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Civil Engineering/Diaphragm shear transfer in concrete slabs

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Expert: - 4/5/2009


Question
Dear Arshad,
Once again, thank you so much for your reply (May 20, 2008). However, I would like to add to my earlier question that how would you check shear stress (speaking strictly for Shear Wall & Flat Slab cast-in-place cases)? Is it v = V / b*d as we do for beams? If yes, what would you take as "d" in a slab where the force is in-plane. And finally, would you add additional hook bars from flat slab into shear walls along the edges (say Shear wall is in North-South direction, and you are analyzing seismic forces in North-South direction.) I would like to thank you in advance, your reply is much appreciated.


Answer
Hi Adam,

Firstly the shear that the diaphragm resists is the difference between the storey shear that the shear wall takes and the sum of the storey shears taken by the columns at that floor. So, having got this net shear force resisted by the slab, you can design it as you said like a beam and to be on the conservative side take "d" as length of the shear wall where the slab connects to it in the N-S direction.

And, yes, it is a good idea to incorporate hooked bars into the shear wall.

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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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