The foundation is a supporting member of the structure which ultimately transfer loads from the Building’s walls or columns to the Earth. A foundation is the part of the building that is in direct contact with the ground. The main purpose of the foundation is to transfer all loads of the building to the earth.
The foundation basically holds the structure up so it will not sink in the supporting ground. Foundation holds the structure so it will not be blown away by strong winds like tornadoes. The foundation selection will also depend on the structural system and type of the structure. The life of the structure can never be more than the importance life of foundation.
The foundation of the structure must be safe against the four major eventuality:
- Sinking or settlement
- Differential settlement
The foundation systems are required to meet the following important requirements:-
01. The basic requirement for any structure regarding its load resisting capacity is that the structure shall be constructed in such a way that the combined dead loads, live loads, horizontal loads like earthquake and wind load can be resisted carried and transmitted to the ground safely without any structural damage, deflection and distortion.
02. Foundation should be taken sufficient in deep into the ground so that the structure is not affected by ground movement such as swelling. Shrinking, freezing. The landslide also should not affect the stability of the building. The structure should be safe against the damage and distress.
03. Foundation base should be rigid so that the differential settlement are minimised, especially in a case when superimposed loads are not evenly distributed over the foundation.
04. Foundation should also be so located that its performance is not affected due to any unexpected future influence like earthquake and overloading.
05. Foundations must be designed to resist the ultimate loading cases combination to resist both overturning and sliding.
06. Foundation should resist attack from chemicals in soil. Groundwater and soil may contain different types of chemicals which are harmful to the foundation concrete, the most aggressive of which are sulphates. Sulphate attack can usually be offset by using sulphate resisting cement, but even this will not be a perfect alternative to the problem unless sufficient care is taken in placing the concrete, by vibrating and curing.
07. Foundation should be taken deep enough to resist the overturning, though soil bearing capacity is good at sufficient depth. And also deep enough so as to be free from swelling and swelling.