Civil Engineering/CRACKED SECTION


whenever tension occurs it is likely that cracking of the concrete will take place.As there is good reinforcement bond those cracks are restrained from opening.

my problem is is there any connection between moment redistribution and those crack width. is it not suitable to do moment redistribution in structures in severe weather condition (like closer to sea)

ANSWER: Hi Priyantha,

Yes, moment re-distribution will increase cracks widths at supports, so you need to restrict the %age redistribution according to code guidelines on type of structure, rebar confugaration, etc.

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Can you pl explain why this happen . how crack width increase with moment redistribution

Because when you distribute moment from supports to span, the beam deflection increases, hence vertical curvature increases, hence rotation at support increases, leading to wider cracks at the top. For the same UDL on a beam, compare the calculated deflection at mid-span for a simply supported beam and a continuous beam, and you will see the 2 extreme values for mid-span deflections.  

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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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