Foundation
Definition:
Foundation is one of the essential parts of the structure. It is defined as that part of the structure that transfers the load from the structure constructed on it as well as its weight over a large area of soil in such a way that the amount does not exceed the ultimate bearing capacity of the soil and the settlement of the whole structure remains within a tolerable limit. Foundation is the part of a structure on which the building stands. The solid ground on which it rests is known as foundation bed.
Type of Foundation:
- Shallow Foundation
- Deep Foundation
- Wall Footing or Strip Footing
- Isolated or Single Footings
- Combined Footings
- Cantilever or Strap Footings
- Continuous Footings
- Raft or Mat Foundation
- Pile Foundation
- Pier Foundation
- Caisson Foundation
- Copperdam Foundation
Isolated or single footings are used to support single columns. This is one of the most economical types of footings and is used when columns are spaced at relatively long distances.
Combined footings usually support two columns, or three columns not in a row. Combined footings are used when two columns are so close that single footings cannot be used or when one column is located at or near a property line.
Cantilever or strap footings consist of two single footings connected with a beam or a strap and support two single columns. This type replaces a combined footing and is more economical.
Continuous footings support a row of three or more columns. They have limited width and continue under all columns.
Rafted or mat foundation consists of one footing usually placed under the entire building area. They are used, when soil bearing capacity is low, column loads are heavy single footings cannot be used, piles are not used and differential settlement must be reduced.
Pile Foundation are thick slabs used to tie a group of piles together to support and transmit column loads to the piles.
Pier Foundation is a vertical column of a relatively larger cross-section than a pile. A pier is installed in an adry area by excavating a cylindrical hole of a large diameter to the desired depth and then backfilling it with concrete.
Caisson foundation also called as pier foundation is a watertight retaining structure used as a bridge pier, in the construction of a concrete dam, or for the repair of ships. It is a prefabricated hollow box or cylinder sunk into the ground to some desired depth and then filled with concrete thus forming a foundation.
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