Civil Engineering/Foundation type

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Expert: - 2/16/2011


Question
QUESTION: What is the best type of foundation for a foundation a bungalow built close to the sea?
Will a raft foundation be suitable? What type of a raft foundation will be suitable, if so?
Thank you

ANSWER: Hi 1234 (??),

That all depends on what the ground conditions are like. If there is competent rock near the surface you will waste resources and money by building a raft, when simple isolated footings or a strip footing will be fine.

If the ground is weak or likely to get eroded or likely to have differential settlement, only then could you justify using a raft.

If you want more details of raft footings, please browse my past answers.


---------- FOLLOW-UP ----------

QUESTION: Thank you very much for the help.
The ground is weak, the soil has low bearing capacity.
Could you please explain to me the meaning of deferential settlement and how it can be reduced by using a raft foundation?
Thank you.

Answer
In that case a raft foundation is best as it minimises overall applied pressures and also reduces differential settlement between one part of the building and the rest- if you have isolated footings, one could settle more than the other and this causes cracking in the beams and walls above.

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Arshad Khan

Expertise

I can answer any questions to do with civil and structural engineering consultancy and construction industry in East Africa and the Middle East, and specifically with the analysis and design of reinforced concrete structures. My particular expertise is in the aseismic design and optimisation of tall buildings.

Experience

Employment history: 36 years in Construction and consultancy in the UK, Kenya, Tanzania, Uganda, Ethiopia, Eritrea, South Africa, Somalia, Zambia, Austria, Bahrain, Kuwait, Doha and the U.A.E.

Organizations
.Fellow of Institution of Structural Engineers (UK) .Fellow of Institution of Civil Engineers(UK) .Member of the Institution of Engineers, Kenya .Registered Engineer, ERB, Kenya .Member of the Architectural Association of Kenya (Engineers Chapter) .Chartered Engineer (UK)

Publications
•1984: International Conference on the Art and Practice of Structural Design, London •1994: 3rd Int. Kerensky Conference in Structural Engineering, Singapore •2008: International Conference on High-Rise Towers, Abu Dhabi

Education/Credentials
BSc, 1st Class Hons, in Building Engineering, University of Bath, UK MSc in Concrete Structures and Technology, University of London. Diploma of Imperial College, UK.

Awards and Honors
•Science Congress Special Award (for 2-seater Hovercraft - 1968) •Institution of Civil Engineers Award for outstanding performance at Bath University (1975) •Concrete Society Postgraduate study Bursary Award (1976) •Consular Representative for British High Commission, Nairobi. (1995 to 1998) •Examiner for Institution of Civil Engineers Professional Interviews, Nairobi. (1997 to 1998) •Branch Representative in Vienna for PI assessment for Inst. of Struct. Engrs. (1999 to date)

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