CENG 302: Construction Engineering Chapter 3 - Foundations

Foundations

• A foundation is a structural part of a building that safely sustains and transmits loads to the ground.
• The function of a foundation is to prevent settlement or movement that would impair the stability or cause damage to the building.

Selection of Foundation

• The selection of a foundation type is based on factors such as:
  • Adequate depth to prevent damage
  • Bearing capacity failure
  • Settlement
  • Adequate strength to resist fracture or breakage
  • Seismic forces to support the structure during earthquakes

Types of Foundations

• Shallow foundations:
  • Constructed where soil layers at shallow depths can support structural loads
  • Examples: Isolated Pads (Spread), Combined, Strips (Wall), Raft (Mat) Foundations
  • Depth is generally less than its width
• Deep foundations:
  • Transfer loads through weak, compressible soils to underlying competent soils or bedrock
  • Examples: Piles, Micro-piles, Caissons
  • Depth is generally greater than 5m

Types of Footings

• Spread (Pad) Footing
• Strip (Wall) Footing
• Combined Footing
• Pilecap Footing
• Strap (Cantilever) Footing
• Raft (Mat) Footing

Deep Foundations

• Include piles, micro-piles, and caissons
• Piles:
  • Vertical or slightly inclined members used to transmit loads to lower layers
  • Can be used when suitable foundation conditions are not present at or near ground level
• Materials used for piles: concrete, steel, and timber
• Pile components: pile head, shaft, and pile tip

Piled Foundations

• According to design:
  • End Bearing Piles: terminate in hard, relatively impenetrable material
  • Friction Piles: do not reach an impenetrable stratum but are driven into a penetrable soil
• According to construction:
  • Displacement Piles: displace the soil to allow for pile penetration
  • Non-displacement (or replacement) Bored Piles: remove soil to accommodate the pile

Pier Foundations

• A deep foundation system similar to a cast-in-place pile
• Consists of a column-like reinforced concrete member
• Also referred to as drilled shafts, bored piles, or drilled caissons

Pile Testing

• Methods to test the capacity and integrity of piles
• Important for ensuring the safety and stability of the structure

Retaining Walls

• Structures used to resist lateral earth pressures
• Types of retaining walls:
  • Gravity walls
  • Cantilever walls
  • Counterfort walls
  • Anchored walls

Test your understanding of foundations, a crucial structural part of a building. This quiz covers the function of foundations, load transmission, and stability. Perfect for Civil Engineering students!