On the basis of ground/soil condition :-
1.Shallow foundations are preferred where soil close to the surface is capable of supporting structure loads. Where the ground close to the surface is not capable of supporting structural loads.
2. Hard strata is searched for and deep foundation is required, example rock strata.
3.Uniform stable ground requires relatively shallow foundation whereas filled up ground has low bearing capacity thus requires deep foundation.
On the basis of Loads from Building :-
1. In the case of low-rise building in a larger area, the extent of loading is relatively low, so shallow foundation can resist the load from the structures.
2. In the case of the high-rise building built within less area have high loads. Therefore, the deep foundation is required as shallow foundation may not be able to resist such loads of greater intensity.
Types Of Footings :-
1. Foundations provide support for structures, transferring their load to layers of soil or rock that have sufficient bearing capacity and suitable settlement characteristics.
Very broadly, foundations can be categorised as shallow foundations or deep foundations. Shallow foundations are typically used where the loads imposed by a structure are low relative to the bearing capacity of the surface soils. Deep foundations are necessary where the bearing capacity of the surface soils is not adequate to support the loads imposed by a structure and so they need to be transferred to deeper layers with higher bearing capacity.
Strip foundations (or strip footings) are a type of shallow foundation that are used to provide a continuous, level (or sometimes stepped) strip of support to a linear structure such as a wall or closely-spaced rows of columns built centrally above them.
Strip foundations can be used for most subsoils, but are most suitable for soil which is of relatively good bearing capacity. They are particularly suited to light structural loadings such as those found in many low-rise or medium-rise domestic buildings - where mass concrete strip foundations can be used. In other situations, reinforced concrete may be required.
2. A Combine footing is a component of a building’s foundation. It is a type of combined footing, consisting of two or more column footings connected by a concrete beam. This type of beam is called a strap beam. It is used to help distribute the weight of either heavily or eccentrically loaded column footings to adjacent footings.
A Combine footing is often used in conjunction with columns that are located along a building’s property or lot line. Typically, columns are centered on column footings, but in conditions where columns are located directly adjacent to the property line, the column footings may be offset so that they do not encroach onto the adjacent property. This results in an eccentric load on a portion of the footing, causing it to tilt to one side. The strap beam restrains the tendency of the footing to overturn by connecting it to nearby footings.
Combined Footing
3. A deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths. A pile or piling is a vertical structural element of a deep foundation, driven or drilled deep into the ground at the building site.
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VERY HELPFUL ARTICLE THANKSS!!
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