Foundation Systems Quiz
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Questions and Answers

What is the main advantage of using concrete piles over wooden piles?

  • Lighter weight
  • Resistance to decay and marine worms (correct)
  • Lower initial cost
  • Easier installation

    • How far should a timber grillage be kept below the lowest recorded water line?

  • At least 2 inches
  • At least 1 foot
  • No specific requirement
  • Completely below (correct)

    • What type of concrete pile is generally molded before being driven?

  • Pre-cast pile (correct)
  • Timber pile
  • Plain concrete pile
  • Reinforced concrete pile

    • Why do wooden piles need to be cut off underwater?

    <p>To avoid alternately wet and dry conditions</p> Signup and view all the answers

    What is typically placed between the driving block and the concrete in a driving head for pre-cast piles?

    <p>A cushion of sand or rope</p> Signup and view all the answers

    What spacing is generally used for concrete piles?

    <p>2 feet to 6 inches to 4 feet</p> Signup and view all the answers

    What component helps attach adjacent sticks in timber construction?

    <p>Driftbolt</p> Signup and view all the answers

    What is a requirement for concrete piles when a steel casing surrounds them?

    <p>Must extend at least 4 inches into the footing</p> Signup and view all the answers

    What primarily supports friction piles?

    <p>Frictional resistance of surrounding earth mass</p> Signup and view all the answers

    What is the minimum diameter for wooden piles used in heavy buildings?

    <p>8 inches</p> Signup and view all the answers

    What type of hammer is increasingly replacing the ordinary drop-hammer in pile driving?

    <p>Steam hammer</p> Signup and view all the answers

    What is the main purpose of a mat foundation?

    <p>To distribute loads evenly over low bearing capacity soil</p> Signup and view all the answers

    What is a key consideration when driving wooden piles?

    <p>Keeping the piles plumb</p> Signup and view all the answers

    What is a key characteristic of steel grillage foundations?

    <p>They involve the use of steel rails or beams.</p> Signup and view all the answers

    What occurs when a pile refuses to sink under several blows?

    <p>The pile should be cut off and another one driven beside it</p> Signup and view all the answers

    Under what conditions are deep foundations typically used?

    <p>When soil is unstable or has inadequate bearing capacity.</p> Signup and view all the answers

    When using a drop-hammer for driving piles, what should be the hammer's fall adjustment when penetration becomes small?

    <p>Decrease to about 5 ft.</p> Signup and view all the answers

    What is the purpose of a pile cap in pile foundations?

    <p>To connect and distribute the loads across multiple piles.</p> Signup and view all the answers

    What is characterized by the number of blows delivered by a steam hammer?

    <p>60 to 70 blows per minute</p> Signup and view all the answers

    End bearing piles primarily rely on which type of support?

    <p>The bearing resistance of soil or rock beneath them.</p> Signup and view all the answers

    What is the consequence of using excessive blows on a pile that has reached its limit of penetration?

    <p>Crushing and splitting of the pile</p> Signup and view all the answers

    What minimum thickness of concrete is recommended beneath steel grillage foundations?

    <p>6 inches</p> Signup and view all the answers

    Which of the following is NOT a type of deep foundation?

    <p>Mat foundations</p> Signup and view all the answers

    What is a critical aspect of placing beams in a steel grillage foundation?

    <p>The clear space between the flanges should not be less than 2 inches.</p> Signup and view all the answers

    What is a defining characteristic of cast-in-place piles?

    <p>They are formed from hollow cylindrical steel tubes driven into the ground.</p> Signup and view all the answers

    Which type of cast-in-place pile is referred to as an 'uncased pile'?

    <p>Simplex piles</p> Signup and view all the answers

    What distinguishes steel piles from other types of piles?

    <p>They are concrete-filled steel pipes designed to bear on rock or hard pan.</p> Signup and view all the answers

    What method is used to form caissons?

    <p>Boring with a large auger and filling the shaft with concrete.</p> Signup and view all the answers

    What is the typical diameter range of steel pipes used in steel piles?

    <p>10 to 18 inches</p> Signup and view all the answers

    In the construction of a pedestal pile, what is done after the steel driving core is removed?

    <p>Concrete is poured into the formed hole.</p> Signup and view all the answers

    Which statement is true regarding the driving process of steel piles?

    <p>They can be driven in sections using steam-hammers.</p> Signup and view all the answers

    What is a common element in the composition of all types of cast-in-place piles?

    <p>Inclusion of some form of concrete.</p> Signup and view all the answers

    What is the primary function of a foundation system in construction?

    <p>To transfer lateral loads to the ground</p> Signup and view all the answers

    Which type of foundation is best suited for stable soil located near the ground surface?

    <p>Shallow or spread foundations</p> Signup and view all the answers

    What distinguishes individual or isolated footings from other types of foundations?

    <p>They support free standing columns and piers</p> Signup and view all the answers

    What purpose do combined foundations serve?

    <p>To support two or more columns where individual footings cannot be centered</p> Signup and view all the answers

    What is a key characteristic of cantilevered footings?

    <p>They connect multiple columns with a tie-beam or strap</p> Signup and view all the answers

    Continuous footings can serve which of the following functions?

    <p>Supporting a row of columns or all columns by strips at right angles</p> Signup and view all the answers

    What design consideration is crucial for combined column footings?

    <p>The center of gravity of the loads must align with the center of gravity of the footing area</p> Signup and view all the answers

    What defines the primary use of strip footings in construction?

    <p>They are continuous spread footings supporting foundation walls</p> Signup and view all the answers

    What is the purpose of the iron pile ring?

    <p>To prevent the pile from splitting</p> Signup and view all the answers

    In which soil condition do piles drive better with a square point?

    <p>When driven in soft and silty soils</p> Signup and view all the answers

    What is the usual spacing requirement for driving piles?

    <p>At least 2 ft on centers</p> Signup and view all the answers

    What is the maximum allowable load on wood piles?

    <p>20 tons</p> Signup and view all the answers

    What type of cap is usually preferred for piles and how thick is it typically?

    <p>Reinforced concrete cap, usually 18 inches or more in thickness</p> Signup and view all the answers

    What should be done to piles that will be driven in or exposed to salt water?

    <p>Treat them with creosote, dead oil, or coal-tar</p> Signup and view all the answers

    When capping piles with timber grillages, what is the minimum cross-section size for the timbers?

    <p>10” x 10”</p> Signup and view all the answers

    What may happen if long piles are driven closer than 2 ft on centers?

    <p>They may force each other up from their solid bed</p> Signup and view all the answers

    Study Notes

    Foundation Systems

    • Foundation systems transfer loads from structures to the ground.
    • Two main types: shallow and deep foundations.

    Shallow Foundations

    • Used when stable soil with adequate bearing capacity exists near the surface.
    • Transfer loads directly to supporting soil.
    • Types include:
      • Individual/isolated footings:
        • Block or square footings
        • Stepped footings
        • Slope or pyramidal footings
      • Strip footings: continuous footings for foundation walls. Can be stepped to accommodate sloping grades.
      • Combined footings: support two or more columns. Designed so the center of gravity of the footing area coincides with the combined loads.
      • Cantilevered footings: connect exterior and interior columns with a tie-beam or strap. The strap sits level with the top of footings.
      • Continuous footings:
        • Support a line of columns.
        • Support all columns with strips at right angles to each other.
        • Can also be inverted slab or inverted tee continuous footings.
      • Mat/raft foundations: used when the soil has low bearing power and unequal settlement is a concern. All parts of the foundation are interconnected to act as one. Types include:
        • Flat slabs of plain or reinforced concrete.
        • Beams or girders with a slab underneath.
        • Beams or girders with a slab on top.

    Deep Foundations

    • Used when the soil underlying a shallow foundation is unstable or inadequate.
    • Transfer loads to a more stable stratum (rock or dense material) below the superstructure.
    • Types include:

      • Pile foundations:

        • System of end-bearing or friction piles, pile caps, and tie beams to transfer loads.
        • End bearing piles: depend on soil/rock resistance.
        • Friction piles: depend on friction between the pile and soil.
        • Wood piles: made from tree trunks. Driven by a drop-hammer or steam-hammer.
        • Concrete piles: molded in place or pre-cast. Used on land or in water. Preferable to wooden piles if the area is prone to water damage.

      • Steel grillage foundations: use steel rails or beams to distribute load over a wide area for a minimum of depth, usually when excavation should be avoided.

      • Caisson foundations: cast-in-place concrete pier formed by boring, usually with a large auger or excavating a shaft. May also be called drilled piles or piers. Rock caissons use an H-section core within the concrete.

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    Description

    Test your knowledge on foundation systems, focusing specifically on shallow foundations. This quiz covers different types of shallow foundations, their purposes, and characteristics. Understand how different footings work to transfer loads from structures to the ground.

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