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Civil Engineering/FLAT AND SOLID SLAB


Hello Mr  Arshad Khan
I hope u r fine , nice day for you and thanx you very much .

when i studied etabs i found :
- In the case of the solid slab choose the membrane of the slab .
- In the case of flat slab choose the plate or shell.
and I found that the option membrane in solid slab  matches  manual analysis of the beams actually .

first : please correct if I have any mistake in what i wrote above .
My  question is : If we have a flat slab with surrounding  beams and some of the interior beams , in this case what do we consider it?  flat or solid - that means plate or membrane  ? becouse I have found a big difference between the two cases  in the reactions of the columns & In the analysis of the beams .

Hi Hassan,

If you do not have downstand (stiffer) beams to support the slab, then that must be analysed as a flat slab, with sufficient widths for the the column strips and middle strips as per guidelines in codes.

In this case you must assign the slab as Shell, not membrane.

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Arshad Khan


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.


Employment history: 40 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.

.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)

•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 •2013: IEK International Conference, Kisumu, Kenya

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 2010)

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