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Civil Engineering/Tank foundation on piles

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Expert: - 2/8/2012


Question
Dear Sir,
I have a steel water tank to be checked.The diameter of the tank is 12m & having a total weight of 1200 ton.I want to use 22 nos of pile of 42m length with a capacity of 120 ton.From the pile cap a ring beam(12m c/c) of 500mm height & 750mm width is used to support the tank.
1.Please explain me the procedure of designing the pile cap and the ring beam.
  please give me some reference also.
         With best regards

Answer
Hi Barek,

I am assuming that the base of the tank is self-supporting, i.e. all the 1200 tonnes will be distributed equally around the perimeter, which is 3.142x12= 37.7m long. So, if you have 22 piles (which should be placed directly below the tank walls), then the span of the pile cap/ring beam will be 37.7/22 = 1.714m. There is no need to have a ring-beam on top of pile caps- combine that into one structure and deepen the ring beam if shear is a problem.

Just design the ring beam as a continuous beam (500 x 700) with supports at 1.714m centers and design for bending and shear. You may need to add additional vertical loading due to overturning caused by wind/earthquake action on the tank?

All this is based on first principles- I do not have a ready reference for it.  

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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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