Types Of Foundations :

Foundations may be defined in many types.The two types of foundations and their sub categories are:-
1.Shallow Foundations          2.Deep Foundations
1. Shallow Foundations:-Shallow foundations are furtherly categorise in folllowing types.
(i)Spread Footings:-spread footings are that types of foundations in which it spread the super-imposed load of wall or column over a larger area.Spread footings can supports either column or wall.
It can be of following types:-
(a) Single Footing
(b) Stepped Footing
(c) Sloped Footings
(d) Wall Footing Without Step
(e) Stepped Footing For Wall
(f) Grillage Foundation
(ii)Combined Footings:-It is types of foundations in which it supports two or more.The combined footings for the columns will be rectangular shape if they carry equal loads.The design for the rigid rectangular combined footing should be in such a way that the centre of gravity of column load coincide with the centroid of the footing area.If the columns carry unequal loads, the footings is of trapezoidal shape.The combined footings may be of the following types of foundations.
(a) Rectangular Combined Footing
(b) Trapezoidal Combined Footing
(c) Combined Column-Wall Footing
(iii)Strap Footings:-In this types of foundations the independent footings of two columns are connected by a beam.This type of foundations can be used where the distance between the columns is so large that a combined trapezoidal footings becomes a quite narrow,with high bending moments.In that case each columns is provided with its independent footings and a beam is used to connect the two footings.
(iv)Mat Foundation or Raft Foundation:-A raft or mat is a combined footing that covers the entire area beneath a structure and supports all the walls and columns.When the allowable soil pressure is low and the building load is high then the spread footings covers the area more than the one half of the area.Also it is economical to take in use.
 2. Deep Foundations:-It is a types of foundations in which the depth of the foundation is more than the width of the footings.This type of foundations are generally used in bridge,piers,etc.Furtherly it is categories in following types:-
(i) Deep strip, rectangular or square footing:-These foundations are the foundations in which footings are done deep to the earth in different shapes and connected with beams.
(ii) Pile Foundation:-Pile foundation is that type of deep foundation in which the load are taken in low level by means of vertical memebers such as timber,concrete,or steel.Pile foundation can be used in place of raft foundation.Piles used in building foundation are of four types End bearing pile,Friction Pile,Combined End Bearing And Friction Pile,Compact Piles
(iii)Pier Foundation or Drilled Caisson Foundation:-It consist of cylinderical column of large diameter to support and to transfer large superimposed loads to the firm strata below.Pier foundation is preferred in a location where the top strata is of decomposed rock overlying a strata of sound rock.Pier foundation is following types Masonary or Concrete Pier and Drilled caissons.
(iv) Well Foundation:-Well Foundations are box like struxture which is sunk from the surface of either land or water to the desired depth.Its diameter is larger than the other foundations or footings.Well Foundations are used for major works like bridge, piers, and abutments in rivers, lakes etc, also for wharves, quay walls, docks, to break waters and other structures for shore protections.

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