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Questions and Answers
What are the two main types of bolts mentioned in the fabrication process?
Ordinary bolts and high strength friction grip bolts.
Why is shop welding preferred over site welding?
Shop welding is preferred for better quality control.
What are the key tasks to be performed during the erection phase?
Secure crane information, check transport of member lengths, and decide laydown area.
What factors should be considered when selecting a crane for construction?
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What is the importance of inspecting welds visually during fabrication?
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What is the primary purpose of using deep-piled foundations?
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List two types of displacement-driven piles mentioned.
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What are the advantages of using timber for driven piles?
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What is a key feature of precast concrete piles when they are prestressed?
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Why is splicing not desirable for precast concrete piles?
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Identify one type of cast-in-place pile.
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What type of section is used in closed-ended steel tube piles?
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What characteristic of bulb piles distinguishes them from other pile types?
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What is a key requirement for the temporary wire rope guys during steel erection?
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In Option 2, what is the significance of crane positioning?
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What are the advantages of Option 1, assembling in place, despite being time-consuming?
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Why is the crane location not critical in Option 1 for steel erection?
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Describe what the existing steelwork's role is during the erection of new steel structures.
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What does the term 'plumbing radius' refer to in the context of steel erection?
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What is the purpose of the temporary support towers in the construction process?
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What phase comes after erecting enough steelwork in Option 1?
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What is the purpose of cutting wires once concrete has cured?
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Describe the role of tendons in post-tensioning concrete.
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What are the two main types of construction regarding the filling of ducts after stressing tendons?
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What equipment is typically used to apply tension to the rods in post-tensioning?
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Why are duct tubes installed in concrete blocks before curing?
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What is the function of anchorage blocks in post-tensioning?
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What is one advantage of using unbonded post-tensioning?
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Identify one potential component used in the reinforcement of concrete blocks during post-tensioning.
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What is the main difference in the placement of cables between pre-tensioning and post-tensioning methods?
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How does the bonding of concrete to cables differ in pre-tensioning compared to post-tensioning?
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What action is taken after the concrete hardens in the post-tensioning process?
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What measures are taken to maintain the stress in post-tensioning?
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What is done to the ducts after the post-tensioning cables are stressed?
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Study Notes
Deep-Piled Foundations
- Deep-piled foundations are used to transfer load to a firm soil stratum with sufficient carrying capacity.
Piling Types
- There are two main types of piling: displacement and cast-in-place.
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Displacement piles are driven into the ground.
- Timber piles are low cost, renewable, and have a long history of successful applications.
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Precast concrete piles are higher strength because they are often prestressed.
- They can be manufactured to required lengths and splicing is not desirable.
- Closed-ended steel tube piles are used for various projects.
- Steel "H" section piles are another popular type depending on the project.
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Cast-in-place piles are formed in situ.
- Bulb piles form a large bulb at the bottom of the pile, which acts to spread the load.
- Bored piles are formed by drilling a hole in the ground and filling it with concrete.
Steel Fabrication Process
- Bolting is used to join steel components, either with ordinary bolts or high-strength friction grip bolts.
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Welding is another method used to join steel components:
- Shop welding is preferred over site welding due to better quality control.
- Welds require high-skill welders and must be inspected visually.
- Shop assembly is used for components that are brought together to be fitted up and inspected for dimensional accuracy, squareness, and conformance with shop drawings.
Steel Erection Tasks
- Secure Crane Information: Before crane lifts, obtain capacity and lifting limitations.
- Check Transport of Member Lengths: Ensure that pre-fabricated lengths and dimensions are suitable for transport routes.
- Decide Laydown Area: Choose a suitable area for temporary storage and staging of steel components.
- Determine Size of Yard Crane: Select an appropriate crane for lifting and positioning steel components.
- Determine Temporary Restraint Systems: Plan for temporary restraint systems to control the stability of steel elements during lifting and erection.
- Determine Painting Area (if needed): If painting is required, define an appropriate location for coating steel elements.
Crane Selection
- Avoid Marginal Situations: Ensure sufficient margin with crane capacities and operating conditions.
- Consider Three Dimensional Movements: Evaluate crane movements in three dimensions when choosing the right crane.
- Understand Characteristics of Different Types Select a crane based on its type, for example, rubber tyred or traced, lattice or telescopic, etc.
- Consider Operating Surface: Be mindful of the operating conditions and capabilities of the crane based on the surface.
- Beware of Multiple Crane Lifts: Exercise caution when using multiple cranes concurrently.
Steel Erection
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Option 1 - Assemble In Place: Steel elements are assembled in place using temporary support towers and wire rope guys.
- Crane location is not critical.
- Guys must remain in place until sufficient steelwork is erected.
- This method is time-consuming but allows for controlled progress.
- Option 2 - Assembled On Slab And Stood As Unit: Steel elements are assembled on a slab and lifted as a unit. This requires precise crane positioning and coordination.
Post-Tensioning
- Post-tensioning involves stressing against tendons that are not bonded to the concrete. Tendons pass through flexible ducting, which is cast into the concrete. The tendons are tensioned by jacking against concrete, anchored mechanically by anchorage blocks.
- Unbonded Construction: The remaining space in the ducts after stressing can be left empty.
- Bonded Construction: Ducts are filled with grout under high pressure.
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Description
This quiz explores the concepts of deep-piled foundations and their various types, including displacement and cast-in-place piles. It delves into the materials used, such as timber, precast concrete, and steel, and their applications in construction. Test your knowledge on how these foundations transfer loads to a firmer soil stratum.