The settlement of foundation needs to be contained within tolerable limit specified by applicable standards in order to prevent structural damage or dysfunction of the building. Moreover, the depth of foundation should be adequate to avoid the detrimental ground movements such as shrinking, swelling, and freezing. Additionally, it should have sufficient safety factors against forces that tend to overturn and/or slide the foundation structure.
Furthermore, due to the fact that it is in direct contact with soil, the foundation should be able to withstand attacks of aggressive agents in subsurface soil. Finally, the foundation basically holds the structure up so it would not sink in the supporting ground.
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| Fig. 1: Foundation of Multi Storey Building |
Foundation Design Requirements
- The foundation, including the underlying soil and rock, must be safe against a structural failure that could result in collapse. For example, the foundation for a skyscraper must support the great weight of the building above on a relatively narrow base without danger of overturning.
- During the life of the building, the foundation must not settle in such a way as to damage the structure or impair its function.
- It should be adequately rigid to minimize differential settlement specifically when superimposed loads are distributed unevenly.
- The foundation must be feasible, both technically and economically, and practical to build without adverse effects on surrounding property.
- The ability of foundation to safely support and transfer combined dead loads, live loads, horizontal loads such as wind and earthquake to subsurface soil in one of the most prime design requirements.
- The depth of foundation should be adequate so that it prevents overturning, and protects the building against damage or distress caused by swelling or shrinkage of the subsoil. Soil bearing capacity is good at sufficient depth.
- Foundation structure should be designed in such as way that possess enough safety against exceptional future loads for example earthquake and overloading.
- It should resist attack from chemicals in soil. Various harmful materials like sulfates may be present in groundwater and soil that deteriorate concrete foundation. Sulphate attack can usually be offset by using sulphate resisting cement, but even this would not be a perfect alternative to the problem unless sufficient care is taken in placing the concrete, by vibrating and curing.
