How deep is the foundation of a 4 story building?

As per thumb rule, minimum depth of foundation is 1 metre (3.5 feet) is acceptable for one storey building in medium clay soil, 4 feet (1.2m) depth for 2 story, 5 feet (1.5m) depth for 3 story, 6 feet (1.8m) depth for 4 story and 7 feet (2.1m) depth for 5 story building.

How big can a raft foundation be?

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.

How do you calculate raft foundation?

A = total area of the raft. = eccentricities about the principal axis passing through the centroid of the section. = moment of inertia about the principal axis through the centroid of the section. = eccentricities in x and y direction of the load from the centroid.

Which foundation is best for 5 storey building?

Shallow foundation will be best foundation for building with more storeys. Pile foundation is also recommended for G+5 buildings.

What are the disadvantages of raft foundation?

Disadvantages of Raft Foundation

• Raft foundation is prone to edge erosion.
• Raft foundation requires more amount of reinforcement in some cases, and it will ultimately cost more.
• Skilled labours are required as compared to other foundation.

Is a raft foundation expensive?

Raft foundations are relatively inexpensive and fast to put down, when compared with other types of foundation. Ground excavations are less onerous than for trench excavations, for example, and the foundation and floor slab can often be combined, giving significant savings on materials and time.

What is the minimum reinforcement in raft foundation?

2.1 Min reinforcement shall be 0.15% of total cross-sectional area for mild steel bars and 0.12% of total cross-sectional area for HYSD bars.

Are raft foundations expensive?

Which soil is suitable for raft foundation?

Usually clay has a higher moisture content and when the moisture content becomes stable upto certain depth it becomes suitable for the substructure. Raft foundation is preferred when the clayey soil is compact and hard.

Which type of foundation is normally used for multi storey building?

Pier Foundation
Pier Foundation Pier is an underground structure that transmits a more massive load, which cannot be carried by shallow foundations. It is usually shallower than piles. The pier foundation is generally utilized in multi-story structures.

Which foundation is used for multi storey building?

And also pile foundations are used when a building has very heavy, concentrated loads, such as in a high rise structure, bridge, or water tank [3]. Pile foundations are able to take higher loads than spread footings.

What is the height of a 4 story building?

Also under the current standard, a 4 story building can be at most 62 feet or an average of 15.5 feet per story.

Are raft foundations good?

Other reasons that make raft foundations preferable to footings are due to their engineering benefits. They are ideal for poor ground condition where normal footings would not cope well as they cannot spread the load as effectively.

What is the cheapest foundation to build?

concrete slab
If you’re building a home, a concrete slab makes sense because of its low cost. It’s the cheapest option available, and, comparatively speaking, it’s the quickest solution. The right crew can lay a concrete slab foundation in a short period of time, and the drying process doesn’t take much longer.

Which is better pile or raft foundation?

Pile foundations can help transfer loads through weak, compressible strata or water onto stronger, more compact, less compressible and stiffer soil or rock at depth. The addition of piles to a raft increases the effective size of a foundation and can help resist horizontal loads.

How do you calculate reinforcement in raft foundations?

3 deflection calculation: The maximum deflection is considered as the deflection of three span continuous beams under uniform load, the calculation formula is as follows: ν max =（0.677q 1 +0.990q 2 ）l 4 /100EI; Standard value of static load q 1 = 1.800+1.500=3.300kN/m; Standard value of live load q 2 =2.700kN/m; the …

Where is raft foundation applicable?

Usually, mat foundation is spread over the entire area of the structure it is supporting. 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.