Types of footings, their uses, and how to choose the appropriate type

 The foundations of buildings are classified into superficial foundations and deep foundations, and under each section there is a type of foundation that we will review in this topic and find out when each of them is used.

It is best to know the suitability of each of these types of foundations before choosing them for any construction project.

The goal of executing foundations for structures

The function of foundations or bases is as follows:

     The main function of foundations is to distribute the total weight of the structure over a larger area.
     Foundations are constructed to provide a suitable flat surface for building the superstructure of a building.
     There may be chances of subsidence of the structure or building due to the heavy load on the soil. Proper foundations help prevent differential unequal subsidence.
     Foundations provide stability to the structure and prevent tipping by taking the total weight of the structure deep into the ground.
     Foundations are not provided to support the load of the structure but, in fact, act as a means of transferring the load of the building to the soil below the foundation.
     Foundations are provided to prevent lateral movement of the structure and increase structural stability. 

Basic requirements for the implementation of good foundations for structures

The following are the basic requirements for good foundations:

     Foundation site
     Foundation balance and stability
     Durability and durability of foundations
     Foundation subsidence

#1. The location and location of the foundations

The foundations shall be laid and located so that they can withstand any unexpected impact that may appear in the future on the structure in addition to adhering to the depth of excavation and foundation mentioned in the project soil examination report. Therefore, care must be taken while designing the foundation layout.
#2. Foundation stability and stability

Stability or structural stability of building foundations is a very basic requirement for building a good foundation. The foundation must be stable and secure to resist any subsidence. Good foundations must be solid to support overlapping loads that may be unevenly distributed.
#3. Foundation durability

The foundations should be designed and constructed in such a way as to make them sturdy and resistant to the heavy load of the structure in addition to applying proper protection to these foundations against external influences such as foundation soil, backfill, groundwater, rain, etc.
#4. Foundation subsidence

The subsidence of the foundations of the building depends on the bearing capacity of the soil. The soil on which the foundations will be built must be more solid and compacted or compacted to avoid subsidence of the foundations. The foundations must be built so that they do not sag under the superimposed heavy load in excess of the values allowed in the building codes.

Types of foundations and their uses

     Soil bearing capacity depends on site conditions. It varies from site to site. Engineers should design different types of foundations according to the bearing capacity of the soil and site conditions.
     Thus the same type of foundation cannot be built for every site. Depending on the soil shape, volume, composition and load of the structure, different types of foundations are used.
     If the foundations of such buildings are constructed without understanding the soil conditions of the project, it may lead to foundation failure.
     When foundation failure or collapse occurs, it is difficult to improve the situation.

The foundations are divided into:

1- Surface foundations

It is the type of foundations that are executed close to the surface of the earth, where the foundation depth is less than twice the width of the foundation.

It is always recommended to use this type for its ease of implementation and also at a lower cost than deep foundations after the safety conditions are met. It is divided into:

     Separate Rules
     bar rules
2 Deep foundations

When the surface layer is weak or there are huge loads, the surface layers cannot bear the stresses, so this layer is penetrated to a suitable depth in search of a solid and suitable layer for the foundation. These types are called deep foundations, including:

     piles
     caissons

Types of superficial foundations

1- Separate rules
separate base

Where each column has a single independent base in the form of a square or rectangle, and it transfers the live and dead loads to the foundation soil, and it is preferred in cases of strong soils and buildings with few floors.

Base dimensions depend on the load and the foundation soil bearing value, where the load is divided by the allowable soil bearing capacity and can be designed manually to obtain the appropriate reinforcement or by using construction programs.
2- Common Rules

It appears from its name that it is the base that carries more than one column and is used when two or more separate bases overlap and has upper and lower reinforcement and must be accurately calculated manually or with the help of programs.
3- Tape base
Strip rules

It is the base whose length is much greater than its width and carries a large group of columns in the form of a group of longitudinal and transverse rows. It can support a wall (wall) instead of columns. This type of foundation gives greater stability to buildings than separate ones.

It is not preferable to use them in the event that a large flow of groundwater is expected over the foundation soil.
4- Armed dressing
Basis for a basha

It is to place all the columns of the building on one base with the entire area, and it is usually used in weak lands and when the total area of ​​the separate bases exceeds 60 percent of the building area.

The grout is very useful in preventing the uneven subsidence of the separate foundations and gives greater stability and bears huge loads and weights, but it is not preferable to use it except over deep piles or foundations in the case of water flowing on the surface of the soil or the presence of the water level higher than the foundation level to avoid liquefaction, liquefaction or buoyancy. It is always preferable to design this type of foundation using engineering programs, and its reinforcement is upper and lower, and it is possible to need additional iron, and it is considered the most expensive surface foundation.

Types of deep foundations

piles


It is used when the foundation soil close to the surface cannot bear the weight of the structure using any type of surface foundation. Piles can resemble columns in shape, as they are used to transport huge building loads to the strong layers of the earth at a depth of 5 meters to 50 meters. They transfer the load with the force of friction and the end of fixation on solid soil. They may carry separate bases or reinforced piles on top of them.

Piles give greater stability against slump differences and resistance to seismic loads and horizontal forces.
caissons

It is similar to the function of the piles that we presented previously, except that it is used in the case of greater weights and can be cast on site or be prefabricated and be sunk to depths of up to 100 meters. It is not preferable to use it in the case of deep deposits of soft mud.
What are the best foundations for building a house?

     Strong foundations for a house are very important in building a structure because the foundation is one of the most important parts of a building. If the foundation is strong and solid, it can only support the total load of the building.
     If the foundation of the structure is not designed properly and is not sufficient to support the load of the structure, then there is no point in investing money in the superstructure of the building.
     So it is very essential that you choose the best foundations for your home. Care must be taken that the foundations are built with strong building materials.
     The building materials used in constructing the foundations must also be tested. The material must pass all the rules provided by the local area code standards.
     The foundations and bases of a good house or building must be built of strong building materials so as to give maximum stability and structural balance to the building and to preserve the house during hurricanes and earthquakes.

What is the strongest foundation for a house?

The type of foundation suitable for building the structure depends on the type of soil available at the site and the type of building we have to construct. For light or temporary structure, shallow foundation is used while for tall buildings, deep foundation is used.