Raft Footing Design as per Eurocode

A raft foundation, also called a mat foundation, is essentially a continuous slab resting on the soil that extends over the entire footprint of the building, thereby supporting the building and transferring its weight to the ground.

A raft foundation is often used when the soil is weak, as it distributes the weight of the building over the entire area of the building, and not over smaller zones (like individual footings) or at individual points (like pile foundations). This reduces the stress on the soil.

The concept of stress is very basic to civil engineering. Stress is simply weight divided by area. For example, if a building measuring 5 x 5 weighs 50 tons, and has a raft foundation, then the stress on the soil is weight / area = 50/25 = 2 tons per square meter.

If the same building were supported by say 4 individual footings, each of 1 x 1m, then the total area of the foundation would be 4 m2, and the stress on the soil would be 50/16, which is about 12.5 tons per square meter. So increasing the total area of the foundation can dramatically lower the stress on the soil, which is nothing but weight per square meter.

A raft foundation is also very good for basements. Foundations are created by excavating soil in order to find strong, compact, undisturbed natural soil that is at least a few feet below ground level. This soil is much stronger than the loose soil at the surface. If we construct a raft foundation at say 10 feet below ground, and build concrete walls around the periphery, this makes an excellent basement. Therefore, an engineer designing a building with a basement will tend to choose a raft foundation over other types of foundations.

Details

Title	Raft Footing Design as per Eurocode
Duration	28 Mins
Language	English
Format	MP4
Size	79 MB
Download Method	Direct Download
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