Collapse Of Burning Building Flashcards
NFPA leading cause of firefighter deaths
Stress Responding in returning to fires in emergencies Falls Falling objects Coming into contact with objects Firefighters caught and trapped Burning building collapse
Four factors that increase burning building collapse
Age of building, abandonment, lightweight construction materials, faulty renovations
Unprotected lightweight steel bar joist
They fail when exposed to five or ten minutes of fire exposure
What is the most common falling object at a structure fire
Broken glass from Windows being vented
The study of building collapse shows that
Number 1 floor collapse
Number-2 roof collapse
Number 3 wall collapse
Number 4 ceiling collapse
Balloon Construction
Exterior walls have studs extending continuously from the structures Foundation sale to the top plate near the Attic concealed spaces within those studs creates fire smoke and heat from the Selma area to the Attic
Beam definition
A beam is a horizontal structural member subject to compression tension and Shear supported by one of three methods
Cantalever beam support anchored only at 1 end
Continuous beam support beam supported at both ends in at the centre greatest structural stability of the 3
Simple supported beam a beam supported at both ends But not the centre
Braced frame Construction
Vertical Timbers call Post reinforce each of the four corners and horizontal Timbers called Gertz reinforce each floor Fasteners called mortise and Tenon joints connect them
During the fire this type of building will often fail and an inward outward collapse
Buttress
Wall reinforcement of a brace built on the outside of a structure sometimes called a wall column on a masonry wall a buttress is a column of Bricks Built into the wall
A buttress constructed on the inside of a wall is called a pilaster
Types of collapses
Curtain fall wall collapse- Exterior masonry walls drop like a fallen curtain cut loose at the top
Inward outward collapse -the wall breaks apart horizontally the top collapses inward the bottom collapses outward onto the street would brace frame constructions collapse in this manner
Other type lean over collapse, lean-to floor collapse, 90 degree angle wall collapse 10th floor collapse, the shaped floor collapse
Coping Stone
Top masonry tile or stone of a parapet wall designs Cary offering water weighs between 5 and 50 pounds
Corbel
Bracket for extension of masonry that projects from the masonry wall he can be a decorative ornament on the top of a parapet front wall or it could be used on the inside of a brick wall is it support for a roof beam end
Facade
Front face of a building hey Marky, cornice, canopy and parapet wall that extends above the roof level
An ornamental facade parapet wall with a Decorative Stone corbel coping is one of the most unstable walls a firefighter will encounter
Gusset plate
1/4 inch thick piece of sheet metal used to fasten lightweight wood trusses the points are 1/2 inch long that act as nails
Hierarchy of building elements as far as collapse
From least to greatest seriousness of collapse
- Deck. Less
- Beams ,floor,and roof
- Girder
- Column
- Bearing wall. Great
Interstitial space
I could seal space between floors used to contain large mechanical and electrical equipment the space can be up to eight feet high I contain a walkway for Access for maintenance
Kips
One kip equals 1000 pounds
Lintel
A horizontal piece of Timber stone or steel piece over an opening in a wall the lentil is a load-bearing structural element redistributes the load above the opening
Loads
AXIAL LOAD-passes through the center of a structure and is the most efficient manner by which and load can be transmitted to a structural support
ECCENTRIC LOAD- load transmitted off center or unevenly through a structural member
Lateral load applied to an upright structure from a direction parallel to the ground example ladders
Torsional load and load that creates a twisting stress on a structural member when a large steel girder collapses at one end the other end experiences a torsion or twisting stress
Load stress
Internal stress created by a load in a structural element including compression stress tension stress and shear stress a collapsed can a crow run a stress created by a load of Si Tu Lo Karen capacity the structural element
Collapse by compression stress is the failure of a steel column we can buy the heat of combustion
1 of Collapse by tension stress is the failure of fire weaken steel or wood hanger straps holding up a suspended ceiling
One of Collapse by shear stress is a collapse of a brick veneer wall breaking away from the cement bonding in falling in a curtain fall collapse
Open web steel bar joist
unprotected open web steel bar joist can collapse after 5 to 10 minutes of fire exposure
Pilaster
A masonry column Bond it too and built as an integral part of the inside of a masonry wall a pilaster can carry the load of a girder or Timber or it can be designed to provide lateral support to a wall
Purlins
A Timber late horizontally perpendicular to support the common rafters of a roof
Safety Factor
The quotient of the load that will cause a structure to collapse divided by the load a structure is designed to support
Most structural elements are designed with a safety factor of 2 or more
Truss roof beam collapse
Spaced farther apart then solid beams a lot of unsupported roof deck
The failure of one timber truss space 20 feet apart supported 100 by 100 foot roof can collapse 4000 square feet of roof
Fire resistive Construction
The major problem in a fire resistive building is the central air conditioning system every fire barrier in the building is penetrated because of the large system
An Air Supply Ducks penetrate a fire resistive wall and automatically closing shutter is designed to close the air inside the duck reaches a specific temperature the heat activated fire damper me stop Flames red but not stem the spread of smoke throughout the systems are ducks which is dangerous because three-quarters of all fire deaths United States are caused by smoke not playing
Type 2 non-combustible limited combustible Construction
The fire problem associated with this type of structure is the flat combustible asphalt roof deck covering that can ignite during a fire operations
Multiple layers of hot asphalt is mopped over the entire roof area combustible felt is placed over the roof also
The total weight of asphalt used between the steel deck in the insulation should not exceed 12 to 15 pounds per square feet of roof area
Type 3 ordinary construction brick in Wood joist
The major problem in an ordinary constructed building is the fire and smoke spread throughout concealed spaces. The voids contain combustible material like wooden, lath
The largest and most serious concealed space is the common roof space or cock loft the space above the ceiling in below the roof
Heavy Timber
For building to qualify as heavy Timber Construction wood columns cannot be less than 8 in thick in any dimension in the wood girder cannot be less than 6 in thick
The major problem of the brick enclosed Timber structure is the large wooden interior timber frame work
Advantage of not enclosing ceilings or Timber and plaster are that there are no concealed spaces no obstructions to the firefighters hose stream and no hidden Flames behind ceilings or walls
Type 5 wood frame Construction only one of the five that has combustible exterior walls
Wood frame construction has seven sides above the fire below the fire in the four sides of the fire the seventh side must be considered the combustible exterior wall
Type 1 Fire resistive construction collapse hazard
Two types of fire resistive construction’s reinforced concrete buildings, structural steel buildings
Fire resistant buildings are the most stable but the collapse danger lies in the concrete
In reinforced concrete buildings heated concrete ceilings collapse on top of firefighters caused by spoiling the rapid expansion of heated moisture inside the concrete the pressure can cause heavy sections of concrete to crack away from the ceiling in collapse down
Structural steel built buildings the concrete is on fluted deck so when the deck is heated the concrete explodes the floor upward
Type 2 non combustible limited combustible Construction collapse hazards
The collapse danger to a firefighter from a non combustible building his roof cave-in the collapsing material and the unprotected steel open web bar joist
The open web bar joist is the main structural Hazard of non-combustible construction
Type 3 ordinary Construction collapse hazards
Has exterior bearing walls a masonry with wood floors in roof call Brick and joist
The structural has it of an ordinary constructed building is the parapet wall the portion of masonry wall that extends above the roof
The slightest lateral force will topple the bricks over into the street or back on the roof
Type 4 heavy Timber Construction Collapse hazard
Follow me sneer walls that crashed to the ground is break bahnsen chunks of bricks and mortar along the street or pavement are the structural hazards of heavy timber buildings
Withdrawal to protect exposures is a strategy used at a fire a heavy Timber construction when the initial attack fails
Type 5 wood frame Construction
The truck show Hazard of a wood frame building is the combustible bearing walls constructed of 2 by 4 inch wood studs
Failure of a bearing wall will trigger simultaneous failure of the floors and roof
Types of masonry wall collapse
A 90° angle collapse is the most common type of masonry wall failure that occurs at fires the Walthall Street out and the top of the collapse of wall strikes the ground a distance equal to the height of the Fallen section measured from the base of the wall
Masonry walls
Separate from the other enclosing walls at Corners where they intersect if there’s no brick bonding of the intersecting walls but either overlapping brick bonding or metal reinforcing rods the wall May split apart at this point
Inward outward collapse
An example of an inward outward collapse is a masonry wall failure caused by the collapse of a bowstring Timber truss roof
Parapet walls
Are unstable because they are freestanding a freestanding wall is considered by Engineers to be the least stable of three basic types of walls because there’s fewer connection
A parapet wall is a vertical cantilever beam a cantilever beam is supported at only one end
Marquee
And Marquee is a cantilever beam supported at only one end that is connected to the parapet wall
Another cause of Marquee collapse is overloading due to water buildup inside the Marquis
Canopy
The canopy is more of a collapsed danger than a marquis canopy is a cantilever beam like a marquis but it is lightweight and constructed of small pieces of wood or metal held together by bolts cables and small pieces of framework
The Marquee is one large continuous beam supported only at one end
The most dangerous type of canopy is a metal or wood shed suspended over a truck loading area
A cornice
Is a decorative horizontal overhang projected outward along the top wall of a building the corners can be defined as a portion of the roof extending out Beyond and exterior wall Corners is also a cantilever structure
Parapet wall collapse
Masonry parapet wall is one of the most dangerous walls that a firefighter can encounter at a fire
Because of the hazards of falling objects that most dangerous area outside of a burning structure is the sidewalk directly in front of the building
The most dangerous pure pit however is the one constructed as the front wall of a one-story structure above several large display Windows the sort found in supermarkets shopping malls in rows of stores this type of wall is also free standing
Parapet wall that is susceptible to Total collapse during fire fighting operation
Ornamental cast stone in decorative terracotta parapet walls are often attached to Steel reinforcement rod in angle iron making them the most susceptible
Parapet wall collapse facts
Firefighters must estimate the horizontal as well as the vertical collapse danger zone
Collapse of a parapet wall Dangers
Parapet walls often collapse during the OVERHAULING stage of a fire after the structure has been weakened and partially destroyed by fire in large calibre master streams
Ordinary masonry fact for collapse
Distance from the wall equal to 1 1/2 or twice its full height and bricks may bounce or roll further
Floor collapse
Floor failure is the leading cause of firefighter death by collapse