How do you calculate raft foundation?
The maximum settlement should generally be limited to the following values: Raft foundation on clay – 65 to 100 mm. Raft foundation on sand – 40 to 65 mm.
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2) Soil line Method (Elastic Method) of Raft Foundation Design.
Soil Characteristics | K_{s}(Kg/cm^{2}) | |
---|---|---|
1. Stiff | 1 to <2 | 2.7 |
1. Very Stiff | 2 to <4 | 5.4 |
3. Hard | 4 and over | 10.8 |
How do you underpin a raft foundation?
Traditional underpinning involves excavating adjacent to the existing foundation, undermining to suitable bearing ground and then concreting in sections to provide new foundation. Alternatively if ground conditions dictate, a combination of Piling with Needle beams can be installed from the outside of the building.
What is cellular raft foundation?
Raft foundations are a type of shallow foundation. … A cellular raft foundation consists of two slabs with two-way interlocking ground beams. The upper (suspended) slab and the lower (ground-bearing) slab are usually incorporated within the beams to form I-sections, with voids between them.
Is raft a code for foundation?
IS : 2809-1972· shall apply. 3.1 For satisfactory design and construction of a raft foundation.
How do you calculate the thickness of concrete?
How to calculate concrete:
- Determine how thick you want the concrete.
- Measure the length and width that you’d like to cover.
- Multiply the length by the width to determine square footage.
- Convert the thickness from inches to feet.
- Multiply the thickness in feet by the square footage to determine cubic feet.
How do you determine the thickness of a footing?
How to Calculate Footing Size
- Determine the width and length of the cement slab in inches.
- Divide the width by 12 to convert it to feet. …
- Divide the length by 12 to convert it to feet. …
- Determine the depth or thickness that is required for the footing in inches. …
- Multiply the width by the length and then by the depth.
What type of soil is suitable for raft foundation?
Raft foundation is preferred when the clayey soil is compact and hard. Even strap foundation can also be used. Soft clayey sand is prone to expansion and shrinkage. They have a low bearing capacity and are unsuitable for footing and strap foundation.