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What are the different occupancies of buildings?
- A - assembly
- B - institutional
- C - residential
- D - business & personal service
- E - mercantile/commercial
- F - industrial
What are the two different types of loads?
Dead and live
Name 5 other factors dealing with loads
Wind, static, impact, repeated, and concentrated
Describe wind load
Forces applied to a building or structural member by the wind
Describe static load
Loads that are applied slowly and remain nearly constant (filling of a water tank)
Describe impact load
Loads delivered in a short time with a striking/collision effect
Describe repeated load
Loads applied intermittently (rolling bridge crane)
Describe concentrated load
Loads applied over a small contact area
What are the three ways in which loads can be applied?
Axial, eccentric, and torsional
Describe an axial load
Applied to the centre of the cross section of a structural member and perpendicular to that cross section.
Describe eccentric load
Applied perpendicular to the cross section of the structural member but is offset from centre, tends to bend the member
Describe torsional load
Offset from the centre of the cross section and at an angle to or in the same plane as the section, tends to twist the member
What are the 3 effects of loads on materials?
Compression, tension, and shearing.
Force that is crushing or pushing the mass of the material together
Force that tends to pull the material apart
Force that tends to cause adjacent planes in a structural member to slide past one another.
What is a fire load?
The maximum heat that can be produced if all the combustible materials in a given area burn
What is fire resistance?
The ability of a structural assembly to maintain its load-bearing ability under fire conditions. For walls, partitions, ceilings, etc. it also means the ability of the assembly to act as a fire barrier
What are the key factors that affect combustibility of building materials?
- Thermal conductivity
- Decrease of strength at elevated temperatures
- Thermal expansion when heated
What are the 5 types of construction
- Type I: fire-resistive
- Type II: noncombustible
- Type III: ordinary
- Type IV: heavy timber
- Type V: wood frame
Describe balloon frame construction
- Studs are continuous from foundation to roof
- Floor joists are nailed into the studs without a header
- Creates the potential for collapse
- Basement fires can spread up walls into the attic
Describe platform construction
- Each floor is built as a separate section
- The studs are only as high as the ceiling on each floor
- Header creates a fire stop
What are the 3 primary types of roof?
Flat, pitched, and curved
Name the indicators of roof collapse
- Cracking noises
- Extensive fire involvement
- Fire that has burned for a prolonged period
How far will a 100 foot steel beam/truss elongate when heated to 1000 degrees Fahrenheit/538 degrees Celsius?
What is the temperature when failure of steel can be anticipated?
1000 degrees Fahrenheit/538 degrees Celsius
What are 4 hazards of truss construction?
- Have no fat
- Failure of any element of the truss can cause the entire truss to fail
- Tying of adjacent trusses together to resist wind load may cause successive truss failure
- Carbon monoxide may accumulate in the voids and could cause a backdraft
Under fire conditions, failure of lightweight metal and wood trusses can be expected when?
After 5 to 10 minutes of fire exposure
What are load-bearing walls?
Walls which carry a load or some part of the structure in addition to the weight of the wall itself
What are non load-bearing walls?
Walls which support only their own weight
How big is a building collapse zone?
1.5 times the building's height
What are possible indicators of a building collapse?
- Cracks/separations in walls, floors, ceiling, or roof structures
- Evidence of existing structural instability (presence of tie rods and stars that hold the wall together)
- Loose bricks, blocks or stones falling from the building
- Deteriorated mortar between masonry
- Leaning walls
- Distorted structural members
- Fires beneath floors that support heavy machinery or other extreme weight loads
- Prolonged fire exposure to structural members
- Unusual cracks/creaking noises
- Structural members pulling away from the wall
- Excessive building contents weight
What are the 4 types of collapse?
V-type, lean-to, pancake, and cantilever
What are the two types of highrise construction?
Centre core or pigeon hole
Describe a centre core high rise building
- Floors are constructed around central core which contains stairwells, elevators, utilities, etc.
- Floors may be laid out completely different on one floor to the next depending on occupancy
- Generally constructed of metal
Describe a pigeon hole high rise building
- Constructed in a uniform fashion
- Each floor is identical to the floor above/below
- Generally constructed of concrete and generally house apartments
What is a high rise building?
- Beyond the reach of fire department aerial equipment
- Fires on upper floors must be fought from inside the building
- Poses the potential for significant "stack effect"
- Requires unreasonable evacuation time
What are the two different types of stairs?
Scissors and return
How does smoke spread vertically?
- Open stair shafts, elevator shafts, AC systems are the main channels that carry smoke
- Voids created by poke-through construction are often not sealed which can allow for smoke spread
How does smoke spread horizontally?
Hallways, ducts, concealed spaces, and AC systems
How do HVAC systems affect smoke spread?
- HVAC systems can suck smoke in and push it through to different areas of a building
- In the summer, AC can cool smoke which prevents it from rising as it normally would
What is mushrooming?
- The condition where heated gases expand and rise, reaching the top of a building and banking down to fill floor after floor with smoke and hot gases
- If the fire is not vented the heat will continue to build up until combustibles remote from the fire can ignite
What is stack effect?
The creation of layers of smoke and fire gases on floors below the top floors of unvented multi-storey buildings.