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Expert: - 2/4/2005


Question
Dear Mr Khan,

 I hope that you can help me with this!  I am designing a small rural clinic as part of a project and it is in a seismic area in Peru.  I am designing with a RC frame.  Having calculated required floorslabs (largest span only), beam (largest span only) and columns (with largest load)for dead and live loads by hand, I want to put this into Strand7 to model seismic activity.  How do I come up with all these figures (modulus and shear modulus etc etc) that I need for the RC slab/beam?  That is to say for the total beam of concrete and steel, and not the parts independantly, as I can only enter the value for the whole beam and not add reinforcement with seperate figures to a concrete beam.

Secondly, am I going about this the right way?  Firstly designing for max spans by hand and then putting these beam/column/slabs designs into a program and checking with different loads.  In this case, how do I know the maximum permitted moment for each element?  

Thankyou very much in advance.

Mike

Answer
Hi Mike,

This is difficult to explain properly through this medium, but in general all software work like this:

1. Model the slabs as elements/plates and input the thickness.
2. Model the beams as depthXwidth (full depth, including slab part). Or you can model it as a T, including slab contribution.
3. No need to model rebar- it has minimal effect on stiffness.
4. Your approach is correct- work out sizes by hand, do the analysis and then check whether the chosen sizes yield reasonable amounts of rebar. If rebar is too much (%age), then you need to increase the member sizes.

I am not familiar with Strand;I use STAAD and if you visit this website it has a wealth of info in the knowledge
base, demos, etc.

http://www.reiworld.com/

Hope this 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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