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Expert: - 1/18/2010


Question
respected sir this is my first mail to you.
i wants to know that while fixing the dimension of coloumns & beams what propotion we have to take  

Answer
Hi Suhail,

You have not mentioned whether this is for steel or RC structures. The latter is more complicated, so I will address that.

The minimum sizes of columns and beams are determined by various factors, such as durability, fire-resistance, spans, support conditions, slenderness, loading, etc. If you use normal aggregate and need about 30-40mm cover to rebar, then for practical reasons, the minimum width/size of beams and columns should be between 175mm and 200mm respectively- otherwise there will be too much rebar congestion and concrete will be difficult to compact.

The next thing to determine is size for deflection and stresses, for which you can follow span/depth recommendations in local standards. This applies to both RC and steel beams. For example, for a simply supported RC beam the span/effective depth ratio should be about 12 to 14 and for continuous beams about 15 to 17.  

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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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