How do you calculate raft foundation design?
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How do you calculate raft foundation design?
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….2) Soil line Method (Elastic Method) of Raft Foundation Design.
| Soil Characteristics | Ks(Kg/cm2) | |
|---|---|---|
| 1. Stiff | 1 to <2 | 2.7 |
| 1. Very Stiff | 2 to <4 | 5.4 |
| 3. Hard | 4 and over | 10.8 |
Do shear walls have foundations?
Shear walls that are designed to resist seismic loads require significantly larger foundations than in the case of wind loading as the dominant lateral load condition, depending on the height of the building and the number of shear walls in the building.
What is a raft foundation design?
A raft foundation is a reinforced concrete slab under the whole of a building or extension, ‘floating’ on the ground as a raft floats on water. This type of foundation spreads the load of the building over a larger area than other foundations, lowering the pressure on the ground.
What is the minimum thickness of raft foundation?
The minimum thickness of raft foundation is 300mm.
How do you size a raft foundation?
The dimensions of the raft should be at least 3m x 2m and the longer dimension should be less than 1.5 times the shorter dimension. Internal stiffening beams, similar to the internal edge beam may be required 6. The ground must be well consolidated and capable of supporting a load of at least 50kN/m². 7.
How do you build a raft foundation?
Construction Process of Raft foundation
- Identify the desired depth at which foundation is to be provided.
- Excavate soil up to the required depth.
- Compact the soil.
- Provide a waterproofing membrane.
- Pour 3” of plane cement-sand paste.
- Lay reinforcement maintaining the required spacing using spacers.
Where should shear walls be placed?
Structurally, the best position for the shear walls is in the center of each half of the building. This is rarely practical, since it also utilizes the space a lot, so they are positioned at the ends. It is better to use walls with no openings in them. So, usually, the walls around lift shafts and stairwells are used.
What is the difference between shear wall and core wall?
Shear wall and core wall both are similar. Shear wall is considered as a linear wall which is provided at the edges of buildings. Core wall is provided at the center of the building. The variation of results can be seen core wall in the middle has less deformation compared to other models.
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.
Where is raft foundation applicable?
Raft foundation is generally used to support structures like residential or commercial buildings where soil condition is poor, storage tanks, silos, foundations for heavy industrial equipment etc.
How do you figure concrete for a raft foundation?
Calculation of volume of concrete for the column:
- Volume of Concrete = 0.6×0.4×3= 0.72m3
- Volume of Circular column = πr2 x 3 = 3.14 x 0.252 x3 = 0.58m3
- Volume of concrete = 1.2x1x0.1 = 0.12m3 Total volume of concrete required for footing= 0.32+0.12=0.44m3