Chapter 14: Building Construction
Terms in this set (61)
What are the five types of building construction?
Type 1 - Fire resistive construction
Type 2 - Noncombustible or limited combustible construction
Type 3 - Ordinary construction
Type 4 - Heavy Timber construction
Type 5 - Wood frame construction
What are the qualities of Type 1 - Fire resistive construction?
-Fire resistance provides structural integrity during a fire.
-Has structural members including walls, columns, beams, floors, and roofs made of noncombustible or limited combustible materials with sufficient fire-resistive ratings that allow those components to withstand the effects of fire and also prevent its spread from floor to floor
Eg: steel sprayed with fire protection coatings, steel encased in concrete, or monolithic-poured concrete
Because of the limited combustibility of the material of construction, what are the primary fire hazards of Type 1 - Fire resistive construction?
The contents of the structure
What are some examples of Type 1 - Fire resistive construction?
World Trade Center
Poundmaker training facility
Jubilee Auditorium's and many other outdoor parkades
Many hi-rise commercial office buildings with fire protected metal steel components and/or concrete roofs
What are the qualities of Type 2 - Non combustible or Limited combustible construction?
-Similar to Type 1 construction except the degree of fire resistance is lower
-Materials with no fire ratings such as untreated wood may be used in limited quantities
-The heat building from a fire in the building can cause the structural supports to fail as they do not have the fire protection coating applied as in Type 1
-Often have flat, built-up roofs that contain combustible felt, insulation, and roofing tar.
What are the primary fire hazards of Type 2 - Non combustible or limited combustible construction?
The contents of the building
What are some examples of Type 2 - non combustible or limited combustible construction?
Training school and Fleet Services building
McNally Composite high school and many/most of the others
Most of the fire halls across the city
Most larger shopping malls
Grand Trunk arena and many alike, etc
What are the qualities of Type 3 - Ordinary construction?
-Ordinary construction features exterior walls and structural members constructed on noncombustible or limited combustible materials
-Interior structural members including walls, columns, beams, floors and roofs are completely or partially constructed of wood.
What is a fire cut, and why does it exist?
-A 30 degree (roughly) diagonal cut from top to bottom on each end of the solid beam joist made with the longer end of the joist placed deep into a pocket in the wall
-In the event of a floor collapse, the cut would allow for the joist to fall without creating any pressure and potentially collapsing the exterior wall
What is the primary concern specific to Ordinary construction?
The problem of fire and smoke spreading through concealed spaces. These spaces are between the walls, floors, and ceilings.
What are some examples of type 3 - Ordinary construction?
-Flat iron building (Jasper and 96th street)
-Many buildings buildings in the downtown core that have been refurbished into lofts allowing for residential occupancy
-Strip malls with cinder block walls and wood truss roofs
What are the qualities of Type 4 - Heavy Timber (Mill) construction?
-Features exterior walls made of noncombustible materials
-Interior components include large beams, columns, arches that are made of solid or laminated wood with no concealed spaces
-Roof and floor are typically plank board.
-Columns can not be less than eight inches thick in any dimension, and a wood girder cannot be less than six inches thick
What is the primary fire hazard associated with Type 4 - Heavy Timber construction?
the massive amount of combustible contents presented by the structural timbers in addition to the contents of the building
What is Post and Beam construction?
-Also called Tudor-style - has a partially exposed frame on the exterior of the building.
-The frame bears the structural load and consists of either 6x6 or 4x4 inch members. These must have diagonal bracing
-The joints are mortise and tenon, which serve to transfer the loads
-The actual walls between the frameworks are not structural or load-bearing.
What are some examples of type 4 - Heavy Timber construction?
Boardwalk (103rd street and 102nd avenue)
Many older warehouses
Hangars at the municipal airport
What are the qualities of Type 5 - Wood frame construction?
-Has exterior walls, bearing walls, floors, roofs, and supports made completely or partially of wood or other approved materials of smaller dimensions than those used for heavy timber construction.
-Commonly used to construct the typical single family residence
What is balloon frame construction?
Consists of 2x4 studs that may run two or more stories high.
The ribbon board supports the joists
Unobstructed channels run between the studs from the cellar to the attic, and between the joists from wall to wall
What is platform frame construction?
Has built in fire stops between each floor.
No continuous vertical spaces
Joists laid across on the main platform, then sub-flooring is laid on the joists.
Walls are then erected on the platform.
What does the strength of wood depend on?
Type and grade of wood
Direction of Load and grain
What are the factors that affect wood's ignition temperature and reaction to fire?
Density of wood
Size and form of wood
Rate of preheating
What can size and moisture content be altered by?
Smaller pieces of wood are less likely to burn and fail quickly than larger ones, T or F
Larger pieces of wood are less likely to burn and fail quickly than larger ones
Does water affect the structural strength of wood?
When applied to burning wood, water stops the charring process and minimizes damage
What is plywood, and how does it react in fire conditions?
Plywood is an engineered wood made from thin slices of wood laid at right angles to one another, and glued together
In fire conditions, plywood de-laminates and burns hot and fast, with dense smoke
What are spliced timbers, what is a very serious threat in fire conditions, and what should firefighters protect in regards to spliced timbers?
-Spliced Timbers are made from planks that are glued together under pressure and often bolted to produce large timbers.
-Collapse is a very serious threat in fire conditions; the steel connectors used to splice the beams often fail.
-It is very important that firefighters protect the splice with a water stream.
What are glue-lam beams
Glue-lam beams are wooden structural members composed of many relatively short pieces of lumber glued and laminated together under pressure to form a long, extremely strong beam
What are planks, and how do they react under fire conditions?
Planks are fabricated lengths of wood built by gluing three boards together. The centerboard juts out on one end and is recessed on the other.
In fire conditions, planks tend to separate and burn in much the same as plywood.
What is chipboard, and can it fail under water stream?
Wood chips are glued together to form a sheet of chipboard.
Some chipboard is water soluble, and can fail under water stream.
What does OSB stand for?
Oriented Strand Board
How is OSB made?
Strands, flakes, or wafers of small, round logs are bonded with and exterior-type binder under heat and pressure.
Where is particleboard used?
Commonly used in all types of building construction
What does MDF stand for and what are its advantages?
Medium Density Fiberboard
Ease of machining
Good weathering properties
The ability to be made from a wide variety of fibrous products
What are some problems that arise during firefighting operations when dealing with MDF?
When MDF made with formaldehyde resins burns, it will release irritating and toxic fumes and gasses including carbon monoxide, hydrogen cyanide, aldehydes, organic acids, and polynuclear aromatic compounds.
There may also be an explosion hazard when MDF is sawed, planed, or machined as a fine dust is produced.
What is often the LEL for wood dust?
40 grams of dust per cubic meter of air
Why are bricks, tiles, stones, and concrete masonry products commonly used in construction?
They are minimally affected by fire and heat
They are durable, easy-to-use, and long lasting
What is usually the weakest part of a masonry wall?
The mortar supporting the masonry.
More often than not, it is the fire suppression activities that causes damage to the masonry
What are the advantages to using Steel as a building material?
Resistant to aging
Easy to work with
Easy to connect to other building components
Made of ________ and ________ steel is prone to ________ when exposed to the elements and loses strength under _____ conditions?
a 30M steel beam can extend by as much as ____ cm when heated from room temperature to approximately _____ degrees C?
What is the rate at which unprotected steel fails dependent upon
The mass of the steel component
The intensity of the fire
The load carried by the steel
The connections that hold the steel members together
Where there is less mass, less heat is needed to cause steel failure
What will happen if unprotected steel is restrained from movement at the ends, and what can us as firefighters do to avoid structural collapse?
It will bend, buckle, and fail somewhere in the middle of the beam.
Apply water to cool the steel and reduce the risk of failure and subsequent structural collapse
Steel can be insulated or fireproofed with spray-on coatings, plaster, gypsum, fiberboard, or ceiling tile. Once exposed to fire conditions, however, insulated steel will behave like __________?
What often fails under fire conditions in buildings with cast iron construction?
the bolts and other connections that hold the cast iron to the structure.
Although cast iron stands up well to fire, it does not do was well under fire suppression conditions. The rapid cooling caused by water application causes cast iron to _________?
Crack and shatter
Concrete has strong ________ strength, but little _________ strength. As a result, it is most commonly used in foundations, columns, floors, walls and pavement
T or F, reinforced concrete stands up well to fire conditions?
What is the fire resistance rating range in gypsum?
one to four hours
Why should firefighters be alert when gypsum starts breaking down?
Gypsum is highly heat resistant due to its high water content.
When gypsum breaks down under intense heat and fire conditions, the steel and wood structural beams behind it will be subjected to extremely high temperatures, and as a result, may lose structural integrity
What is plaster?
A fire-resistive, cement-like material that is applied in several coats over a backing material of wire or gypsum board called lath to form a finished surface.
All glass is ____________ but it has little ________?
Wired glass and fire-rated glass have fire ratings of?
45 or 90 minutes
Why are plastics seldom used as structural members in building construction?
because of their tendency to bend and their lower rates of thermal conductivity
What is a Fire Load?
The amount of potential fuel available for a fire to burn
A combination of the combustible building contents and combustible building parts
What are Structural Loads and what are some examples?
Forces that work against a structure's ability to remain standing
Soil pressure against the side of a wall
What is a Dead Load and how is it related to the structural members of a building?
The weight of the building and any attached fixtures (eg: drywall, HVAC systems, plumbing, flooring)
The structural or load-bearing members of the building are designed to support and share this dead load.
What is a Live load, and how are buildings designed to accommodate live loads?
Any load on a structure, other than a dead load - includes building contents, occupants, and the weight of snow or rain on the roof.
Buildings are usually designed with a specific use in mind. When use changes, live loads change and the building may not be able to support the change in load, especially in fire conditions.
What are Impact loads?
Sudden, one-time, short-term bursts of pressure that can produce very high stresses, especially when applied laterally.
What are Static loads?
Gradual or constant pressures applied over the long term
What are Repeated loads?
Pressures applied intermittently over a period of time. (Wind is an important repeated load)
What are the Internal forces of a structure?
Compression loads - squeeze and shorten a member
Tensile loads - pull apart or lengthen a member
Shear loads - cause the planes of the member to slide past one another
Concentrated loads - are focused in one small area, rather than spread across the length of the structural member
What are the different stress loads on a structural member?