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Civil Engineering/Supports under Raft(Etabs)

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Expert: - 11/7/2009


Question
Dear Sir,
I hope that you are fine and keeping good !
I was reading an etabs design manual of Atkins and it was written   that for rafts and piles pin or spring support should be used in modell.. I always use fix support for rafts and looks justified to me.. can you please explain why should we use pinned support ????\
I shall be grateful

Regards,


Answer
Hi Muhammad,

If you have access to the Atkins Stroogle website, you will see the full arguments there for and against fixed supports. For any building more than a few storeys high, it makes little difference as to whether you use fixed or pinned supports. However, for a single or double-storey building, sometimes you can get unrealistic local bending moments at the bases of walls if the supports are modelled as fixed, so in this case pinned will be better.

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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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