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Expert: - 3/31/2009


Question
On existing 20cm ground floor slab with y8@20c/c steel mesh a 90 ton machine 3.5x5.0m base dimensions is placed.The ground slab is placed directly on compacted soil.
i want to ask if this slab can resist the machine?

Answer
Hi Mulugheta,

If the ground is very well compacted so that it does not settle with a pressure of 50 kN/m2, then this should be OK (assuming that the machine spreads the load evenly over the footprint, and not via concentrated loads at corners, etc).

However, if there is some settlement, then you could expect some cracks outside the perimeter of the footprint. For this sort of load I would have designed a 300mm thick slab just under the machine, with an isolation joint around to allow for differential settlement.

If the machinery operates with much vibration, your problem of settlement becomes worse!  

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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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