FOUNDATIONS

FOUNDATIONS

1. Definition:

   • Foundation of a structure, supports the weight of the structure and the applied loads. Includes: ✓ The soil or rock upon which the structure rests ✓ As well as the structural system designed to transmit building loads to the supporting soil or rock. . Foundation forms part of the sub-structure: part located below the surrounding ground surface.

2. Foundation Failure:

   • refers to collapse or excessive settlement of a building’s support structure resulting from soil movement or consolidation rather than from failure of the foundation structure itself.

3. Types of foundation systems:

   • Spread Footings:
     • ✓ Simplest, most common type of building foundation
       • Usually consists of a square or rectangular reinforced concrete pad that serves to distribute loads over an area large enough so that the resulting pressure on the supporting soil does not exceed the soil’s allowable bearing strength
         • Include: ❖ Individual footings ▪ Isolated (single) footings – supports a single column ▪ Wall footings – supports a wall
           • Combined footings ▪ Support a wall and 1 or more or several columns
             • Mat/Raft Foundations
               • ➢ Heavily reinforced concrete slab
                 • ➢ Extending under the entire structure
                   • ➢ In order to spread the structure’s load
                     • ➢ Over a large area
               • ➢ Usually employed for large (foot print) buildings, they sometimes, involve deep excavations and large – scale concrete pours
                 • ➢ For residential purpose, usually constructed on an earth mattress created from imported fill with ground beams excavated into this constructed layer
               • Floating foundation
                 • is a type of mat foundation in which the weight of the soil excavated
                   • approximately equals the weight of the structure being erected,
                     • thus no change to the load on the soil
                       • hence no settlement of the structure – reinforced as per raft foundation.
   • Piles:
     • ➢ A column driven into the soil
       • ➢ To support a structure
         • ➢ By transferring building loads
           • ➢ To a deeper and stronger layer of soil or rock
             • ➢ Classified as either end-bearing or friction piles according to which the pile load are resisted.
               • ➢ All piles basically supported by skin friction and end-bearing
                 • Pile Types:
                   • 1. Timber:
                     • 2. Pre-cast Concrete:
                       • 3. Cast-in-place/ cast-in-situ concrete piles:
                         • 4. Steel piles:
                           • 5. Composite piles:
                             • 6. Bulb piles:
   • Piers & Caissons:
     • A pier is simply a column
       • usually of reinforced concrete
         • constructed below ground surface
           • to transfer the load of a structure down to a stronger rock or soil layer.
             • May be constructed in: ❖ An open excavation ❖ Lined excavation (caisson) ❖ Drilled excavation
               • A caisson is a structure used to provide all-around lateral support to an excavation: Manhattan bridge, NY
                 • May either open or pneumatic where pneumatic caissons are air and water tight structures open on the bottom and to permit excavation of soil beneath the caisson.

Imagens e arquivos do mapa