Building Construction - Snohomish County Fire Chiefs Association

concretecakeΠολεοδομικά Έργα

29 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

75 εμφανίσεις

6

Building
Construction

2

Objectives
(1 of 3)


Describe the characteristics of the
following building materials: masonry,
concrete, steel, glass, gypsum board,
and wood.

6

3

Objectives
(2 of 3)


List the characteristics of each of the
following types of building construction:
fire
-
resistive construction,
noncombustible construction, ordinary
construction, heavy timber construction,
and wood
-
frame construction.

6

4

Objectives
(3 of 3)


Describe how each of the five types of
building construction react to fire.


Describe the function of each of the
following building components:
foundations, floors, ceilings, roofs,
trusses, walls, doors, windows, interior
finishes, and floor coverings.

6

5

Introduction
(1 of 2)


Knowing building construction enables fire
fighters to:


Predict how a fire will spread


Make determinations about structural integrity


Recognize warning signs of imminent
collapse

6

6

Introduction
(2 of 2)


Fire risks also depend on occupancy
and contents.


Occupancy: how a building is used


Contents: vary, but usually related to
building use

6

7

Construction Material
Properties and Fire Behavior


Key factors affecting combustibility:


Combustibility


Thermal conductivity


Loss of strength when heated


Rate of thermal expansion

6

8

Types of Construction
Materials


Masonry


Concrete


Steel and other metals


Glass


Gypsum board


Wood


Plastics

6

9

Masonry


Inherently fire
-
resistive


Poor conductor of
heat


Openings can allow
fire to spread.


With prolonged
exposure to fire,
masonry can
collapse.

6

10

Concrete


Inherently fire
-
resistive


Poor conductor of heat


Strong under compression


Weak under tension


Can be damaged through exposure to
fire


Spalling

6

11

Steel
(1 of 2)


Strongest material in common use


Strong in both compression and tension


Will rust if exposed to air and moisture


Not fire
-
resistive


Good conductor of heat

6

12

Steel
(2 of 2)


Expands and loses
strength when
heated


Any sign of bending,
sagging, or
stretching indicates
immediate risk of
failure.

6

13

Other Metals


Aluminum


Often melts and drips in fires


Copper


Primarily used for piping and wiring


Zinc


Primarily used as a protective coating for
metals

6

14

Glass


Noncombustible, but not fire
-
resistive


Ordinary (non
-
treated) glass will break
when exposed to flame.

6

15

Gypsum Board

(1 of 2)


Not a strong structural material


Used mainly for finishing


Very good insulator


Limited combustibility


Paper will burn, but gypsum itself will
not.


Often used as a firestop

6

16

Gypsum Board

(2 of 2)


Prolonged exposure to fire will cause
failure.


Moisture in the material will evaporate
causing deterioration.

6

17

Wood


Most common building material


Highly combustible


Weakens when heated


Fire
-
retardant chemicals can weaken
wood.

6

18

Plastics


Rarely used for structural support


Combustibility varies


Many plastics release dense, toxic
smoke when they burn.


Thermoplastic materials melt and drip.


Thermoset materials lose strength but
will not melt.

6

19

Construction Type Determination


Classification based on combustibility
and fire resistance


Codes specify construction type
required based on:


Height


Area


Occupancy


Location

6

20

Types of Construction


Type I: Fire
-
Resistive


Type II: Noncombustible


Type III: Ordinary


Type IV: Heavy Timber


Type V: Wood Frame

6

21

Type I: Fire
-
Resistive
(1 of 2)


All structural
components must
be noncombustible.


Used for:


Large numbers of
people


Tall or large area


Special occupancies

6

22

Type I: Fire
-
Resistive
(2 of 2)


Building materials should not provide fuel for
a fire.


Contents may burn but the building should not.


Steel framing must be protected.


Fires can be very hot and hard to ventilate.


In extreme conditions Type I buildings can
collapse.

6

23

Type II: Noncombustible
(1 of 2)


All structural components
must be noncombustible.


Fire
-
resistive
requirements are less
stringent than Type I.

6

24

Type II: Noncombustible
(2 of 2)


Structural components contribute little
or no fuel.


Fire severity is determined by contents.


Most common in single
-
story
warehouses or factories

6

25

Type III: Ordinary

(1 of 2)


Used in a wide range
of buildings


Masonry exterior walls
support floors and roof.


Usually limited to no
more than four stories


Limited fire resistance
requirements

6

26

Type III: Ordinary

(2 of 2)


Two separate fire loads:


Construction materials


Contents


Fire resistance depends on building
age and local building codes.


Exterior walls, floors, and roof are
connected.

6

27

Type IV: Heavy Timber

(1 of 2)


Exterior masonry
walls


Interior structural
elements, floors,
and roof of wood

6

28

Type IV: Heavy Timber

(2 of 2)


No concealed spaces or voids


Used for buildings as tall as eight
stories


Open spaces suitable for
manufacturing and storage


New Type IV construction is rare.

6

29

Type V: Wood Frame
(1 of 3)


Most common type of
construction in use


All major components
are wood or other
combustible materials.


Can rapidly become
fully involved


Collapse frequently

6

30

Type V: Wood Frame
(2 of 3)


Used in buildings of up to four stories


Wooden I
-
beams and trusses


Just strong enough to carry required load


No built
-
in safety margin


Collapse early and suddenly

6

31

Type V: Wood Frame
(3 of 3)


Balloon
-
frame
construction


Exterior walls assembled
with continuous wood
studs from the basement
to the roof.


Platform
-
frame
construction


Exterior wall studs not
continuous.


6

32

Building Components


Foundation


Floors and ceilings


Roofs


Trusses


Walls


Doors and windows


Interior finishes and floor coverings

6

33

Foundation


Ensures building is
firmly planted


Helps keep all other
components
connected


Weak or shifting
foundations can
cause collapse.

6

34

Floors and Ceilings
(1 of 2)


Fire
-
Resistive Floors


Floor
-
ceiling system designed to prevent
vertical fire spread


If space above ceiling is not partitioned or
sprinklered, fire can quickly extend
horizontally across a large area.

6

35

Floors and Ceilings

(2 of 2)


Wood
-
Supported Floors


Heavy
-
timber floors can often contain a
fire for an hour or more.


Conventional wood flooring burns readily
and can fail in as little as 20 minutes.


Modern, lightweight wood I
-
beams and
trusses


Little fire resistance

6

36

Roofs


Not designed to be as strong as floors


Three primary designs:


Pitched roofs


Curved roofs


Flat roofs

6

37

Pitched Roofs


Sloped or inclined


Can be gable, hip,
mansard, gambrel,
or lean
-
to


Usually supported
by rafters or trusses


Require some sort
of roof covering

6

38

Curved Roofs


Used for large buildings that require
large, open interiors


Supermarkets


Warehouses


Industrial buildings


Usually supported by bowstring
trusses or arches

6

39

Flat Roofs

(1 of 2)


Usually found on
houses, apartment
buildings,
warehouses,
factories, schools,
and hospitals


Have a slight slope
for drainage


Wood support
structures use solid
wood beams and
joists.

6

40

Flat Roofs

(2 of 2)


Lightweight construction techniques
employ wood I
-
beams and trusses.


Open
-
web steel trusses (bar joists)
often used for support


Most coverings highly combustible


Ventilation may involve cutting through
many layers of roofing.

6

41

Trusses

(1 of 2)


Triangular geometry creates a strong,
rigid structure.


Usually prefabricated wood or steel


Three types:


Parallel chord


Pitched chord


Bowstring

6

42

Trusses

(2 of 2)


Parallel chord


Used for flat roofs and floors


Pitched chord


Used for pitched roofs


Bowstring


Used for curved roofs

6

43

Walls


Most visible part of a building


Constructed of a variety of materials


Walls are:


Load
-
bearing


Nonbearing


Specialized

6

44

Load
-
Bearing Walls


Give structural support


Either interior or
exterior


Support both “dead
load” and “live load”


Damaged wall can
result in collapse

6

45

Nonbearing Walls


Support only their
own weight


Can be breached or
removed without
compromising
structural integrity


Either interior or
exterior

6

46

Specialized Walls
(1 of 2)


Party walls


Common to two properties


Almost always load
-
bearing


Often a fire wall


Fire walls


Designed to limit horizontal fire spread


Extend from foundation through roof


Constructed of fire
-
resistant materials

6

47

Specialized Walls
(2 of 2)


Fire partitions


Interior walls that extend from a floor to underside
of floor above


Fire enclosures


Fire
-
rated assemblies that enclose vertical
openings


Curtain walls


Nonbearing exterior walls attached to the outside
of a building

6

48

Walls


Solid, load
-
bearing masonry walls can
reach six stories high.


Nonbearing masonry walls can reach
almost any height.


Never assume that exterior walls are
masonry.

6

49

Doors


Can be used for entry, exit, light, and
ventilation


Mostly constructed of wood or metal


Hollow
-
core wood doors offer little fire
resistance.


Solid
-
core doors provide some fire
resistance.


Metal doors more durable and fire
-
resistant.

6

50

Window Assemblies


Used for light,
ventilation, entry,
and exit


Window type
depends on a
variety of factors.

6

51

Fire Doors and Fire Windows

(1 of 2)


Constructed to prevent
spread of flames, heat,
and smoke


Must meet NFPA 80


Labeled according to
approved
-
use


Class A


Class B


Class C


Class D


Class E

6

52

Fire Doors and Fire Windows

(2 of 2)


Fire windows are
used when a
window is needed
in a required fire
-
resistant wall.

6

53

Interior Finishes

and Floor Coverings


Finishes and coverings are exposed
interior surfaces of a building.


Different interior finish materials
contribute in various ways to a building
fire.

6

54

Construction or Demolition


Construction or demolition sites pose
special problems for fire fighters.


Built
-
in fire protection features are often
missing.


Fire
-
resistive enclosures can be
missing.


Often unoccupied for long periods

6

55

Summary
(1 of 2)


Many materials are used in building
construction, and each material reacts
differently to heat and fire.


The five types of building construction
each have their own strengths and
weaknesses and differing levels of
resistance to fire.

6

56

Summary
(2 of 2)


Buildings contain a variety of parts or
components.


Materials used in building components
vary.

6