Civil Engineering/ETABS

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Expert: - 12/20/2006


Question
Dear Sirs,
I am a new user using ETABS Nonlinear v9.0.9 version for design of RCC buildings. I would like to few things mentioned below:

-  Application of Wind load as per BS: 6399 and use of rigid / semi rigid diaphragm

-  Application of Notional load.

-  Analysis & design of curved beams

-  I have modeled a 20 story building and adopted flat slab system which is modeled with a single shell element. However, on checking the reactions (for DL+LL) at the supports by ETABS and manual calculations I find lot of difference.

Waiting for the response.

Thanks & regards,
Astrid

Answer
Hi Astrid,

I am fairly new to ETABS too, but I can answer as follows:

1. Suggest you use semi-rigid diaphragm, as that will yield more accurate results.
2. Notional load is one of the options within the software, but if you use pdelta, then you do not need this in addition.
3. Curved beams, you will need to generate as a series of short straight sections.
4. Flat slab is not too well catered for ETABS- for that you can use SAFE. However, as for the manual check, you need to mesh the element to smaller size rather than using single elements.

There is a very good dicussion forum on CSI website where you can get a lot of help.

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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