Materials Concrete and Steel Flashcards
What is hot rolled steel, and where is it typically used?
Hot rolled steel is formed while molten and is typically used in heavy structural applications. It’s used in commercial buildings and some residential buildings for heavy loads or large spans.
How is cold-formed steel made, and what is its common use?
Cold-formed steel is made by guiding thin sheets of steel through rollers to shape them. It’s commonly used for corrugated roofing, wall and ceiling framing (e.g., Rondo), and is often connected by screws, rivets, or welding.
What are UC (Universal Columns) used for in structural steel design?
UC (Universal Columns) are commonly used for vertical load-bearing applications, such as supporting heavy loads in buildings.
What is the difference between a UC (Universal Column) and a UB (Universal Beam)?
A UB (Universal Beam) is similar to a UC but is wider in relation to its height. It has wider flanges and is designed to bear loads primarily in bending, while a UC is mainly used for vertical load-bearing.
What is galvanization in steel, and why is it used?
Galvanization involves coating steel with a layer of zinc to protect it from corrosion by allowing the zinc to corrode instead of the steel, thus extending the steel’s lifespan.
What are the different methods used to join steel components?
Steel can be joined using bolts, welding, or connectors (such as for corrugated steel), and anchors (e.g., bolts or concrete nails) to connect steel to concrete slabs.
What are the health and safety precautions when handling concrete?
Protective clothing (gloves, goggles, long sleeves), correct lifting techniques, and working in well-ventilated areas are essential.
What is the mix ratio for general purpose concrete?
1:2:3:0.5 — 1 part cement, 2 parts sand, 3 parts gravel, and 0.5 part water.
What is the purpose of set retardants in concrete?
Set retardants are added to delay the setting time of concrete, allowing for longer workability, especially in hot climates.
What is the strength rating of high strength concrete?
High strength concrete has a strength rating of 35 MPa and above.
What are construction joints used for in concrete?
Construction joints form where two separate placements of concrete meet, providing a physical separation between different pours.
What is the difference between pre-tensioning and post-tensioning in concrete?
Pre-tensioning involves tensioning steel tendons before pouring concrete, while post-tensioning involves placing tendons in ducts before curing and then tensioning after curing.
What is the purpose of isolation joints in concrete?
Isolation joints separate concrete slabs from adjacent structures, allowing independent movement of different sections.
What are the principles of water penetration in buildings, and how are they managed?
The 4Ds of weathertightness are Deflection (redirecting water), Drainage (removing water), Drying (allowing moisture to evaporate), and Durability (ensuring long-lasting materials).
How does capillary action affect building materials?
Capillary action occurs when water moves through small gaps by surface tension, potentially causing water to cling to surfaces. Gaps larger than 1mm break this action.
What is the impact of air pressure differentials on water penetration?
Air pressure differentials, like wind pressure, can force water through gaps, causing drafts and water infiltration into the building.
What is the significance of thermal mass in building materials?
Thermal mass refers to a material’s ability to absorb, store, and later release heat, helping to maintain stable indoor temperatures.
What are the main types of heat transfer?
Conduction (through direct contact), Convection (through air movement), and Radiation (through electromagnetic waves).
How can condensation in buildings be prevented?
Use double or triple glazing for windows, proper insulation for steel and aluminum, and ensure good ventilation.
What is sound transmission class (STC), and how does it relate to building materials?
STC measures a material’s ability to block airborne sound. Higher STC ratings (above 55) indicate better sound insulation.
What is the difference between low and high-frequency sounds?
Low-frequency sounds (below 100Hz) travel long distances and are harder to block. High-frequency sounds (above 2000Hz) are easier to block using soft materials.
How is deflection managed in structural elements like beams or columns?
Deflection (bending or displacement) is minimized by designing beams with adequate depth, using tensioned steel strands, and incorporating proper hardware.
What are the common methods for dealing with poor ground conditions in NZ construction?
Common methods include reinforced concrete slabs on hardfill or using piles (steel, timber, or concrete) installed at suitable depths to ensure structural stability.
What are the two main types of insulation materials used in buildings?
Polystyrene (underfloor insulation) and fibrous materials such as wool batts or foam insulation for walls and ceilings.
