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?
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
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
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.