Civil Engineering/Load bearing

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Expert: - 5/27/2002


Question
Hello, this may be a long shot but I wonder if you can help.  I'm trying to find out if there's a relatively simple way of assessing the load bearing capabilites of say the substrate of a beach, e.g sand /shingle etc?

Answer
Hi Conor,

Yes, you can either get a proper in-situ plate bearing test carried out by a suitable laboratory, or you can improvise and do your own test as follows:

1. Dig down to the strata that you wish to put a foundation on, say a 50X50 cm pit, as deep as you reach firm ground.
2. Carefully dig out a 5X5 cm hole, say about 2-3 cm deep, with an even bottom surface.
3. Place a 5X5 cm timber post (say 50 cm long) vertically into this, lightly tap it down with a mallet, and mark it against another nearby solid object so that you can measure settlement.
4. Now load this post from above, and monitor its settlement with increasing loads.

Basically if you have put on say 20kg load, this translates to 20/0.05X0.05= 8000 kg/m2 capacity, which is about 78 kN/m2. This is not a lot, as compacted sand should be able to support well over 200 kN/m2 without much settlement.

Of course if you want to do a thorough job, you need to monitor settlement over a period of a few days, and also with variables such as ground water table (tides?), etc., and if possible use a bigger footprint of post, like 10X10 cm. the bigger, the more reliable the results, but you need very heavy loads then. Remember too that nearby trees affect foundations during the different seasons.

Hope all that helps!

Kind regards,

Arshad.  

Civil Engineering

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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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