6742 Ch 5 PowerPoint

1. Fire Department Incident Safety
Officer
Third Edition
Chapter 5 — Reading Buildings

2. Knowledge Objectives (1 of 2)
‣ Describe the relationship of loads and load imposition on a
building.
‣ List the three types of forces created when loads are
imposed on materials.
‣ Describe the effect that fire has on building materials,
loads, and forces.
‣ Define columns, beams, and connections.
‣ List and define the influences used for building construction
classifications.
‣ Define and list several types of hybrid buildings.

3. Knowledge Objectives (2 of 2)
‣ State the structural collapse hazards of common building
construction classifications.
‣ List, in order, the five-step analytical approach to predicting
building collapse.
‣ Describe the structural collapse indicators present at an
incident scene.
‣ Describe the additional structural collapse indicators present
after a collapse has occurred.
‣ Identify the structural collapse issues that should be
communicated to the rapid intervention crew by the
incident safety officer.

4. ‣ Incident safety officers must be able to give explicit detail and
their judgment regarding the collapse potential of a given
building being attacked by fire
‣ The ISO needs to communicate building construction
considerations and observations
‣ The ISO must draw from a significant knowledge base to make
collapse judgments
Introduction: The Collapse Warning (1 of 3)

5. Introduction: The Collapse Warning (2 of 3)
‣ The Ol’ Professor
‣ Francis L. Brannigan
‣ Coined many powerful—and lifesaving—phrases:
‣ “The building is the enemy—know your enemy.”
‣ “Beware the truss!”
‣ “The bottom chord of a truss is under tension—it’s like
you hanging on a rope. If the rope gets cut, you will fall.”
‣ “The slightest indication of column failure should cause
the building to be cleared immediately.”

6. Introduction: The Collapse Warning (3 of 3)
‣ The Ol’ Professor (cont.)
‣ “From an engineering point of view, [lightweight]
buildings are made to be disposable….We don’t make
disposable firefighters!”
‣ “The warning is the brain—in your ability to understand
buildings and anticipate how they will react to fire.”
‣ The Brannigan student
‣ Better prepared to identify and analyze buildings
‣ Makes better judgements

7. Essential Building Construction Concepts
‣ Predicting Building Collapse
‣ Dependent on the application of essential building
construction concepts
‣ Smoke and fire observations
‣ ISOs must apply skill to predict and communicate collapse
potential
‣ ISOs must establish collapse zones

8. Imposition and Resistance of Loads (1 of 3)
‣ Types of loads
‣ Dead load
‣ Live load
‣ Loads can be imposed three
ways:
‣ Axially
‣ Eccentrically
‣ Torsionally

9. ‣ Three types of forces
created by imposed
material resisting the load:
‣ Compression
‣ Tension
‣ Shear
Imposition and Resistance of Loads (2 of 3)

10. Courtesy of David Dodson
‣ Structure of an all-steel
building
Imposition and Resistance of Loads (3 of 3)

11. Characteristics of Building Materials (1 of 7)
‣ A receiving material must resist and transfer force
‣ A material’s response to applied force depends on its load-
bearing characteristics
‣Ductile: bends before it breaks
‣Brittle: breaks before it bends
‣ The fire service looks at mass and fire resistance
‣Surface-to-mass ratio
‣Mass is heat resistance, and heat resistance is time

12. Characteristics of Building Materials (2 of 7)

13. ‣ Types of materials
‣ Wood
‣ Native wood is wood cut from a tree
‣ Engineered wood consists of many pieces of native wood
(chips, veneers, and sawdust) glued together to make a
sheet, beam, or column
‣ Glues that bind it require only heat to break down
Characteristics of Building Materials (3 of 7)

14. ‣ Types of materials
‣ Steel
‣ Ductile material that has excellent tensile, shear, and
compressive strength
‣ Girders, lintels, cantilevered beams, and columns
‣ In a fire, steel loses strength and deforms as
temperatures increase
Characteristics of Building Materials (4 of 7)

15. ‣ Types of materials
‣ Concrete
‣ Mixture of Portland cement, sand, gravel, and water
that cures into a solid mass
‣ Steel is often added as reinforcement
‣ All concrete contains moisture
‣ When heated, this moisture content expands,
causing concrete to crack or spall
Characteristics of Building Materials (5 of 7)

16. ‣ Types of materials
‣ Masonry
‣ Brick, concrete brick, and stone
‣ Used to form load-bearing walls, but can also be used
to build a veneer wall that supports only its own weight
‣ During a fire, masonry blocks can absorb more heat
than the mortar used to bond them, creating different
heat stresses that can crack the mortar
Characteristics of Building Materials (6 of 7)

17. ‣ Types of materials
‣ Composites
‣ Refers to a combination of the four basic materials as
well as various plastics, adhesives, and assembly
materials
‣ Engineered wood products are widely used for
structural elements
Characteristics of Building Materials (7 of 7)

18. Structural Elements (1 of 4)
‣ Columns
‣ Transmit a compressive
force axially through the
center
‣ Typically support beams
and other columns
Courtesy of David Dodson Courtesy of David Dodson

19. ‣ Beams
‣ Structural element that transfers loads perpendicularly
‣ Loads placed on a beam create opposing forces
‣ The top of the beam is subjected to a compressive force
while the bottom of the beam is subjected to tension
Structural Elements (2 of 4)

20. ‣ Beams (cont.)
‣ Some beam types:
‣ Simple, continuous, cantilever, lintel, girder, joist, truss,
purlin
‣ Conventional construction has solid wood or steel beams in
the floors and roofs
‣ Open-webbed beams are called truss construction
Structural Elements (3 of 4)

21. ‣ Connections
‣ Structural element used to attach other structural elements
to one another
‣ “Weak link” in structural failure during fires
‣ There are three general types of connections:
‣ Pinned connections
‣ Rigid connections
‣ Gravity connections
Structural Elements (4 of 4)

22. Construction Classifications (1 of 9)
‣ Categorizing by building type
‣ Type I: Fire Resistive
‣ Structural elements are of an approved noncombustible
or limited combustible material with sufficient fire-
resistive ratings to withstand the effects of fire and
prevent its spread from story to story
‣ High-rises, megamalls, large stadiums and arenas, large
parking garages, and larger hospitals

23. ‣ Categorizing by building type
‣ Type II: Noncombustible
‣ Structural elements do not qualify for Type I
construction
‣ Approved noncombustible or limited-combustible
materials
‣ More often than not, Type II buildings are steel
‣ Fire spread in Type II buildings is influenced by the
contents
Construction Classifications (2 of 9)

24. ‣ Categorizing by building type
‣ Type III: Ordinary
‣ Load-bearing walls are noncombustible (masonry) and
the roof and floor assemblies are wood
‣ Primary fire and collapse concerns with ordinary
construction are the many void spaces in which fire can
spread undetected
‣ Masonry walls hold heat inside, making for difficult
firefighting
Construction Classifications (3 of 9)

25. ‣ Categorizing by building type
‣ Type IV: Heavy Timber
‣ Buildings that have block or brick
exterior load-bearing walls and
interior structural elements of a
substantial dimension
‣ Cost of lumber makes this type of
construction rare
‣ Fire spread in a heavy timber
building can be fast due to wide-
open areas and content exposure
Courtesy of David Dodson
Construction Classifications (4 of 9)

26. ‣ Categorizing by building type
‣ Type V: Wood Frame
‣ Perhaps the most common construction type
‣ Primary concern is that they are made from a
combustible material
‣ Fire and heat that penetrate or degrade the protective
drywall wall will then attack the wooden elements,
creating a collapse threat, especially in newer buildings
‣ Other construction types
‣ Hybrid buildings
Construction Classifications (5 of 9)

27. ‣ Categorizing by building era
‣ Significant changes in the history of building construction
‣ Founder’s era: 1700s to WWI
‣ Alterations made as utilities improved
‣ Open/narrow stairways and hallways
‣ Minimal fire code requirements
‣ Industrial era: WWI to WWII
‣ Balloon framing for wood buildings
‣ Open hallways and stairways
‣ Larger roof spans – unprotected steel
Construction Classifications (6 of 9)

28. ‣ Categorizing by building era
‣ Legacy era: WWII to roughly 1980
‣ Durable strength
‣ Better fire/building code requirements
‣ More-reliable utility systems
‣ Lightweight era: 1980s to present
‣ Prescriptive to performance-based codes
‣ Ever-increasing heat-release rate
‣ High surface-to-mass = rapid collapse
Construction Classifications (7 of 9)

29. ‣ Categorizing by building use
‣ Some groupings
‣ Single-family dwellings
‣ Multiple-family dwellings
‣ Offices/hotels
‣ Commercial retail
‣ Manufacturing/warehouses
‣ Schools/hospitals
‣ Public assemblies (stadiums/arenas/theaters/churches)
‣ Mixed/miscellaneous use
Construction Classifications (8 of 9)

30. ‣ Categorizing by building size
‣ Size elements
‣ The footprint, or single floor, square footage of a
building (width, length/depth)
‣ The interior arrangement of walls and the volume of
space for any one room
‣ The number of floors above ground and basement
levels below
‣ The distance that must be traveled to reach a fire or
potential victims
Construction Classifications (9 of 9)

31. Predicting Collapse (1 of 11)
‣ Collapse model
‣ “Identify–analyze–decide” method
‣ Five-step process
‣ Steps 1 and 2 are when the identification takes place
‣ Steps 3 and 4 are analytical
‣ Step 5 is when the decision (regarding collapse) is
made and communicated

32. ‣ Step 1: Classifying the building’s construction
‣ Using the type/era/use/size approach helps the ISO:
‣ Identify the strengths and weaknesses
‣ Interpret how the materials and arrangement of structural
elements might be impacted by fire and heat
Predicting Collapse (2 of 11)

33. ‣ Step 2: Determining structural involvement
‣ Determining whether a fire is a contents or structure fire is
imperative
‣ Structure fire
‣ Load-bearing components are being attacked
‣ Fires that can become “structural”
‣ Fire in concealed spaces
‣ Content fire in unfinished basements
‣ Attic fires
‣ Heated exposed beam or truss
Predicting Collapse (3 of 11)

34. ‣ Step 2: Determining structural involvement
Courtesy of David Dodson
Predicting Collapse (4 of 11)

35. ‣ Step 3: Visualizing and tracing loads
‣ More an art than a science
‣ Is analytical
‣ ISO visually scans the building
‣ Determines any structural element carrying something
it should not
‣ Concludes whether key elements are being attacked by
fire and/or heat
‣ Mentally “undresses” a building to define weak links
Predicting Collapse (5 of 11)

36. ‣ Step 3: Visualizing and tracing loads (cont.)
‣ Common weak links:
‣ Connections
‣ Overloading
‣ Occupancy conversion
‣ Trusses
‣ Large, open-span Interiors
‣ Parapet walls/facades
Predicting Collapse (6 of 11)

37. ‣ Step 4: Evaluating time
‣ Factors that can accelerate the potential collapse time
‣ Low material mass or high surface-to-mass ratio
‣ An imposed overload
‣ Higher British thermal unit (Btu) development (fire
load)
‣ Alterations (undesigned loading)
‣ Age deterioration or the lack of care and maintenance
of the structure
‣ Firefighting impact loads
Predicting Collapse (7 of 11)

38. ‣ Step 4: Evaluating time (cont.)
‣ Some time truisms
‣ The lighter the structural elements, or heavier the
imposed load, the faster the structure comes down
‣ Wet (cooled) steel buys time
‣ Gravity and time are constant; resistance is not
‣ Brown or dark smoke coming from lightweight
engineered wood products means that time is up
‣ Trusses system recommendation
‣ NIOSH (Publication No. 2005-1432)
Predicting Collapse (8 of 11)

39. ‣ Step 5: Predicting and communicating the collapse potential
‣ “Decision” part of the identify–analyze–decide model
‣ Collapse potential
‣ Deterioration and cracks of mortar joints and
masonry
‣ Signs of building repair
‣ Bulges and bowing of walls, sagging floors and
roofs
‣ Buildings under construction, renovation, or
demolition
‣ Large volumes of fire impinging on structural
components
‣ Doors out of plumb or jammed
Predicting Collapse (9 of 11)

40. ‣ Step 5: Predicting and communicating the collapse potential
(cont.)
‣ Communicate to command
‣ Establishment of a collapse zone
‣ Specific form of a no-entry zone for anyone—
including firefighters
‣ 1½ to 3 times the height of the structure
Predicting Collapse (10 of 11)

41. ‣ Step 5: Predicting and communicating the collapse potential
(cont.)
‣ Type of collapse
‣ Partial collapse
‣ General collapse
‣ Secondary collapse
‣ Communication options
‣ Emergency evacuation
‣ Precautionary withdrawal
‣ Planning awareness
Predicting Collapse (11 of 11)