Foundations

Foundations

1. A connected part of a building

   • extended to soil where it recieves imposed load and spreads t/out soil

2. func. (6)

   • prevents
     • settlement of a structure
     • possible movement of structure
       • due to periodic shrinkage & swelling of subsoil
     • uplifting/overturning forces due to wind
     • lateral forces due to soil movement
   • allows
     • overwater buildings
     • underpin existing & unstable structures

3. factors (4)

   • soil cond.
     • soil bearing cap.
       • water table
         • chemical
   • load
     • live, dead, wind
   • tech
     • expertise
       • skilled labour
   • cost
     • materials & machinery

4. types

   • simple, shallow, deep foundation
     • spread foundation
     • mat/raft foundation
       • raft fdtion
         • large combi thick slab to seat & support large prt of struct
         • used when-
           • subsoil is weak
           • columns closely located w/ different loading
         • is a transfer slab
           • to combine all vertical loading elemnts to the plate form fdtion so dif settlement can be avoided
         • load is transfered directly from floor slab to soil
         • ok for low bearing cap soil
         • types
           • solid slab
             • bi-direction reinforcement
           • beam and slab
             • used when thicness of slab is more then 350mm
           • cell
             • used when thickness of slab is more than 1m
     • shallow foundation
       • foundation that rests on stratum (layers of rocks on ground) with ok bearing capacity and is less than 3m below gd lvl
       • ex: pad, strips, raft
   • pad / strip type, piled foundation
     • pile
     • pile walls
     • caissions
     • diaphragham wall
     • pad foundations
       • resedential & 2 storey building
       • load transfered tru column
       • shape: square
       • made from concrete
       • conc. mix ratio- 1:2:4 20mm = dia of agg
         • 1 cement
         • 2 sand
         • 4 aggregates
       • reinforcement- up tensile strength of conc.
       • sub types
         • integrated pad fdations-
           • 2 dif type of integrated pd fdation
         • strip pad fdations
           • combi od pad + strip fdation
       • process of pad fdtion
         • marking
           • excavation
             • mat prep
               • formwork
                 • reinforcement
                   • concreting
                     • mixing
                     • pouring
                     • curing
                     • testing
               • reinforcement
               • formworks
               • cement
               • sand
               • aggregates
               • stones
     • strip foundation
       • made of conc
       • ratio 1:3:6 40mm of agg
       • types
         • ordinary
           • 1 & 2 storey cons
           • high capicity bearing soil
         • wide
           • low bearing capicity soil
           • soft clay moist & filled soil
         • deep
           • soil vunr. to damp spot
           • clay that shrink & expand acc. to weather
       • cons procss like pad
     • pile fdtion
       • types
         • pre-cast
         • in-situ
         • classi.
           • end bearing pile/ friction pile
           • piles by mech or manual methods
           • percussion or non percussion
           • di sor re placement
       • used when
         • stable soil is more tehan 3m deep
           • its not suitable to use raft, pad, strip fdtion as excavation wrks is exsp
         • exp & complicated ground water removal
         • other fdation is ko
       • is a form of fdtion, uses piles to transfer loads to firm soil stratum that can take load very ok
       • materials
         • timber
         • re-cast conc
         • in-situ reind. conc
         • steel piles in H or circular sect