Chapter 14 Collapse

Objectives Explain the role of situational awareness in collapse. Identify the indicators used to anticipate collapse. Identify the various types of collapse. Apply risk analysis to fireground safety.

Objectives Identify the specific basic competencies all fire fighters should have to perform at a structural collapse. Explain the essential elements of the collapse of the World Trade Center twin towers on September 11, 2001.

Collapse: The Greatest Threat on the Fireground How fire fighters die Heart attacks (the greatest killer today) Smoke inhalation Falls Building collapse

Situational Awareness The perception of the surroundings in terms of time and space The understanding and comprehension of these observations The projected outcome of a change in these conditions

Communication Essential for situational awareness Protocols for collapse warnings

Anticipating Collapse Rely on training and experience. Use indicators and known precipitators.

General Visual Indicators of Collapse Cracks in walls Leaning walls Pitched or sagging floors © monbibi/ShutterStock, Inc.

General Visual Indicators of Collapse “Racked” doorways Presence of building stabilization and bracing features Courtesy of Glenn Corbett.

Audible and Physical Indicators of Collapse Moaning/groaning sounds Cracking noises Any type of movement Movement/shifting of water on floor

Audible and Physical Indicators of Collapse Smoke pushing through cracks in the wall Vibrations Lack of water runoff from firefighting operations

Environmental Precipitators of Collapse Heavy snow or rain load on roof Heavy wind collections Earthquake Impact load

Occupancy Precipitators of Collapse Overloading of floors and/or roof Concentrated loads Water-logged goods

Existing Structural Instability Precipitators of Collapse Structural compromises of load-bearing members during renovations Previous fire damage Rotting or corrosion of structural members from water leaks/damage

Existing Structural Instability Precipitators of Collapse Compromised/broken structural elements Eccentrically loaded columns Buildings under renovation/construction and buildings being moved

Fire and Explosion Damage Precipitators of Collapse Sustained moderate to heavy fire conditions Explosion Loss of wood structural mass due to fire attack

Lightweight Construction Precipitators of Collapse Unprotected, bare steel members subjected to fire Wooden I-beams and lightweight wood trusses subjected to fire Courtesy of Green Maltese, http://greenmaltese.com/.

Risk Analysis After fire fatalities Questions are asked Were fatalities caused by antiquated macho attitude? Taxpayers are saddled with unnecessary expenses.

Risk Analysis Professional fire services Analyze the relationship between risk incurred and benefits obtained Are well informed about construction features of buildings that have been available for study for many years

Types of Collapse Global collapse Partial collapse © Photos.com.

Types of Collapse Progressive collapse Secondary collapse Courtesy of FEMA.

Types of Collapse Pancake collapse

Types of Collapse Lean-to-floor collapse

Types of Collapse V-shaped floor collapse

Types of Collapse Cantilever floor collapse A-frame floor collapse Inward outward collapse

Types of Collapse 90-degree wall collapse Lean over collapse Curtain wall collapse Courtesy of Glenn Corbett.

Establishing Collapse Zones Fire fighters and fire apparatus must be kept out of collapse zones. Untrue: “Staying back one third the height of the wall is safe.” Fire fighters must remain at least the full height of the wall away. © Beth Keiser/AP Images.

Minimum Collapse Competencies for Fire Fighters Identified by NFPA 1670: Standard on Operations and Training for Technical Search and Rescue Incidents Higher competency levels require higher training.

World Trade Center: Our Worst Collapse Tragedy History of the World Trade Center Two of the tallest and largest buildings ever built Each tower was 110 stories high and each floor was 40,000 square feet. Each side of the building measured 210 feet in length.

World Trade Center: Major Structural Components Exterior walls A series of columns in the center core Lightweight steel floor trusses forming a composite floor Hat truss

World Trade Center: Mechanism of Collapse Studied by the National Institute of Standards and Technology (NIST) Used visual evidence of the exterior damage and computer modeling

World Trade Center: North Tower (Tower 1) Structural damage from the planes Jet fuel and dislodged fireproofing Open paths for fire spread Weakened core columns Sagging of the “south floors” Bowed south perimeter columns

World Trade Center: South Tower (Tower 2) Damage to the center core columns Jet fuel and dislodged fireproofing Sustained fires had an ample air supply Weakened core columns Sagging of the “east floors” Bowed east perimeter columns

World Trade Center: Questions About Incident How many trusses were destroyed in the initial impact? How many failed in the subsequent fires? How much fireproofing was knocked off by the plane impact? How many center core columns were damaged and destroyed?

World Trade Center: Questions for the Future Should lightweight trusses be used in high-rises? Should spray-on fireproofing come under more scrutiny? What role should fire services have in construction and regulation?

World Trade Center: In the End Be proactive in securing your safety and the safety of others. Get involved in the construction of a new building. Get involved in the code development and adoption process.

Summary All fire fighters have the responsibility to know the conditions for collapse in different types of buildings. Fire fighters and fire apparatus should be kept out of collapse zones.