Civil Engineering/Silo Foundation

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Expert: - 3/28/2009


Question
QUESTION: Dear Sir,
I want suitable foundation type for 5 silos of diameter 25m which are constructing in one line. Soil strata is very hard granular material and no ground water.

Regards
Prasad

ANSWER: Hi Prasad,

Assumong that these are cylidrical silos, then the most economical foundation is normally a strip footing directly below the cylindrical wall of each silo, and keep each foundation separate from the next silos foundation.

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QUESTION: Thank u very much for u r response.
Sir, silos are constructing side by side in one line so is there any chance for excessive settlements due to overlapping pressure bulbs.what should be minimum distance between each silo.

Reagrds
Prasad


ANSWER: Hi Prasad,

That's a good point, but this really depends on what the safe bearing capacity of the soil is and what the imposed pressure is. If the imposed pressure is close to the limit then I would say that a spacing of half to one diamater between each silo would be about right.

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QUESTION: thank u very much for u r quick response.As per u r suggestions i will try to calculate bearing capacity of strip footing (ring foundation) and compare with imposed pressure.can u plz guide me reagrding design of slabs on grade,which we design inside the ring foundation.  

Answer
Hi Prasad,

This would be considered a structural slab on grade, and the design needs to take account of the compaction and nature of the sub-grade and sub-base. Normally heavily loaded industrial floors would be between 200-300mm thick. For a silo, this may be even thicker. The following article gives further info:

http://www.structuremag.org/article.aspx?articleID=474  

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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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