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Civil Engineering/ribbed slab in ETABS

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Expert: - 5/8/2011


Question
hello,

I am working on my final year project. but i have a problem in modelling a one way ribbed slab in ETABS. I tried to define the slab as deck, but i got unreasonable values. The total depth of my slab is 0.5 m and the thickness of the slab is 0.1 m. I want to place this slab in one part of the floor where i hav long spans. The remaining is a normal solid slab..

please help me:)

Answer
Hi Demo,

The best way to model this is to define it as a membrane, with special one-way spanning, and then give it the following properties:

Overall membrane thickness should be the equivalent thickness by adding in the 100mm flange and the ribs, averaged out per m2. That way, the slab self weight will be accurately captured.

The bending thickness can be reduced to 100mm, or else you can use the property modifiers to reduce the bending and shear capacities by appropriate factors.

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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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