Thursday, July 7, 2016
Shallow Foundation Definition & its types
A foundation is described as the lower most combined part of a structure, that is connected with the soil directly as well as securely transfers the complete load of the structure maintaining the completely strength of the structure to the soil underneath. To make a structure stable, the foundation conveys all the loads generated from the structure to the solid soil layer at specific depth, A foundation also provides lateral strength to the structure in order that it abstain from Sliding or Overturning.
There usually exist two types of Foundation a) Deep Foundation b) Shallow Foundation:
Deep Foundation: If the extent of the lower most portion of the foundation is below the depth of the lower most portion of the foundation from the top of the soil i.e. ground level then it is known as a Deep Foundation.
Deep foundation is ideal for heavily loaded structures like High Rise Buildings, Bridges and Flyovers etc. Deep foundation is required in case of the quality of the soil is inferior.
Shallow Foundation: If the extent of the lower most section of the foundation surpasses the depth of the lower most section of the foundation from the top of the soil i.e. ground level then it is known as a Shallow Foundation.
For various light and tolerably loaded structures like 5 storied residential buildings and other general type of works shallow foundation should be build up, but the soil should not contain inferior quality with extremely collapsible soil and low bearing capability.
Shallow foundation can be subcategorized on the basis of the site condition as well as type of loading and pattern.
Isolated Column Footing: Isolated Column Footing refers to a very normal type of foundation, and is useful for Framed Structure, Combined Framed and Load Bearing Structure for developing the foundation of a single column only. For all separate columns, an isolated column footing is to be constructed with. This type of foundation is available in two types - a footing containing unvarying depth at all points of the footing and a footing that is slopped from the face of the column in the direction of the edge of the footing. Sloped footing is much cost effective as compared to footing having identical depth.
Combined Footing: This footing are useful if the footing area of one column extends over the footing area of the other column. Under this type of foundation, there are two or more columns built inside a single Footing, which range from rectangular or trapezoidal based on the loading pattern on the columns to be supplied with Combined Footing. If all columns contain almost uniform load on them then Rectangular Footing is applied and if the loading diverges mostly then Trapezoidal Footing is needed, the width being larger to lesser from the side of column containing higher load the column supporting relatively lesser Loads.
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