Group 7

Group MembersUmar Khatab 2013-BT–CIVIL-36 Abid Javaid 2013-BT–CIVIL-09

FOOTING AND ITS TYPES

FootingThe lowest load-bearing part of a building,

typicallybelow ground level is called footingTypes of FootingThere are three main types of foundation• Strip footing• Raft/Mat footing• Isolated/Pad footing

Footing

STRIP FOOTING

Strip FootingA continuous strip of

concrete under a continuous wall carrying a uniformly distributed load

Footing spread is usually provided

Strip FootingFooting spread (150mm on each side) is usually provided:i. To facilitate bricklayer a “working space”

for building the lower courses of wallsii. To provide “stability” to the load-bearing

walls before it is tie down by floors and roofiii. To provide “working space” for the hand

excavation operation in deeper trench excavation

Wide Strip Footing

Wide Strip FootingUse in a situation

where the load bearing capacity of the soil is low

(e.g. soft clay silt, made ground)Site which may be

subjected to “unequal settlement” (mining areas), or where the subsoil is “not uniform” in character

Inverted ‘T’ Beam Strip Footing

Inverted “T” Beam Strip Footing Use in a situation

where there is a danger of the foundation failing as a beam in the longitudinal direction

Deep Strip Footing

Deep Strip FootingA deep strip footing is a narrow footing which is used for normal soil and normal loads and is made 0.9m deep.

Deep Strip FootingIn a deep, narrow trench

Excavation by hand is not possible

Brickwork cannot be built up from the bottom

Excavation by mechanical means is possible

Stepped Strip Footing

Stepped Strip FootingA stepped strip foundation is often used on a sloping site where the steps allow the foundation to follow the slope without too much excavation, when compared with excavations and retaining walls.

Abid Javaid

2013-BT-CIVIL-09

RAFT/MAT FOOTING

Raft/Mat Footing Raft footing is a

continuous footing that supports an entire structure, such as a floor also known as foundation mat.

Raft/Mat FootingBest suited in the following conditions:Column loads are extremely heavy, thus

requiring large basesColumns are closely spaced in both directions

and if pad footings are used, it would overlap and may almost cover the whole building area

Ground bearing capacity is low, such as in compressible soft natural

Types of Raft/Mat FootingSolid Slab Raft-flat concrete slabs have

uniform thickness over whole raft area, with pedestals or without pedestals

Beam and Slab Raft Footing-beam and slab rafts are alternatives to the solid slab raft and are used where poor soils are encountered, have pedestals

Cellular/Framed Raft Footing-these type of foundations are used on soft compressible subsoil such as soft clay or pit.

ISOLATED/PAD FOOTING

Isolated/Pad Footing Pad footing is the

support used at a point load such as columns or framed structures. They may be circular, square or rectangular and consist of a block or slab of the thickness.

Isolated/Pad FootingThe pad footing may be stepped if they are

required to spread the load from a heavy column. The pads are usually shallow but deep ones can be found depending on the structure.

Isolated or independent slab of concrete foundation to support concrete columns or steel pillars, detached brick or masonry piers

The pier or column bearing on the centre point of the slab

Isolated/Pad FootingVariation of pad footings:

Combined Footings – used where the bearing areas of closely spaced columns overlapped

Cantilever Footings – designed to accommodate eccentric loads

Referenceshttp://www.ask.com/question/http://www.ekt.bme.hu/ArchEng/

Foundations%20(S-D)-s.pdfhttp://en.wikipedia.org/wiki/Foundation_(engi

neering)

http://www.architectural-world.com/2008/04/architectural-presentation-raft.html