometimes due
  to failure of one or two parts of the structure
  to prevent fire spread.
• Increasing attention is now being given to fire
  stops in cavities, ducts and roof spaces.

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Combustion

• Three prequisites for a fire are
• Fuel
• Oxygen
• Heat
• 1. Fuel
• Almost all organic materials behave as fuels.
• Carbon and Hydrogen are the main constituents so
  that the materials rich in these will be a
  greater hazard and especially those rich in
  hydrogen, such as oil products and gas, since
  hydrogen generates more heat than carbon.

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• 2. Oxygen
• This is present in the form of air, diluted with
  nitrogen which is inert.
• Pure oxygen, sometimes stored in cylinders is
  highly dangerous.
• 3. Heat
• Heat causes
• Chemical decomposition of most organic materials
  releasing volatile vapor. This effect is called
  PYROLYSIS.
• Reaction between both the solid and vapour
  fraction and oxygen
• C O2 ? CO2 heat (solid fuel)
• CH4 2 O2 ? CO 2H2O Heat (hydrocarbon fuel)
• These are combustion processes though it is the
  reaction of vapor with oxygen together with
  accompanying light emission that is described as
  a FLAME

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Flame

• They are not necessary for fire but their
  pressure usually increases the severity of a
  fire.
• Because
• Gases have much greater mobility than solids so
  that flames help spread the fire.
• The temperature in a flame is very high- usually
  ? 1200oC.

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Ignition

• The application of sufficient heat will initiate
  the combustion process, which then generates more
  heat and ultimately, when the temperature is high
  enough, ignition or flaming will occur.

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Fire and Density

• The ideal for habitable buildings might be
  considered to be avoidance of all combustible
  materials.
• Normally totally impracticable
• because organic materials are inseparably linked
  to human comfort furniture, furnishings,
  clothing- and to human activity-books paper and
  implements.
• In many cases for reasons of economy and/ or
  convenience the enclosure itself will involve
  combustible materials (wooden floors, doors,
  window frames and partitions).

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Fire Load

• The risk presented by the combustible contents of
  an enclosure is defined as FIRE LOAD.
• Fire Load total mass of combustible contents
  in the enclosure
• expressed as wood equivalent per unit floor area.
• Fire Load Comb.mass/(m2 (floor))
• Higher fire loads produce longer duration fires.

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• Fire Severity
• Depends on
• Type and decomposition of combustible material,
• Ventilation characteristics
• good ventilation may reduce the durability of
  fires by venting heat.

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Development of Fires

• Damage of fire depends on
• situation which give rise to it,
• the way in which it develops and spreads.
• In the early stages of most fires, spreading is
  largely the result of flaming and localized heat
  generation,
• hence it requires materials which are not only
  combustible but in a flammable form.

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Flashover

• It is the most important stage in any fire (See
  Figure 9.1).
• Occurs when the air temperature in the enclosure
  reaches about 6000C.
• At that point, pyrolysis (vaporisation) of all
  combustable materials takes place so that they
  all become involved in the fire and flaming
  reaches dramatic proportions, limited only by the
  total fuel available and/or by the supply of air.

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Figure 9.1 BS476 tests relating to initiation,
growth, and spread of an uncontrolled fire in the
compartment of origin.
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• In many such fires, flaming occurs mainly outside
  windows using to lack of air internally and this
  helps spread the fire upwards to adjacent floors
  of the building.
• A priority in design for fire resistance is to
  prevent or delay flashover since there is little
  change of survival in an enclosure once this has
  occurred.

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• The thermal inertia of the surfaces of an
  enclosure is an important factor
• highly conductive, heat absorbent materials such
  as brick, help to delay the temperature rise as
  well as being non-combustible.
• Flashover may be prevented in poorly ventilated
  closures due to lack of air for combustion, or
  delayed in very large ones where there are large
  volumes of air in relation to available fuel-they
  have a cooling effect.
• It is estimated at present that the fire services
  arrive before flash-over in about 90 of fires.

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Fire Tests

• Fire tests attempt to classify materials and
  components in relation to fire performance and
  form the basis of Building Regulations. They
  cover 2 chief areas
• 1. The development and spread of fire.
• These tests include combustability, ignitibility,
  fire propogation, spread of flame and heat
  emission of combustible materials.
• 2. Effects of fire on the structure, adjacent
  structures and means of escape, the first
  priority in any fire being the safety of the
  occupants.
• These tests are concerned with the structural
  performance of buildings, their ability to
  contain the fire and problems associated with
  smoke.

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• Many of the above aspects are covered by BS476,
  Figure 9.2. A brief resume of the contents of
  parts relating to fire spread in current Building
  Regulations is given in Table 9.1.
• Examples on fires
• Collapse of World Trade Centers (New York)

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Figure 9.2 Five ways in which fire can be
initiated.
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Table 9.1 BS476 tests relating to fire
development and spread referred to in current
Building regulations.
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BURNING OF CONCRETE
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After Fire

• the amount of debris,
• blackening of the structure,
• Peeling,
• loss of finishes,
• can give the impression that the concrete
  elements are severely damaged.

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Assessing fire-damage

• An inspection of the site including limited
  non-destructive testing, sampling and laboratory
  investigation to produce a repair classification
  for each element.
• Experienced practitioner can obtain a significant
  amount of information during a site inspection.
• Laboratory investigation is often critical to
  establish the temperature achieved at different
  depths in the concrete and thus the condition of
  that element.
• An indispensable technique is the investigation
  in petrographic examination.

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General considerations

• Loss of strength and modulus of elasticity
• Concrete looses strength on heating.
• Residual strength of a concrete element after a
  fire depends on several factors, for temperatures
  up to 3000C the residual strength of
  structural-quality concrete is not severely
  reduced.
• Concrete is unlikely to possess any useful
  structural strength if it has been subjected to
  temperatures above 5000C, the strength then being
  reduced by about 80.

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• Typically, concrete made with lightweight
  aggregate does not lose significant strength
  until 500oC.
• The effects of a fire on modulus of elasticity
  are similar to the effects on strength.
• Up to 300oC, the modulus of elasticity is not
  severely reduced but by 800oC it may be as little
  as 15 of its original value (85 loss).

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Effects of fire on reinforcement

• Steel looses strength on heating but
  reinforcement is often protected from the effects
  of fire by the surrounding concrete, which is a
  poor thermal conductor.
• Steel reinforcement suffers a reduction in yield
  strength at temperatures above 450oC for
  cold-worked steel and 600oC for hot-worked steel.
  
• Prestressed steel looses tensile strength at
  temperatures as low as 200oC and by 400oC may be
  at 50 of normal strength.
• Buckling of reinforcement can occur at high
  temperatures if there is restraint, for example
  by adjacent elements, against thermal expansion.

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Spalling of concrete after fire

• In a fire, most concrete structures spall to some
  extend, although lightweight aggregate concretes
  are usually more resistant.
• The surface can scale in the early stages of a
  fire as the near-surface aggregate splits as a
  result of physical or chemical changes at high
  temperatures.
• Explosive spalling also occurs in the early
  stages of a fire but involves larger pieces of
  concrete violently breaking away from the surface
  and may continue from areas already spalled. Such
  spalling usually results from high moisture
  content in the concrete.
• The thermal shock of a cold water on to hot
  concrete during fire-fighting can also induce
  spalling.

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Depth of damage

• Concrete is a poor thermal conductor and so high
  temperatures will initially be confined to the
  surface layer with the interior concrete
  remaining cooler.
• At corners where two surfaces are exposed to the
  fire, the effect will penetrate further because
  of the transmission of heat from the two
  surfaces.
• If concrete spalls early in a fire, the depth of
  effect from the original surface will be greater
  than if the concrete does not spall or if
  spalling occurs later in the fire.

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Damage assessmentSite inspection

• Various features of the concrete and associated
  materials in the fire-affected locations must be
  noted and from these a visual classification of
  the damage produced.
• The Concrete Society report (CSTR 33) includes a
  useful numerical classification and this is shown
  in a simplified format in Table 9.2

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Table 9.2. CSTR 33 classification of fire damage.
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Damage assessmentSite inspection

• Firstly, the condition of any plaster or other
  surface finishes is noted.
• Surfaces may be sooty but otherwise unaffected by
  the fire.
• As the effects become more severe, the finishes
  start to peel until they are completely lost or
  destroyed.
• Likewise, during the fire the concrete surface
  will progressively craze until it is lost.
• The concrete color may also be affected during
  the fire, generally changing with increasing
  temperature from normal through pink to red, then
  whitish grey and finally buff.

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• The pink and red colours relate to the presence
  of small amounts of iron in some aggregates,
  which oxidise and can be indicative of particular
  temperatures.
• It is important to note that many concreting
  aggregates do not change colour at temperatures
  normally encountered in an ordinary fire.
• Although colour change clearly indicates a
  particular temperature, the absence of colour
  change does not mean that the temperature was not
  reached.

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Other site investigation requirements

• Cores - or, if these are not possible, lump
  samples - should be taken for laboratory
  investigation from a number of locations
  representing the range of damage classifications
  observed and should include comparable unaffected
  concrete as a control.
• Laboratory petrographic examination is necessary
  to support and enhance the site findings.

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• The depth of cover to any reinforcement must be
  measured during site investigation so that, once
  the laboratory investigation has been completed,
  it will be possible to determine whether the
  steel is likely to have been affected by the
  fire.
• It is also possible to take steel samples for
  laboratory analysis, but this is usually
  necessary only if the visual inspection reveals a
  cause for concern.

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Laboratory investigation petrographic examination

• Petrographic examination should be conducted by
  someone experienced in the technique and in
  examining fire-damaged concrete, and is best
  performed in accordance with ASTM C856.
• An initial low- to medium-power microscopic
  examination of all cores allows the selection of
  those for thin-section preparation and more
  detailed examination with a high- power
  microscope.

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• As well as identifying physical distress such as
  cracking, this examination can identify features
  that allow temperature contours' to be plotted
  on the concrete.
• Binocular examination allows contours to be
  plotted that equate to around 300C provided the
  aggregate has become pink, the colour deepening
  to brick-red between 500C and 600C.

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• Any flint in the concrete calcines (loses its
  water component, about 4 ) between 250C-450C,
  while at similar temperatures the normally
  featureless cement paste begins to show patchy
  anisotropy with yellow-beige colours.
• Thus, careful and informed petrographic
  examination can usually reveal an
  approximate 500C contour.
• Cracking of the surface of the concrete occurs at
  relatively low temperatures, but deep cracking
  indicates around 550C was reached.

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• Quartz alters structurally at 575C resulting in
  a volume increase that typically causes extensive
  fine microcracking.
• As most concrete contains quartz, an approximate
  600C contour can usually be plotted.
• The change in colour from brick-red to grey also
  begins at 600oC.
• Limestone aggregate calcines at 800C and
  concrete becomes a buff colour by 900C.

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Laboratory investigation

• Another laboratory technique sometimes used to
  assess the temperature reached is
  thermo-luminescence.
• Based on the fact that quartz emits visible light
  when heated to 300-500C, unless it has already
  been heated to that temperature.
• It is be possible to establish the depth to which
  the concrete has been affected.
• The usefulness of this method is somewhat reduced
  by its limited availability and cost.
• However in special circumstances,
  thermo-luminescence is invaluable, despite the
  expense.

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Overall assessment

• The visual damage classification prepared on site
  provides the basis for a repair strategy.
• However the laboratory investigation -
  particularly the petrographic temperature
  contouring - provides critical information about
  the depth of any fire damage, and any
  classification of damage should be reviewed after
  the laboratory investigation.
• Critical temperatures (T) are as follows
• T gt300oC considerable loss in strength of the
  concrete.
• T 200-400C considerable loss of strength of
  prestressed steel.
• T gt450oC loss of residual strength of
  cold-worked steel.
• T gt600C loss of residual strength of hot-rolled
  steel.

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Options for repair requirements for demolition

• Detailed information about repair is given in
  CSTR 33.
• A brief guide to the level of repair required can
  be based on the final classification of damage.
• On the basis of practical experience, Figure 9.3
  has been devised to illustrate the types of
  repair that might be appropriate for different
  classes of damage.

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World Trade Centre - New York - Some Engineering
Aspects

• General Information
• Height 417 meters and 415 meters
• Owners Port Authority of New York and New
  Jersey.(99 year leased signed in April 2001 to
  groups including Westfield America and
  Silverstein Properties)
• Architect Minoru Yamasaki, Emery Roth and Sons
  consulting
• Engineer John Skilling and Leslie Robertson of
  Worthington, Skilling, Helle and Jackson
• Ground Breaking August 5, 1966
• Opened 1970-73 April 4, 1973 ribbon cutting
• Destroyed  Terrorist attack, September 11, 2001

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Figure 9.3. Simplified illustration of
Classification and Repair.
Some peeling of finishes, slight crazing minor
spalling. Class 1 rapair slight damage.
Total loss of finish, Whitish grey
colour, Extensive crazing, Considerable spalling
up to 50 reinforcement exposed, minor cracking,
class 3 principal repair involving strengthening.
Much loss of finish, pink colour, crazing, up to
25 reinforcement exposed, class 2 restoring
cover to reinforcement with general repairs
reinforced with light fabric
Plaster paint intact, Class 0 clean
redecorate if required.
Finishes destroyed, buff colour, surface lost,
almost all surface spalled, over 50
reinforcement exposed, major cracking. Class 4
major repair involving strengthening or
demolition replacement.
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• EXAMPLE from Cyprus

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TRNC Ministry of Culture Education, Turkish
Cypriot State Theatre Hall
Theatre Hall- after fire, 2006
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State Theatre Hall /Lefkosa-After fire in 1999
duration 20 minutes only
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State Theatre Hall /Lefkosa-After fire in 1999
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State Theatre Hall /Lefkosa-After fire in 1999
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State Theatre Hall /Lefkosa-After fire in 1999
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State Theatre Hall /Lefkosa-After fire in 1999
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State Theatre Hall /Lefkosa-After fire in 1999
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State Theatre Hall /Lefkosa-After fire in 1999
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Theatre Hall after fire, 2006
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Theatre Hall after fire, 2006
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• More examples

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Caracas Fire
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Taiwan
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Interstate bank
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Madrid
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Madrid
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Meridian Plaza
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The Windsor Building Fire, Madrid, SpainHuge
Fire in Steel-Reinforced Concrete Building Causes
Partial Collapse
Time Collapse Situation 129 East face of the
21st floor collapsed 137 South middle section of
several floors above the 21st floor gradually
collapsed 150 Parts of floor slab with curtain
walls collapsed 202 Parts of floor slab with
curtain walls collapsed 211 Parts of floor slab
with curtain walls collapsed 213 Floors above
about 25th floor collapsed Large collapse of
middle section at about 20th floor 217 Parts of
floor slab with curtain walls collapsed 247 South
west corner of 1 2 floors below about 20th
floor collapsed 251 Southeast corner of about
18th 20th floors collapsed 335 South middle
section of about 17th 20th floors collapsed
Fire broke through the Upper Technical
Floor 348 Fire flame spurted out below the Upper
Technical Floor 417 Debris on the Upper
Technical Floor fell down
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Sunday, Jan. 10, 2016 photo, the burned hulk of
The Address Downtown is seen in Dubai, United
Arab Emirates. Skyscraper fires like the blaze
that struck the 63-story luxury hotel in Dubai on
New Year?s Eve, 2016, swiftly turning it into a
towering inferno, are not that rare. The fire in
Dubai has raised new issues about the safety of
exterior sidings put on high-rise buildings in
the United Arab Emirates and around the world.
(AP Photo/Jon Gambrell)
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Assessment of fire damaged structuresBRE
Information Paper IP 24/81

• Buildings, or portions of buildings, look a
  sorry sight after a fire
• some may have collapsed and be only twisted
  ruins, others may have mainly suffered damage
  from smoke.
• Between these extremes there is a wide range of
  degree of damage.
• Where there is no visible damage such as
  charring of timber, spalling of concrete or
  distortion of steelwork, there is generally
  little likelihood of permanent loss of
  strength of the material although this cannot
  always be assumed.
• It is essential to do a thorough inspection of
  the complete premises in order to ensure that
  damage,
• eg through thermal expansion or water leakage,
  has not occurred in those parts not directly
  involved in the fire.

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TEMPERATURES REACHED IN FIRES AND ESTIMATION OF
FIRE SEVERITY

• Standard fire resistance tests determine the
  period of time for which elements of building
  construction should fulfill their design function
  of load bearing and / or fire separation while
  exposed to heat in accordance with a
  predetermined time / temperature relationship is
  an idealisation of an uncontrolled growing fire
  in a room.
• It assumes an unlimited supply of fuel and its
  burning rate, being controlled mainly by
  ventilation condition, follows a predictable
  pattern.

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• In real incidents, fire may have remained
  localised for a long time, the rate of
  temperature rise may have been faster, or slower,
  than in the standard test, or extensive spread
  may occur.
• Different rooms and different parts of a building
  may have suffered different fire intensities.
• It is important to determine as accurately as
  possible the condition of each element of the
  structure following the fire.
• Particular attention also needs to be given to
  those features which are an indirect consequence
  of the fire,
• eg forces not considered in the orginal design
  may have been generated by expansion or damage to
  other members.

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• Table 1 gives an approximate guide to the
  estimation of temperatures attained by various
  components in building fires, from an examination
  of debris.

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• The colouration of concrete at various depths is
  a clue to both the maximum surface temperature
  attained (Figure 1) and the time / temperature
  experience (Figure 2).
• Care and experince are required when considering
  spalled surfaces.
• The interpretation will depend on judgement as to
  whether spalling occured during the period of
  maximum heat exposure or subsequently, and as to
  the allowance to be made for this factor.
• The extent of the change of colour varies with
  the type of fine and coarse aggregate but changes
  will occur to some degree for all types of
  concrete.
• Wetting the affected concrete surface will
  enhance the colours. Some types of stone shows
  similar changes.

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• The depth of charring from the orginal surface
  gives a rough guide to the duration of fire
  attack on a timber member.
• Timber will char at a steady rate on each face
  exposed to heating.
• The rates which are given in Table 2 relate BS
  476Part 8 conditions and allow an assessment to
  be made in terms of an equivalent fire resistance
  time.
• Increased values are appropriate for the rate of
  depletion of columns and beams when exposed on
  all faces.
• Due allowance must be made for areas which have
  been allowed to smoulder after the fire has been
  controlled.

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• With palsterboard of 9.5 mm thickness, the
  unexposed paper face will be charred if there
  has been a fire equivalent in severity to about
  ten minutes under BS 476 Part 8 conditions.

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MAIN EFFECTS OF HIGH TEMPERATURE ON MATERIALS

• any material heated above 200oC is likely to show
  significant loss of strength which may, or may
  not, be recovered after cooling.

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Brickwork

• Clay bricks withstand temperature in the region
  of 1000oC or more without damage but under very
  severe and prolonged heating the surface of a
  brick may fuse.
• Spalling can occur with some types of brick
  particularly of the performed type.
• A load bearing wall exposed to fire will suffer a
  progressive reduction in strength due to
  deterioration of the mortar in the same manner as
  concrete.
• Severe damage is more likely to be caused by the
  expansion or collapse of other members.
• Small expansion cracks in the structure may
  collapse up after the building has cooled.

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Cast Iron

• Because of their heavy mass and low design
  stresses, cast iron members generally show good
  performance in fires.
• The member should be carefully examined for signs
  of cracking. A permanent loss of strength can
  occur when the temperature of a cast-iron member
  exceeds 600oC but because of their large thermal
  mass this requires a fire of such severity that
  rebuilding is probably necessary anyway.

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Concrete

• The behaviour of concrete structures in fire is
  discussed elsewhere5.6. The pink colour change at
  around
• 300oC which occurs with most natural aggregates
  used in the UK is very important as it coincides
  with the temperature below which the compressive
  strength is not significantly reduced. Higher
  temperatures up to approximately 500oC or above
  may be endured by lightweight concrete before
  significant loss of strength occurs. In a
  concrete member, only the temperature of the
  outside layers increases initially and the
  temperatures of the internal concrete will be
  comparatively low, unless the fire exposure is
  prolonged, as concrete is a poor conductor of
  heat (Figure 2). Temperature rise at a greater
  depth than indicated in that figure will occur if
  extensive spalling occurs during fire exposure.
  Natural aggregate concretes heated to
• 300oC or above, and lightweight aggregate
  concretes heated to 500oC or above, may need to
  be replaced in
• critical areas during reinstatement.

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Steel Reinforcement

• Looses strength at high temperatures as discussed
  below. Loss in effective concrete section in
  prestressed members may significantly alter the
  intended design stress profile in addition to
  permitting a higher temperature in any adjacent
  steel tendons with consequent increased loss.

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• Hollow clay tiles and woodwool cement slabs (used
  in floors)
• may be damaged but when these are used as formers
  for the structural concrete section they have no
  structural significance and the damage can be
  ignored.
• Plaster
• Plaster tends to be loosened in a fire and may
  require replacement for this reason.
• If it is severely stained by smoke which is
  resistant to washing, it will probably be more
  satisfactory to replace the plaster than to
  overpaint the smoke stains.

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Steel

• When a building has been exposed to fire the
  structural steelwork may suffer from any or all
  of the following effects
• a) expansion of heated members relative to
  others which restrain this movement, leading to
  distortion of the heated member or its neighbours
  particularly at connection,
• b) increased ductility, reduced strength and
  plastic flow while metal is at a high
  temperature,
• c) change, persisting after cooling, in the
  mechanical properties of the metal.
• The coefficient of linear thermal expansion of
  steel is nominally 14 X 10-6/0C. In a fire this
  may be sufficiently small for it to be taken up
  by elastic deformation, expansion joints etc, or
  may permanent distortion of the framework or
  extensive cracking of bearing walls.

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• The temperature at which the flow stress of mild
  steel falls to the design stress is generally
  taken to be about 550oC -
• for a design factor of safety of about 2. At
  stress levels less than the maximum permitted in
  design, this critical temperature will rise.
  The effects of constraints and continuity can
  also raise the critical temperature.
• Unless temperatures of 650oC are exceeded, there
  will be no deterioration in the mechanical
  properties of mild and micro-alloyed steels on
  cooling.
• After heating cold-drawn and heat-treated steels
  lose their strength more rapidly than mild and
  micro-alloyed steels and, on cooling from
  temperatures in excess of about 300oC and 400oC
  respectively, part of this loss of strength will
  be permanent.

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• In general, any steel members which have
  not distorted can be considered to be
  substantially unaffected by the heat to which
  they have been subjected. However, it must be
  realized that in certain cases some degradation
  in strength will have occurred.
• Members should be examined for cracks around
  rivet or bolt holes if expansion movements have
  taken place.
• It will usually however, be the cleast, rivets
  and especially bolts which will have suffered and
  not the main members.
• Decision on reinstatement may need to be taken in
  the light of expert engineering and metallurgical
  advice.

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• Tiles and slates
• Clay tiles that have survived a fire unbroken may
  be reused, as can slates that appear sound.
• Timber
• Behaviour of timber in fire is predictable with
  regard to the rate of charring and loss of
  strength.
• It is free from rapid changes of state and has
  very low coefficient of thermal expansion and
  thermal conductivity.
• For practical purposes, it can be assumed that
  full strength is maintained below the charred
  layer.
• For assessment of fire resistance of structural
  timber, BS 52683 provides calculation methods for
  flexural, compressive and tensile members.

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Woodwool cement

• The material below the crumbly fire damaged layer
  will be sound.
• If a sufficient depth of sound material is
  present the slabs may be retained.

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ASSESMENT OF EXTENT OF DAMAGE AND POSSIBLE
REINSTATEMENT

• A design procedure for the reinstatement of fire
  damaged buildings is given elswhere also a case
  study on building reinstatement.
• The problems caused by fire will of course
  include damage from water used in fire fighting
  as well as from heat and smoke.

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• The initial consideration of fire damaged
  premises should classify the damage to building
  components in terms of superficial, repairable or
  requiring replacement.
• In any investigation, it is essential to
  determine the exact form of construction of each
  element.
• Specialist advice may be needed in cases where
  there is much borderline repairable damage or
  where the construction is sophisticated.
• The final decision on the extent of repair or
  demolition may include consideration of costs,
  time and possible improvements.

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REFERENCES

• 1. British Standars Instution. Fire tests on
  building materials and structures. Test methods
  and criteria for the fire resistance of elements
  of building construction. BS 476 Part 81972
  London. BSI 1972
• 2. Bessey GE. Investigation on building fires.
  Part 2. The visible changes in concrete or mortar
  exposed to high temperatures. National Building
  Studies Technical Paper No 4 . London, HMSO,
  1950.
• 3. British Standards Instution. The structural
  use of timber. Fire resistance of timber
  structures. Method of calculating fire
  resisitance of timber members. BS 5268 Part 4.
  11978. London, BSI,
• 1978.
•  4. Lie T T. Fire and Buildings. Applied Science
  Publisher Ltd. London, 1978.
•  5. Asseement of fire damaged concrete structures
  and repair by gunite. Concrete Society Technical
•  Report No 15. The Concrete Society. London,
  1978.
•  6. Green J K. Some aids to the assessment of
  fire damage. Concrete. January, 1976.
•  7. Smith C I et al. The reinstatement of fire
  damage steel framed structures. British Steel
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