Footing and Its Types

types of footing

1. Group 7 Group Members Umar Khatab 2013-BT–CIVIL-36 Abid Javaid 2013-BT–CIVIL-09

2. FOOTING AND ITS TYPES

3. Footing The lowest load-bearing part of a building, typically below ground level is called footing Types of Footing There are three main types of foundation Strip footing Raft/Mat footing Isolated/Pad footing

4. Footing

5. STRIP FOOTING

6. Strip Footing A continuous strip of concrete under a continuous wall carrying a uniformly distributed load Footing spread is usually provided

7. Strip Footing Footing spread (150mm on each side) is usually provided: To facilitate bricklayer a “working space” for building the lower courses of walls To provide “stability” to the load-bearing walls before it is tie down by floors and roof To provide “working space” for the hand excavation operation in deeper trench excavation

8. Wide Strip Footing

9. Wide Strip Footing Use 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

10. Inverted ‘T’ Beam Strip Footing

11. 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

12. Deep Strip Footing

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

14. Deep Strip Footing In a deep, narrow trench Excavation by hand is not possible B rickwork cannot be built up from the bottom E xcavation by mechanical means is possible

15. Stepped Strip Footing

16. Stepped Strip Footing A 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.

17. Abid Javaid 2013-BT-CIVIL-09

18. RAFT/MAT FOOTING

19. Raft/Mat Footing Raft footing is a continuous footing that supports an entire structure, such as a floor also known as foundation mat.

20. Raft/Mat Footing Best suited in the following conditions: C olumn loads are extremely heavy, thus requiring large bases C olumns are closely spaced in both directions and if pad footings are used, it would overlap and may almost cover the whole building area G round bearing capacity is low, such as in compressible soft natural

21. Types of Raft/Mat Footing Solid 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 C ell ular/Framed Raft Footing- these type of foundations are used on soft compressible subsoil such as soft clay or pit.

22. ISOLATED/PAD FOOTING

23. 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.

24. Isolated/Pad Footing The 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

25. Isolated/Pad Footing Variation of pad footings: C ombined F ootings – used where the bearing areas of closely spaced columns overlapped Cantilever F ootings – designed to accommodate eccentric loads

26. References http:// www.ask.com/question/ http://www.ekt.bme.hu/ ArchEng / Foundations %20(S-D )- s.pdf ‎ http://en.wikipedia.org/wiki/Foundation_(engineering ) http://www.architectural-world.com/2008/04/architectural-presentation-raft.html