Transcript OFFICE OF THE STATE FIRE MARSHAL Building Construction

OFFICE OF THE STATE FIRE
MARSHAL
Building Construction
OBJECTIVES

2-9.1 Identify the basic structural
characteristics of the following types of
building construction: (3-3.11)
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2-9.1.1
2-9.1.2
2-9.1.3
2-9.1.4
2-9.1.5
Fire resistive (Type I)
Noncombustible (Type II)
Ordinary (Type III)
Heavy timber (Type IV)
Wood frame (Type V)
OBJECTIVES

2-9.2 Identify the two basic types of
light wood framing.
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2-9.1 Balloon framing
2-9.2 Platform framing
2-9.3 Identify the main components of
lightweight framing construction.
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2-9.3.1
2-9.3.2
Footing
Foundation
OBJECTIVES
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2-9.3.3
2-9.3.4
2-9.3.5
2-9.3.6
2-9.3.7
2-9.3.8
2-9.3.9
2-9.3.10
Plate
Stud
Joist
Rafter
Sill
Header
Ridge Board
Eave
OBJECTIVES
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2-9.3.11
2-9.3.12
2-9.3.13
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2-9.3.13.1 Plaster
2-9.3.13.2 Drywall
2-9.3.14
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Fascia
Soffit
Interior finish
Exterior finish
2-9.3.14.1 Brick veneer
2-9.3.14.2 Sheathing
OBJECTIVES

2-9.4 Identify the three, broadly
classified, categories of roofs from a
firefighting standpoint.
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2-9.4.1
2-9.4.2
2-9.4.3
Flat roofs
Pitched roofs
Curved roofs
OBJECTIVES
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2-9.5 Identify structural components
of large structural systems.
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2-9.5.1
2-9.5.2
2-9.5.3
2-9.5.4
2-9.5.5
Beams
Columns
Arches
Cables
Trusses
OBJECTIVES
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2-9.6 Identify the components of
truss construction.
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2-9.6.1
2-9.6.2
2-9.6.3
Chords
Web or diagonal members
Gusset plate
2-9.7 Identify three hazards
associated with truss and lightweight
construction. (3-3.11)
OBJECTIVES
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2-9.7 Identify dangerous building
conditions created by fire and fire
suppression activities. (3-3.9, 3-3.11)
2-9.8 Identify the term “building
collapse”. (3-3.9, 3-3.11)
2-9.9 Identify five indicators of building
collapse. (3-3.9, 3-3.11)
OBJECTIVES

2-9.11 Identify the effects of fire and fire
suppression activities on the following
building materials. (3-3.9, 3-3.11)
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2-9.11.1
2-9.11.2
2-9.11.3
2-9.11.4
2-9.11.5
2-9.11.6
2-9.11.7
2-9.11.8
Wood
Masonry
Cast iron
Steel
Reinforced concrete
Gypsum wallboard
Glass
Plaster on lath
OBJECTIVES
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2-9.11 Identify the following terms as they
relate to building construction: (3-3.11)
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2-9.12.1
2-9.12.2
2-9.12.3
2-9.12.4
2-9.12.5
2-9.12.6
2-9.12.7
Load bearing wall
Non-load-bearing wall
Party wall
Fire wall
Partition wall
Cantilever or unsupported wall
Parapet wall
OBJECTIVES
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2-9.13 Identify the effects of the
following items in a burning building:
(3-3.9, 3-3.11)
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2-9.13.1
Intense heat
2-9.13.2
Dense smoke
2-9.13.3
Large volume of water pour onto
and into structure
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IFSTA, Essentials, 4th ed, Chapter 3
Delmar, Firefighter Handbook, 2000, Chapter 13
BASIC STRUCTURAL
CHARACTERISTICS
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Fire Resistive (Type I)
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Structural members are noncombustible or
limited combustible materials.
Primary hazard contents.
Ability to confine fire compromised by
openings.
A beam being placed on columns. The beams are notched to accept the double Ts.
A double T being lowered into place on the beams
The double Ts are notched to fit onto the beams and
are held in place by their weight.
Flammable liquids from ruptured fuel tanks can
travel to lower levels through penetrations in the
deck.
A parking deck attached to an office building.
Parking decks can be found on top of or below occupied spaces. In this
building, the first several floors of the structure are parking deck topped
with offices.
A stand-alone parking deck.
Stairways in parking decks are often open. Expect
heavy smoke conditions.
First interstate Bank Building (Los Angles ) Fire resistive type I construction ( believe it or not!)
Photo by: New York Board of Underwriters
BASIC STRUCTURAL
CHARACTERISTICS
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Noncombustible (Type II)
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Similar to fire resistive (Type I); only degree of fire
resistance is less.
In some cases, materials with no fire resistance
may be used.
Primary hazard contents
Heat buildup, during a fire, may cause structural
supports to fail.
Type of roof material may contribute to fire
extension.
BASIC STRUCTURAL
CHARACTERISTICS
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Ordinary (Type III)
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Exterior walls and structural members are
noncombustible or limited combustible materials.
Interior structural members completely or partially
of wood.
Wood used has smaller dimensions than Type IV.
Primary hazard is fire and smoke spread through
concealed spaces.
BASIC STRUCTURAL
CHARACTERISTICS
A view of ordinary
construction
from the street.
The same
building. You
can see the
header
courses of
brick by
looking down
the side.
Always look
at as many
sides of the
building as
possible to
determine
construction,
occupancy,
and floor.
Ordinary type III
Construction
Photo by: Warren
Fuchs Brooklyn
Dispatcher
BASIC STRUCTURAL
CHARACTERISTICS
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Heavy timber (Type IV)
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Exterior and interior walls and associated structural
members are noncombustible or limited combustible
materials.
Other interior structural members are made of solid or
laminated wood with no concealed spaces.
Wood has large enough dimensions to be considered heavy
timber.
Primary hazard: the combustible contents of the structural
members.
Because of the amount of heat given off by the structural
members, the building may pose serious exposure protection
problems.
BASIC STRUCTURAL
CHARACTERISTICS
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Wood frame (Type V)
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All walls and structural supports are made
completely or partially of wood of
dimensions less than heavy timber.
Presents unlimited potential for fire spread.
May present a serious exposure problem
especially if exposures are of similar
construction.
The Outer Shell
LIGHT WOOD FRAMING
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Balloon framing
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Construction can have open channels from
the foundation to the attic.
Framing is usually covered with an interior
finish of plaster or drywall.
This balloon-frame structure can easily be
recognized by the roofline façade. Because of
the fire escapes on the “B” side , anticipate
that there are front and rear apartments on
each floor where there should be only one
large unit. The floor plan will also be different
from what you would normally find.
The building industry calls these cross braces firestopping. In fact, their purpose is to
brace the stud (which is a column receiving compressive loads) at about midpoint, thus
greatly increasing its load-carrying capacity. Their firestopping value is incidentalfirestopping should cut off the wall voids from the floor voids.
LIGHT WOOD FRAMING
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Platform framing
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Construction has each floor constructed on
its own platform, reducing open channels
in the wall.
Framing is usually covered with an interior
finish of plaster or drywall.
LIGHTWEIGHT FRAMING
CONSTRUCTION
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Footing: That part of the building that
rests on the bearing soil and is wider
than the foundation wall. Also the base
for a column. It spreads the weight of
a wall or column and presents settling.
Foundation: The supporting part of a
wall usually of masonry or concrete and
at least partially underground.
Foundation Footings
Stepped footing can support a concrete block wall. Blocks have nominal
dimensions of 8 by 8 by 16 inches (the actual dimensions are actually 3/8
inch smaller than these to allow for mortar joints). They are hollow when
laid-up; steel reinforcing bar called rebar is added and the hollows in the
blocks are often filled with concrete. They lend themselves to construction
where forming concrete is difficult or impractical.
Concrete blocks are also used for standard foundation wall construction.
Here they are supported by a concrete footing; both are reinforced with
steel rods and the concrete blocks are filled with grout.
A concrete pier, resting on a footing, may be used to help support beams
at mid-span. Though some older homes rest entirely on piers, this method
has been phased out in favor of stronger foundations.
LIGHTWEIGHT FRAMING
CONSTRUCTION
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Plate: The top or bottom horizontal
structural member of a frame wall or
partition.
Stud: Vertical structural uprights
which make up the walls and partitions
in a frame building.
Joist: A framing member which
directly supports the floor.
LIGHTWEIGHT FRAMING
CONSTRUCTION
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Rafter: A beam that supports a roof.
Sill: The bottom rough structural
member that rests on the foundation or
the bottom exterior member of a
window or door or other masonry below.
Head: The top of a window or
doorframe.
LIGHTWEIGHT FRAMING
CONSTRUCTION
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Ridge Board: The horizontal timber or
beam at the ridge of a roof, to which
the upper ends of the rafters are
attached.
Eave: The lower edge of a roof,
usually projecting beyond the sides of a
building.
LIGHTWEIGHT FRAMING
CONSTRUCTION
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Cornice: A horizontal projection that
crowns or finishes the eave of a
building.
Fascia: A flat vertical board located at
the outer face of a cornice.
Soffit: A lower horizontal surface such
as the undersurface of eaves or cornice.
Fascia and Soffit
LIGHTWEIGHT FRAMING
CONSTRUCTION
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Interior finish
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Plaster:
A fire-resistive cement
material that is applied over lathing, which
is either a wire mesh or a gypsum board
with a fibrous paper.
Drywall:
A system of interior wall finish
using sheets of gypsum board and taped
joints.
LIGHTWEIGHT FRAMING
CONSTRUCTION
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Exterior finish
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Brick veneer:
Single thickness of brick
wall facing placed over frame construction
or masonry other than brick.
Sheathing:
Covering applied to the
framing of a building to which siding is
applied.
Brick veneer
The brick wall is connected to the wooden wall by thin steel
tabs nailed to the wall.
ROOFS
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Flat roofs
Pitched roofs
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Gable roofs
Hip roofs
Gambrel roofs
Mansard roofs
Shed roofs
Butterfly roofs
Monitor roofs
Saw tooth roofs
Curved roofs
LARGE STRUCTURAL
SYSTEMS
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Beams:
A structural member subjected to loads
perpendicular to its length.
Columns: A vertical supporting member.
Arches:
Curved structural member in which the
interior stresses are primarily compressive. Arches
develop inclined reactions at their support.
Cables:
Flexible structural members in which the
stresses in the cable are tension stresses.
Trusses: Framed structural units made of a group of
triangles in one plane.
TRUSS CONSTRUCTION
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Chords: Top and bottom horizontal
members of a truss.
Web or diagonal members: Vertical
members between the chords.
Gusset plate: Plate that is used to
connect the members of a wood or
metal truss.
Photo R275 - The bottom chord of this truss is under a tensile (pulling) load when in place.
It consists of three pieces of wood with four gusset plate connectors. When the gusset plate heats
up, the heat is transferred to the teeth by conduction. The heated teeth destroy the wood fibers in
tension which were gripping the teeth. It is called pyrolytic decomposition, burning without flame
as occurs when you burn the company number into an axe handle.
Photo R244 - This construction illustrates the value of trusses.
To build a conventional building this wide would have required
heavy roof beams or bothersome interior columns.The walls
would need to be much heavier to carry the weight of the long
rafters.The truss provides clear spans at low cost. Know your
buildings and use the thermal imager (Firefighter’s Radar) to
detect hidden fire.
HAZARDS ASSOCIATED WITH TRUSS
& LIGHTWEIGHT CONSTRUCTION
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Designed to support only own weight
If one fails, a domino effect usually
occurs until total collapse has resulted.
Rapid failure under fire conditions:
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Usually 5 to 10 minutes
Wood – ¼ inch char
Steel 1000 degree F.
DANGEROUS CONDITIONS CREATED
BY FIRE & FIRE SUPRESSION
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Two primary types of dangerous
conditions.
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Conditions that contribute to the spread and
intensity of the fire.
Conditions that make the building susceptible
to collapse.
DANGEROUS CONDITIONS CREATED
BY FIRE & FIRE SUPRESSION
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Conditions that contribute to the spread and
intensity of the fire.
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Fire loading
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Presence of large amounts of combustible materials in an
area of a building.
Arrangement of combustible materials in a building.
Combustible furnishings and finishes
Roof coverings
Wooden floors and ceilings
Patrons attempted to leave by the hallway to the club's front door, but the exit there
soon grew choked. Most of the crowd apparently attempted to leave through that
exit, fire officials said.
The rush to exit the front left a pile of people, trapped in the burning building. Fire
officials estimated the number of people inside as less than 300, the club's official
capacity.
Rescuers attempted to pull people from the front door pile.
According to authorities, most of the bodies later found were near
the front door.
Within minutes, the building was in flames. Firefighters fought the
blaze in vain but were able to rescue some people inside.
DANGEROUS CONDITIONS CREATED
BY FIRE & FIRE SUPRESSION
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Large open spaces
Building collapse
Lightweight and truss construction
Construction, renovation and demolition
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A trained eye would detect that this Suburban
Hospital Bethesda MD Outpatient Center is a post
tensioned concrete construction job and all that
dry hard concrete is not attached to the building
and is supported only by the fire vulnerable
wooden falsework Smoke might obscure vision so
the only sound precaution is for the FD to be aware
on a daily basis of this deadly type of construction.
Void Spaces
Roof Coverings
BUILDING COLLAPSE
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Resulting from damage to the structural
system of the building caused by the fire or
by firefighting operations.
Most likely time when firefighters are killed or
injured.
Most likely time when R.I.T. is put into action.
When Building Collapse is evident or possible,
operations should be made from the corners
of the buildings!!
April 2004 Ebenezer
Baptist
Church Pittsburgh, PA
Collapse Zone
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1 ½ times the
height of the
building.
INDICATORS OF BUILDING
COLLAPSE
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Cracks or separations in walls, floors, ceilings
and roof structures.
Evidence of existing structural instability such
as the presence of tie rods.
Stairs that hold the wall together
Loose bricks, blocks or stones falling from the
building
Deteriorated mortar between the masonry.
Walls that appear to be leaning in one
direction or another
INDICATORS OF BUILDING
COLLAPSE
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Are there any of these signs on
buildings in your town?
Bet you there are!
INDICATORS OF BUILDING
COLLAPSE
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Structural members that appear to be
distorted or pulling away from the walls
Fires beneath floors that support heavy
machinery or other extreme weight
loads.
Prolonged fire exposure to the
structural members.
Unusual creaks and cracking noises.
EFFECTS OF FIRE & FIRE
SUPPRESSION
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Wood – reaction depends on size of the
wood component. (The smaller the
size, the more likely to lose integrity
Type IV Construction v. Type V
Construction)
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Moisture content of wood (old v. new)
Application of water has no adverse impact
on
(11) Lightweight floor construction will not withstand more than a few minutes of fire exposure and cannot support a company advancing
through the front door. A basement fire may have to be attacked from a window or an outside entrance. (Photo by Lazaro Acosta.)
EFFECTS OF FIRE & FIRE
SUPPRESSION
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Masonry
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Minimally affected by fire (heat).
Mortar between masonry components subject to
more deterioration and weakening from fire.
Rapid cooling may cause some masonry
components such as bricks, blocks or stone to
spall.
Masonry components should be inspected after
extinguishment to determine signs of damage.
EFFECTS OF FIRE & FIRE
SUPPRESSION
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Cast Iron
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Found only in older buildings.
Bolts and other fastening devices may fail when
exposed to fire, permitting large sections of cast
iron walls to fall.
Steel
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Members elongate when heated (50 ft beam may
elongate 4 inches when heated to 1000 degrees F.
If ends are restrained, it will buckle or fail
somewhere in the middle.
Failure can be anticipated at 1000 degrees F.
EFFECTS OF FIRE & FIRE
SUPPRESSION
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Reinforced concrete
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Loses strength and spalls.
Heat may cause failure of bond between concrete
and steel reinforcement.
Gypsum wallboard
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Excellent heat-resistant and fire-retardant
properties.
Will gradually break down under fire conditions.
Members protected by gypsum could be exposed
to high temperatures if gypsum fails.
EFFECTS OF FIRE & FIRE
SUPPRESSION
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Glass/fiberglass
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Glass does not contribute to the fire load,
but resins used in fiberglass will.
Heated glass may crack when hit by a fire
stream.
Plaster on lath
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Similar to gypsum
Large sections may fall during firefighting
operations.
TERMS
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Load-bearing wall: walls that support
structural weight
Non-load-bearing wall: walls that do not
support structural weight.
Party wall: load-bearing wall that
supports two adjacent structures
Load-Bearing Walls
Exterior walls that carry ceiling, roof or upper floor loads to the foundation are load bearing or "bearing" walls. Internal walls that support joists at mid span
and transfer loads down to foundations are also bearing walls. Bearing walls usually have perpendicular joists or rafters crossing or resting on top of them and
foundations underneath them. An exception are the end walls of a gable-roofed house; these usually run parallel to rafters and joists but must bear the weight
of extensive wall framing.
Wind and seismic loads, which produce lateral stresses on a house, are managed by tightly interlocking framing members. Plywood sheathing or wood or metal
crossbracing interconnect framing members, creating a sturdy triangular form and-together with foundation bolts-lock walls to foundation. The roof is
protected from wind uplift by steel strapping.
TERMS
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Fire wall: separates two structures,
or divides a structure into smaller
portions to prevent the spread of
fire.
Partition wall: non-load-bearing
wall that divides two areas within
a structure.
Cantilever or unsupported wall:
freestanding firewall usually found
in shopping centers or churches.
Parapet wall: low wall at the edge
of a roof.
EFFECTS IN A BURNING
BUILDING
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Intense heat
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Causes access problems to firefighters during
operations
Contributes to fire spread
Dense smoke
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Hampers firefighting operations
Proper ventilation is required to ensure:
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Removal of smoke
Stability of building
EFFECTS IN A BURNING
BUILDING
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Large volume of water
poured into and on the
structure
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Compromises integrity of
construction materials
Accumulation of water on
the upper floors or roof will
add to the live load of an
already weakened structure.