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Civil Engineering/Flat slab detailing & punching shear

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Expert: - 12/21/2011


Question
Hello Sir,
I have two questions regarding flat slab :
1.In the preparation of drawing for flat slab, i use mesh at top and bottom to all panels and then apply additional bars around the columns(that will resist punching& moment) and along the span(for moment) according to the design result.Is this procedure correct? I would like if you give me one example of flat slab detailing drawing that can be used in the practical world.
2.I check punching shear for flat slab using hand calculation eventhough i use SAFE. I take only reaction of columns from SAFE but i do not use Mx & My...is it correct ?
Thanks

Answer
Hi Meda,

1. Yes, this is acceptable, so long as you ensure proper lap between mesh and additional rebar. You can get some further details from this website:

www.rds.com.vn/uploads/Flat_Slab_Design.pdf

2. No, you need to take the column reaction and increase the applied punching shear due to the effects of the moments of the column strips at the column in question. Refer to clause 4.2.5.2 of BS8110. Page 51 of the PDF from the above website also gives details of the additional shear due to slab bending moments.  

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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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