Selection of type of foundation is very important as eventually, it could lead to many issues if we do not construct the wrong foundation.
Foundation is the structural element that transfers the loads from the superstructure safely to the ground without any excessive settlement, differential settlement, or damage to the superstructure or foundation itself.
Types of loads applied on the foundation.
- Dead Loads or the self-weight of the structure
- Imposed Loads those loads applied actions
- Lateral loads such as wind loads, earthquake loads, earth pressure loads, etc.
Thus, mainly there are two types of loads
- Vertical loads
- Horizontal Loads
Foundation shall be designed to withstand these loads. Therefore, consideration of the nature of the loads are very important.
Apart form that the condition of the ground shall be assessed correctly to determine the foundation type.
Selection of the foundations could be made based on the following criteria.
- It is required to do a soil investigation-based type of construction that we are anticipating. The nature of the soil investigation will depend on the condition of sub surface condition and information gathered from the site.
- Firstly, we need to calculate the loads on the foundation.
- Generally, the soil investigation report provides the most suitable type of foundation to be constructed for the particular structure. Or it will provide several types of foundations if applicable.
- For small to medium scale buildings, we can used shallow foundations if there are no very weak ground conditions such as having peat soil the land.
- When the column load increases, the size of the shallow foundations will be increasing. Beyond some point, there will overlapping of the pressure bulbs of individual foundation. In those situations, we have to change the type of foundation. We may construct raft foundations or deep foundations as applicable.
- We could construct raft foundation for building up to 10 stories. The number of stories depends on the soil allowable bearing capacity.
- For medium story buildings we also can adopt the precast piles driven into the hard solid layer when we cannot construct the structure on the shallow foundation.
- It will be required to construct pile foundations when we construct high rise buildings.
