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Civil Engineering/Expansion joint in huge water concrete tank

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Expert: - 2/16/2010


Question
Do we need expansion joints in walls or base slab for an RC above ground water tank of internal dimensions of 20mx19mx12m height with wall thickness of 1.5 m at the bottom and 0.50m at the top. Base slab thickness is 1.3m & there is internal wall/partion of 1.5m thk. in the middle of the 19m direction.
the structure is in saudi arabia.
Please if there is some photos for the similar case, please attache...

Thanks & Best Regards

Engr. Amer

Answer
Hi Amer,

No, if the walls and slabs are designed properly for early-age shrinkage cracking, then you do not need any joints in these. However (if I may say so), based on my experience of designing many tanks, I feel that the wall thickness appears excessive.

For a tank of this proportions, the walls will not behave as pure cantilevers, but will have some 2-way spanning for the botton 6-8 meters. That way you can achieve great economy in the rebar and also reduce the wall thickness to 0.3m at the top and probably around 1.0m at the bottom.

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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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