Chapter 2 Flashcards
5 factors that determine the suitability of a material
Type of material Shape Orientation or plane Mass Material surface, rough, smooth
Surface to mass as it relates to FFing
The more mass a material has relative to the exposed surface area, the more resistant to heat
When a material degrades it also__________. And a change in shape can cause a change in _________
Deforms
Load imposition
Most new buildings are_____________and __________
high strength
Low mass
Brittle
Ductile
Fracture as it is stressed-
Masonry, tile, cast iron
Bend deflect or stretch as a load is applied
Most metal, plastic and wood
4 basic building materials
Wood
Steel
Concrete
Masonry
All native woods are not the same, name 6 types
Hard Soft Tight grained Knotty Old growth New growth
How long before Pine and Spruce trees can be cut?
25 years
What is Pitch?
Found in trees, burns like a petroleum product.
New growth trees have more of it than old growth
Wood used to be cut from:
The heart of the tree which was denser and had less pitch
In what year and in what way did wood standards change?
1986, went from Utility, std, construction grade, and select to #3,#2, and #1 with 1 being the best
What type of wood used to be used for exterior? Interior?
Douglas Fir
White fir, Hemlock
Now the white fir is used on the eXterioir
What’s the difference between full dimensional and nominal dimension lumber?
1/2”,
Traditional wood products are primarily
Heavy timber
Glue-laminated beams and columns
Sheathing
Different from EWP
Glulams:
Made from smaller pieces, used to be strapped together, then glued. Glues are toxic
3 types of sheathing
Plywood-altering veneers at 90
Particle Board-pyrolizing flashover
Decorative sheathing-1/8- 3/8- does not support weight
What has replaced plywood?
OSB
Can you use Decorative wood sheathing for interior panels?
NO, not by code
EWP
Transform wood chips, slivers, veneers, shavings and even recycled products to make wood
New growth wood, cellulose, wheat, straw, lots of pitch and loose grained
EWP process
Processed, milled, emulsified (add adhesives, and then auto claved( heat and pressure) into shape
6 types of EWP
OSB LVL-laminated veneer lumber LSL-strand CLT-Cross lam timber GLT-Glue Lam timber Finger jointed
OSB, describe
Urea-formaldehyde Degrades in sunlight, moisture and heat Randomly oriented layers Will ignite and burn rapidly Roof and floor assemblies
LVL
Phenolic Resin
Native wood stacked with aligned grains
Designed to have load imposed axial lay and perpendicular to the grain
Beams, joists, rafters, columns, studs, rim boards
LSL-Lam strand or PSL, parallel strand lumber
Urea, phenolic resin or phenol formaldehyde
Uses strands oriented in a parallel fashion
Used like LVL, but fails sooner
CLT-cross lam
3-7 layers Rotated 90 degrees Structurally sound form of plywood, but thicker Eco for sound and carbon foot print Used for columns
How is CLT a green product
Per 1 ton of wood, it takes 5 times more energy to make concrete,
24 times for steel, and
126 times for aluminum
GLT-Glulam Timber
Similar to Glulam
Loved by designers for the shapes it can make
Uses pieces of timber
Columns and beams
Finger jointed, FJL
Using native wood,
Mitered, pressed and glued to make long pieces of lumber
Can make 90 degree pieces!
4 types of adhesives used in EWP
Urea form
Phenol form
Melamine form
Methylene diphenyl diisocyanate -expensive
Steel is made from
Iron ore, carbon and an alloy agent
3 ways steel is formed
Casting, hot rolled or cold rolled…Rick rolled
Hot rolled steel - extruded
Shaped at temps above the crystallization stage
Thinner sheets and shapes
Cold rolled steel
Shaped as it cools Below crystallization temps Stronger than hot rolled Cut or rolled steel Nuts, bolts, wires, rebar
Two weaknesses of steel from a fire service view
Engineered for specific applications
Softens and elongates when heated
Strength of steel
Resists, compression, tension and shear forces
Cold rolled steel loses its strength at:
Hot rolled steel:
55% at 800
50% at 1100
And it can elongate at 1000 degrees, 10”/100ft
Cast iron
Brittle Good compressive Ok shear strength Used to be used structurally, Can resist slow heating and cooling, but might explode if cooled too quickly in a fire
Aluminum
Most abundant Soft Height strength/weight Ductile Non corrosive and non magnetic
Why does aluminum fail in a fire?
Low mass and ductile nature
Titanium
Similar to Aluminum
Exception to the lightweight view of early failure
Expensive
What makes up concrete
Portland cement, sand, and aggregate
Low slump concrete is
Stronger
Lower water to cement ratio
High slump concrete
Is weaker
Wetter
Flows easier
Cured concrete has excellent___________, but poor__ and _____
Compressive strength
Shear and tensile
Reinforced concrete
Poured over rebar, becomes part of cured mass
Pre- and post tensioned concrete
Has steel cables through the plane of the material, compressing the concrete
Precast concrete
Slabs, tilt up, roof, walls and floors
Monolithic buildings
Concrete built with wood forms
One floor at a time
Floors are built on scaffold like platform called false work
Unlike steel, concrete is a _____ ________and tends to slowly_________and _________heat. Steel _______ heat
Heat sink
Absorb and retain
Conducts
Spalling
Caused by moisture in the concrete that when heated can cause cracking, cracking can expose rebar which will conduct heat and cause major failure
How can concrete buildings be a hazard after a fire to FF?
Retain heat, making it strenuous to do overhaul
Masonry terms
CMU-
Veneer wall-
CMU- concrete masonry unit
Veneer wall- only supports its own weight
Mortar is made of
And
Sand, cement, and lime, and water
Has little to no tensile or shear strength
As axial loads and compressive forces increase
Masonry walls get stronger
Composites
Designed to offer maximum strength with minimal mass
Plastics def:
Synthetic or semisynthetic material this is made of mold able polymers
Derived from petroleum
Plastic can be divided into 2 groups
Thermo plastics- can be reheated and reshape do
Thermosetting plastics-use heat to form so reheating will breakdown
Industry is the _____leading consumer of plastics
2nd
Plastic characteristics
Melts at low temps and emits very explosive gases
Carbon Fiber reinforced polymer CFRP
Strong
Expensive-not used
Initially strong until fibers are exposed to flame
Release microscopic carbon particles that can burn
Fucks up circuits
