structural steel Flashcards
How much carbon does cast iron usually contain?
As much as it can hold = 4%
What is wrought iron?
iron that contains glassy inclusion and less that .08 % carbon.
What is steel?
Iron with generally less than 1% carbon in it.
What is pig iron?
Raw iron. usually 4-5% carbon, making it quite brittle. immediate product of smelting iron with coke and limestone in blast furnace.
What is the tensile strength of commercial mild steel?
60ksi
What is the tensile strength of cast iron?
10ksi - 40ksi and higher
What is the tensile strength of wrought iron?
20ksi - 40ksi
What defines a plate?
Sheet steel with width of more than 8” w/ thickness ranging from 1/4” or greater.
what are the 4 grades of PCC tensile strength?
40, 50, 60 & 75 KSI
How is rebar size indicated?
No. 4 rebar = 4/8 = 1/2” diameter
What does grade 60 mean for rebar?
Fy = 60,000 KSI
How to find are of rebar?
(barsize/9)^2
ie. #8 = (8/9)^2 = .79si
* Only applies to #8 or smaller.
How is welded wire reinforcement (WWR) sized?
6 x 12 - W12 x W5
Where: * 6 = longitudinal (length) spacing
* 12 = transverse (width) spacing
* W = smooth, D = deformed
* 12 & 5 = long & trans sizes (cross sectional area .12si & .05si)
What is required WWR placement?
Placed middle third of a 4”-6” slab, 2” below the surface is generally recommended.
Definition of structural design?
Determination of overall proportions and dimensions of the supporting framework and selection of individual members.
What is impact vs fatigue?
Impact are loads suddenly applied to the structure. Fatigue referes to loads applied and removed many times over the life of the structure.
Pros and cons to welding.vs bolting
Pros: No need for munching/drilling simplifies complicated joints Cons: greater skilled required more expensive weld inspection expensive
Pros and cons to bolting vs welding
Pros: Easy for job site installation cheaper Cons: Requires drilling/punching
Steel production process
1) reduction of iron or to pig iron
2) Refining pig iron to steel
3) reforming steel into products
Define these organizations
AISI: american iron and steel institute
SAE: Society of automotive engineers
ASTM: America society of testing materials
AISC: American institute of steel construction
ASHTO: American association of state and highway transportation officials.
materials used to produce pig iron.
- coal - as coke - used to supply carbon.
- Limestone - helps remove impurities
- Iron ore - processed ore at start produced about 65% iron
- Impurities (slag) float to top.
- about 3.2 tons of raw materials to produce 1 ton of steel.
Relationship B/W ductility and carbon
the more carbon, the less ductile.
Types of furnaces used to refine pig iron or steel scrap.
- Open Hearth (not used in us)
- Basic oxygen
- Electric arc
What are the salvageable rates of recycled steel for basic oxygen and electric arc furnaces?
Basic oxygen = 25-35%
Electric arc = 95-100%
3 types of ways to heat treat steel
1) Annealing
2) Normalizing
3) quenching
What is Annealing treatment?
alter physical properties of material to increase its ductility toughness and reduce hardness
What is Normalizing?
Higher strength than annealed steel. High strength and hardness. Used as corrective treatment.
What is quenching?
Cooling metal in liquid to make very hard form of steel crystalline structure (martensite). Stronger that ferrite due to high carbon content.
What properties are allow agents intended to serve?
- hardness
- corrosion resistance
- machineability
- ductility
- srength
Common allows for steel
Aluminum: removes oxyge
Chromium: Increases resistance to corrosion
Nickel: increase toughness
Copper: aids corrosion resistance
Manganese: Increases hardness
Silicon: improves toughness and hardness.
What is the yield strength of steel?
Stress where plastic elongation of material has commenced.
Yield point (upper yield strength)
stress at first 0 slope and the oneset of plastic deformation.
Lower yield strength
Minimum stress recorded during discontinus yielding.
