SHALLOW FOUNDATION

MOINUDDINB.ARCH 3RD YR

•DEFINITION OF FOUNDATION

The lowest part of a structure is generally referred to as foundation.

•FUNCTION OF A FOUNDATION

To transfer load of the superstructure to the soil on which it is resting.

•REQUIREMENTS

A properly designed foundation is one that transfers the structural load throughout the soil without overstressing of soil which can result in either excessive settlement or shear failure, both of which can damage the structure.

LOADS ON FOUNDATION

Dead Load : Refers to the overall weight of the structure. Includes weight of the materials permanently attached to the structure (such as flooring) and fixed service equipment (such as air conditioning)

Live load : Refers to the weight of the applied bodied that are not permanent parts of the structure. Applied to the structure during part of its useful life (e.g. people, warehouse goods). Specified by code.

Wind loads : Acts on all exposed parts of the structure. Calculated using building codes.

Earthquake Forces : Building code is consulted.

CLASSIFICATION NOF FOUNDATIONS

•SHALLOW FOUNDATION

•DEEP FOUNDATION

SHALLOW FOUNDATION

This type of foundation usually refers to those being rested on stratum with adequate bearing capacity and laid less than 3m below ground level. Common examples include pad, strip or raft foundations.The selection of the right type of shallow foundation normally depend on

the magnitude and disposition of the structural loads and the bearing capacity of subsoil. A combination of two or three type of shallow foundation in one single structure is not uncommon.

TYPES OF SHALLOW FOUNDATION

TYPES OF SHALLOW FOUNDATION………..

PAD FOUNDATION / SQUARE SPREAD FOOTING FOUNDATION

•Support a single centrally located column

•Use concrete mix 1:2:4 and reinforcement

•The reinforcement in both axes are to resist/carry tension loads.

PAD FOUNDATION / SQUARE SPREAD FOOTING FOUNDATION……..

Circular Spread Footings

• Are round in plan view

• Most frequently used as foundation

for

• Light standards, flagpoles and

power

• Transmission lines.

CONTINUOUS SPREAD FOOTINGS / STRIP FOUNDATION

•Used to support bearing walls

COMBINED FOOTINGS

• support more than one column

• useful when columns are located too close together for

each to have its own footing

RAFT FOUNDATION

Raft foundation is a large combined thick slab designed to seat

and support the whole or a large part of a structure.

A raft is usually used when subsoil is weak, or columns are closely

located and with deviated loadings. It also serves as a transfer slab to

combine and tie up all the vertical loading elements to the plate-form

foundation. By doing so, differential settlement can be avoided.

ADVANTAGES AND DISADVANTAGES OF SHALLOW FOUNDATION

ADVANTAGES:

•Cost (affordable)

•Construction Procedure

(simple)

•Materials (mostly concrete)

•Labor (does not need

expertise)DISADVANTAGES:

•Settlement

•Limit Capacity Soil Structure

•Irregular ground surface (slope, retaining

wall)

•Foundation subjected to pullout, torsion,

moment.