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Civil Engineering/Torsional Capacity of Channels



I have a c lipped channel. I request you to kindly guide me how to calculate the torsional capacity of this type of section so that I can check whether applied torsion is within safe limits.

ANSWER: Hi Muzaffer,

This depends on various factors, including the distance between lateral/torsional supports. Please refer to the formulae here:

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QUESTION: Dear sir
I tried to understand the use of the formulas there but couldn't understand.
The c channel will be fixed as a cantilever of span 1 m and the torsion is due to point moment applied on this channel.. I would be extremely thankful for your kind guidence. I just want to calculate the allowable torsion on this channel.

Hi Muzaffer,

OK, try this one- it has better guidelines. As it says, you need to know the section properties, which are usually listed in books or manufacturers brochures.

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Arshad Khan


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.


Employment history: 40 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.

.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)

•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 •2013: IEK International Conference, Kisumu, Kenya

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 2010)

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