Category: Foundations

The definition and functions of foundation have been given in chapter 6. In this chapter broad guidelines for fixing the dimensions of foundation are given and different types of foundations are explained.

Category: Foundations Foundations in Black Cotton Soil

Black cotton soil swells during rainy season and cracks in summer due to shrinkage. These shrinkage cracks are 100 mm to 150 mm wide and 0.5 m to 2 m deep. Swelling creates upwards pressure on the structure and shrinkage creates downward pull. It results into cracks in foundations wall and roof. Hence foundation in black cotton soil need special

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Category: Foundations Pile Foundations

These foundations are known as deep foundations. A pile is a slender column made of wood, concrete or steel. A pile is either driven into the soil or formed in situ by excavating a hole and then filling it with concrete. A group of piles are driven to the required depth and are capped with R.C.C. slab, over which super

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Category: Foundations Arch Foundation

Inverted arch foundations are provided in the places where the SBC of the soil is very poor and the load of the structure is through walls. In such cases inverted arches are constructed between the walls. End walls should be sufficiently thick and strong to withstand the outward horizontal thrust due to arch action. The outer walls may be provided with buttress walls

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Category: Foundations Grillage Footing

High rise buildings are built with steel columns encased in concrete. Such columns carry very heavy load and hence they need special foundations to spread the load to a larger area of soil. Grillage foundation is one such special foundation. It consists of one tier or more tiers of I-sections steel beams. Figure 7.7 shows a typical two tier grillage

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Category: Foundations R.C.C. Footings

There are mainly two types of R.C.C. footings: 1. One way reinforced footings. 2. Two way reinforced footings. 1. One Way Reinforced Footing: These footings are for the walls. In these footings main reinforcements are in the transverse direction of wall. In longitudinal directions there will be only nominal reinforcement. 2. Two Way Reinforced Footings: For columns two way reinforced

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Category: Foundations Conventional Spread Footings

This type of foundations are commonly used for walls and masonry columns. These foundations are built after opening the trenches to required depth. Such footings are economical up to a maximum depth of 3 m. As these foundations are suitable depth, they are grouped under shallow foundations. Figure 7.1 shows a conventional spread footing for a wall and Fig. 7.2

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Category: Foundations Dimensions of Foundation

Guidelines for minimum dimensions are given below: (a) Depth of Foundation: For all types of foundations minimum depth required is calculated using Rankine’s Formula: where p = safe bearing capacity of soil w = unit weight of soil ϕ = angle of repose of soil. However in any case it is not less than 0.9 m. Finding safe bearing of the

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