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excel spreadsheet for raft foundation design
#1

excel spreadsheet for raft foundation design

A raft foundation consists of a raft of reinforced concrete under the whole of a building. This type of foundation is described as a raft in the sense that the concrete raft is cast on the surface of the ground which supports it, as water does a raft, and the foundation is not fixed by foundations carried down into the subsoil.

Raft foundations may be used for buildings on compressible ground such as very soft clay, alluvial deposits and compressible fill material where strip, pad or pile foundations would not provide a stable foundation without excessive excavation. The reinforced concrete raft is designed to transmit the whole load of the building from the raft to the ground where the small spread loads will cause little if any appreciable settlement.
The two types of raft foundation commonly used are the flat raft and the wide toe raft.

The flat slab raft is of uniform thickness under the whole of the building and reinforced to spread the loads from the walls uniformly over the under surface to the ground. This type of raft may be used under small buildings such as bungalows and two storey houses where the comparatively small loads on foundations can be spread safely and economically under the rafts.

The concrete raft is reinforced top and bottom against both upward and downward bending. Vegetable top soil is removed and a blinding layer of concrete 50 mm thick is spread and levelled to provide a base on which to cast the concrete raft. A waterproof membrane is laid, on the dry concrete blinding, against moisture rising into the raft. The top and bottom reinforcement is supported and spaced preparatory to placing the concrete which is spread, consolidated and finished level.

When the reinforced concrete raft has dried and developed sufficient strength the walls are raised as illustrated in Fig. 12. The concrete raft is usually at least 150 mm thick.
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#2
If the loads transmitted by the columns in a structure are so heavy or the allowable soil pressure so small that individual footings would cover more than about one-half of the area, it may be better to provide a continuous footing under all columns and walls. Such a footing is called a raft or mat foundation. Raft foundations are also used to reduce the settlement of structures located above highly compressible deposits. Since rafts are usually at some depth in the ground, a large volume of excavation may be required. If weight of the excavated soil is equal to the weight of the structure and that of the raft, and the centres of gravity of excavation and structure coincide, settlement would be negligible. Where complete compensation is not feasible, a shallower raft may be accepted if the net increase in loads in small enough to lead to tolerable settlement.
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#3
The sub grade soil is considered as an infinite array of individual springs unaffected from the deformation of
others. The spring constant is the modulus of sub grade reaction. The following conditions are to be satisfied for this

value.

The rigid analysis gives relatively more conservative design of the raft against bending moment resulting in much bigger section. Hence, flexible design is preferable from the point of view the economy of structure. Analysis using this approach has been covered under the course on Soil-Structure Interaction.
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#4
Raft foundation is a thick concrete slab reinforced with steel which covers the entire contact area of the structure like a thick floor. Sometimes area covered by raft may be greater than the contact area depending on the bearing capacity of the soil underneath. The reinforcing bars runs normal to each other in both top and bottom layers of steel reinforcement.
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#5
To get full information or details of excel spreadsheet for raft foundation design please have a look on the pages

http://civilax.blogspot2014/04/design-of...ation.html

if you again feel trouble on excel spreadsheet for raft foundation design please reply in that page and ask specific fields in excel spreadsheet for raft foundation design
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#6
To get full information or details of excel spreadsheet for raft foundation design please have a look on the pages

https://scribddoc/135946168/RAFT-FOUNDATION-DESIGN

if you again feel trouble on excel spreadsheet for raft foundation design please reply in that page and ask specific fields in excel spreadsheet for raft foundation design
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#7
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#8
plz send me the design of raft foundation xcel sheet..its for my mtech thesis work
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#9
Please send me a spreadsheet for raft foundation design at [email protected]
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#10
Dear Sir,
I need the spreadsheet for raft foundation design
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