Lec 12 Flashcards
Explain iron and steel for steel reinforcement
- steel is a refined product of iron ore
- iron oxidizes very easily
- natural deposits of iron ore contain high percentages of oxides
- to separate the oxides: starts with blast-furnace and followed by the open-hearth or electric furnace
https://ibb.co/xLcJhks
What does the blast furnace process do?
reduces the ore to pig iron and has slag as a byproduct
what percentage of carbon is too high to permit its use as a construction material subjected to tension?
3,5 to 4,25 %
Cast iron is brittle because of high percentage of carbon.
specific things about iron (used for?, effects, amount)
- used to make steel sheets, steel bars, angle steel, wide-wing beams, large structures, screws, bolts, bearing, building structures, etc
- the higher the carbon content -> greater the hardness -> more brittle
- carbon content in iron is <= 0,025%
- carbon content in steel is 0,025% to 1,5%
- carbon content in cast iron is > 2%
classification and manufacturing of iron
https://ibb.co/R7N6ZyR
3 types of steel
- low-carbon steel (mild steel): carbon content (0,15-0,20%) -> soft and has significant ductility -> easy to form -> suitable for construction projects
- medium-carbon steel: used in machine parts and the main use is for concrete’s steel reinforcement -> carbon contents > 0,35%
- high-carbon steel: tool steel -> kek buat pisau, dll
Properties of steel
- change depending on the carbon content
- carbon content high -> INCREASE: hardness, strength, abrasion resistance -> DECREASE: ductility, toughness, and impact resistance
https://ibb.co/D7nnGmy
Mechanical properties of steel
- modulus of elasticity = 2,04 * 10^6 kgf/cm3
- temperature affects
- Thermal processing is at a temperature slightly higher than the transition temperature (range 500
-1200 ℃). This processing can refine the structure and promote the melting of bubbles to form a uniform material - cold working -> material fibrous -> increase tensile strength, yield strength, and hardness and reduce elongation and ductility
https://ibb.co/pf4gmGp
Explain construction steel shapes
https://ibb.co/cbf1c89
- structural section steel refers to the section steel with flanges rolled from steel billets or ingots (various shapes and grades)
- W-shaped steel is most widely used, as a beam or column member
- I (S) shape steel is a double symmetrical steel with slope is approximately 16,7 degrees. its flange with is < than W-shaped
- the inside surface of C-shaped steel is the same as I-shaped steel (16,7 degrees)
- L-shaped steel is equilateral or unequal side
Structural steel models codes
https://ibb.co/FmDJrVs
- represented by a single letter and
two numbers separated by multiplication signs - For example, W8 × 67, where the letter (W) is the identification type, the first number (8) is the nominal depth of the section in inches, and the second number (67) is the length per foot Weight (lb/ft).
- higher depth -> higher bending capacity
- I = bh^3/12
Types of construction steel
https://ibb.co/J5GwYwg
- yield strength increasing -> brittle -> not strong
what is RC (type of steel reinforcement)
The combined use of reinforcement and concrete as a composite material to bear compressive stress and the reinforcement -> receive tensile stress -> increase the bearing capacity of the beam by dozens of times
what happens in long-span beams or columns in term of compression reinforcement
compression reinforcement is usually deployed to reduce the cross-section and increase the use of space
what does the roughness and deformation of the surface of the steel bar do
enhance the grip between it and concrete
Type of reinforcement
1) plain bars
2) deformed bars
3) wire fabric
