Civil Engineering/Combined Footing

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Expert: - 9/9/2009


Question
Dear Arshad,
I am designing a foundation made up of a four beams connected together. size of beams 6.85m x 0.85m x 1.1mdeep. It has four point loads (119 kN) at the intersection of the beams (at 4 corners) and each beam also has a uniformly distributed load (21 kN/m) applied.
what is the best way to design such foundation and finding the max. bearing pressures, moments and shears.

Your help is very much appreciated

Kind Regards

Ayman

Answer
Hi Ayman,

You need to obtain the modulus of sub-grade reaction and use this to form the spring-stiffnesses for the foundation, which should be designed in 3-D (although you could do a simplified 2-D analysis, using just one side of the square, and applying only 59.5 kN at each end. Basically this is a problem of beam on elastic foundation (check this in your text-books or on Google).  

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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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