What is a Foundation in Construction?
A foundation is an essential part of a building or civil structure as it bears the weight of the structure and transfers it safely to the soil. Foundations can be broadly classified into two types: shallow and deep foundations. A shallow foundation transmits the load to a stratum that is located at a shallow depth below the ground surface. On the other hand, a deep foundation transfers the load to a deeper stratum present at a considerable depth below the surface.
The choice of foundation type depends on various factors, including the height of the building and the strength of the soil on which it is to be built. In the case of tall buildings such as skyscrapers or structures built on weak soil, deep foundations are usually recommended. This is because deep foundations can provide the necessary support required to bear the weight of the structure and transfer the load to a deeper, more stable layer of soil.
Another important consideration while choosing the foundation type is the future expansion of the building. If the plan is to extend the building vertically in the future, then it becomes crucial to use a deep foundation to ensure the stability and safety of the structure. Thus, the selection of the appropriate foundation type is critical for the structural integrity and long-term stability of any building or civil structure.
Fig.1.Building Foundation in Construction
Constructing a foundation requires digging trenches into the soil until a hard stratum is reached. The trenches are then filled with concrete and reinforced with a steel cage to increase its strength. The protruding steel rods act as the foundation’s bones and must be connected to the substructure above. The materials used to construct the foundation, such as concrete, steel, stones, and bricks, depend on the design loads and the type of soil beneath it.
However, the construction of a foundation must also consider its effects on the environment. For instance, the excavation and piling works for deep foundations may disturb nearby soil and structural foundations, leading to settlement issues. Therefore, such effects must be studied and addressed before undertaking any operations. Additionally, waste materials generated during construction must be disposed of properly.
The design of a foundation must also account for its ability to resist external harm. Therefore, the foundation for each structure is designed to prevent the underlying soil from undergoing shear failure and limit any settlement caused during the first service load. The allowable bearing pressure is defined as the maximum pressure the soil can withstand without failing.
What is the Purpose of Foundation?
Foundations are essential for the stability of any load carrying structure. The strength of a structure is directly proportional to the strength of its foundation. Hence, it is crucial to ensure that the design and construction of foundations are carried out with utmost care.
The primary purpose of a foundation is to provide a stable and level surface for the substructure to be built upon. It acts as a firm base, which can withstand the weight of the structure and the loads that it carries. A well-designed foundation can prevent the lateral movements of the supporting material, ensuring that the structure remains stable over time.
Another important function of a foundation is to distribute the load of the structure evenly onto the surface of the bed. This even transfer of the load helps to prevent unequal settlement of the building, which can cause structural damage. Differential settlement is an undesirable building effect, which can lead to costly repairs and renovations in the future.
The foundation also serves to distribute the load of the structure over a large base area and onto the soil underneath. The load transferred to the soil should be within the allowable bearing capacity of the soil. This ensures that the structure remains stable and secure, even under heavy loads and adverse environmental conditions.
In summary, a well-designed foundation is crucial for the stability and safety of any load carrying structure. It provides a stable and level surface for the substructure to be built upon and distributes the load evenly onto the surface of the bed and the soil underneath. This helps to prevent differential settlement and ensures that the structure remains stable and secure over time.
Functions of Foundation in Construction
Foundations are an essential element of any construction project, serving a variety of purposes. One of the primary functions of a foundation is to provide overall lateral stability to the structure. This means that it prevents the building from collapsing or being damaged due to lateral forces, such as wind or earthquakes.
Another purpose of foundations is to provide a level surface for the construction of the substructure. By creating a stable and level base, foundations ensure that the rest of the building can be constructed correctly and safely. Additionally, foundations play a crucial role in load distribution. They help distribute the weight of the building evenly, ensuring that no one area is under more stress than another.
Foundations also serve to reduce the load intensity of the building to a level that is within the safe bearing capacity of the soil. This is important because soil can only support a certain amount of weight before it begins to sink or collapse. By reducing the load intensity, foundations prevent the building from putting too much pressure on the soil and causing damage.
Another essential function of foundations is to resist and prevent soil movement effects. This means that foundations are designed to withstand the movement of soil due to factors such as changes in temperature or moisture levels. By resisting soil movement, foundations ensure that the building remains stable and secure over time.
Finally, foundations can solve problems such as scouring and undermining. These issues can occur when soil is washed away or eroded, leaving the foundation exposed and vulnerable. By constructing a foundation, these problems can be prevented, ensuring that the building remains secure and stable for years to come.
Requirements of a Good Foundation
The design and construction of a well-performing foundation must adhere to certain fundamental requirements that cannot be overlooked. Firstly, the foundation should be designed and constructed in such a way that it can effectively sustain and transmit both the dead loads (permanent loads of the structure) and the imposed loads (temporary loads such as live loads) to the underlying soil without causing any settlement that may result in stability issues for the structure.
To avoid differential settlements, which occur when one part of the foundation settles more than another, it is essential to provide a rigid base for the foundation. This becomes particularly important in areas where the superimposed loads are not evenly distributed, as uneven settlement can lead to structural problems.
Depending on the characteristics of the soil and the local environmental conditions, it may be necessary to construct a deeper foundation to guard against potential damage or distress caused by issues such as shrinkage or swelling due to temperature changes. This is particularly relevant in areas where soil movement is more prominent.
Another critical consideration is the location of the foundation. It should be chosen in an area that will not be affected or influenced by any future works or factors that may impact its stability or performance. Careful site selection is crucial to ensure the long-term durability and reliability of the foundation.