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Foundation & their Importance in Building Construction

The foundation upon which a building is built is the most significant component. People might not take the time and effort to plan and design the foundation before having a building built. Even a lot of designers don’t prioritise foundations when designing. Buildings are supported by foundations, which transfer weight from the superstructure to the ground.

If the foundation is not constructed correctly, the building may eventually encounter significant structural issues. Without foundation, the columns’ bases will pierce the earth, making the structure unstable. The foundation aids in dispersing the weight of the columns over a larger region. 

The following points can basically illustrate why the foundation is so important:

Building Support:

The foundation is what keeps the entire structure level and carries the weight of the entire structure. To prevent cracking or buckling, it should be able to support both living and dead loads. The building may become unstable or possibly collapse if the foundation malfunctions or collapses at any moment. Pouring concrete is only one part of laying a foundation; it must also be appropriately shaped and stitched into the ground. In order to ensure load bearing, it should be compressed as needed.

Protection from Disasters:

Researching the local climate and ground conditions is important before building the foundation. Any natural disasters, such as earthquakes, cyclones, etc., won’t be able to weaken the foundation. The strength of the foundation is always planned in accordance with the severe natural disaster that has already happened in the particular area.

Protects from adjustment:

One of the main purposes of establishing a foundation is to safeguard the structure from settlement when it begins to gradually sink. The foundation’s shape and structure are created to withstand settlements that are greater than what is permitted by the area’s soil conditions.

 Classification of Foundation

According to the building construction and the soil conditions at the site, various foundation types must be constructed. Specific foundation types include two main categories: 

Shallow Foundation:

When soil at a short depth (up to 1.5 metres) can support the structural loads, shallow foundations are built. Shallow foundations typically have less depth than width. Shallow foundations are of four types:

Isolated Footing-

The most popular foundation type for single columns is called isolated footing. When the load of the structure is transferred through columns, an isolated footing with a square or rectangular shape is used. For vertical loads, square footings are utilised, while rectangular footings are used for eccentric loads. Three different types of isolated footing are pad footing, stepped footing, and sloping footing. In the event of a strong load from the superstructure, step footings are used.

Combined Footing-

Combined Footing is used in place of separate footings when two or more columns are too close to one another to prevent their overlapping. Additionally, it is used if the soil’s bearing capacity is lower than needed or if the column is close to property or sewer lines.

Spread Footing-  

Individual columns or walls are supported by these kinds of footings. These footings have a wider base than standard footings. The wider the base, the more evenly the load is distributed, and the more stable the structure will be. The soil’s bearing capacity must be sufficient to support the extra weight of the footing. When the bearing soil is less than 3 metres below the ground’s surface, these are also used for bridge piers.

Raft Footing:

Raft footing, often referred to as mat footing, is installed throughout the entire building to withstand large structural loads from the walls and columns. It is designed to stop individual footings from settling unevenly. As a result, it is intended to act as a raft or mat for the entire structure’s load-bearing components. It is applied to expansive soils, which have a low bearing capacity.

Deep Foundation:

In order to transport loads from a structure through weak compressible soils or fills and onto deeper, stronger, less compressible soils or rocks, or for functional reasons, a deep foundation is necessary. Deep foundations are submerged more than three metres below completed ground level, which is too deep for their base carrying capability to be impacted by surface conditions. If inappropriate soils are available close to the surface, the deep foundation can be utilised to transmit the loading to a deeper, more capable strata at depth. Deep foundations are of two types:

Pile Foundation:

To carry load from the footing base to the hard rock strata located relatively deep below the surface, pile foundations are used. These resemble thin columns that are cast or driven into the ground and made of steel, wood, or concrete. This is utilised to shift the load of the building to the hard rock stratum when the soil’s bearing capability is insufficient to do so. By using friction piles that create skin friction and end-bearing piles, pile foundations’ main function is to withstand loads.

Pier Foundation:

These foundations are usually used for bridge projects and foundations that need to be built below water. Huge, hollow, waterproof caissons are employed as piers for bridges or in the construction of dams. These are conveniently moved by floating in the water and sinking into the desired depth of ground or water. Concrete is then poured inside of them to create a foundation.

Functions of Foundation in Construction

According to the foundation’s intended uses in building, 

the following are the foundation’s primary tasks: 

  1. Make the structure’s lateral stability comprehensive.
  2. The purpose of a foundation is to provide a level surface for the erection of substructures.
  3. Even load distribution is achieved.
  4. The load intensity is decreased to remain within the soil’s safe bearing capacity.
  5. The effect of soil movement is resisted and avoided.
  6. The construction of a foundation resolves the problems of scouring and eroding.

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