Civil Engineering/Crank


QUESTION: what is a crank, pertaining to beam, slab & column construction, types of crank & how to determine the length of a crank

ANSWER: Hi Diana,

A crank is a sideways shift of two sides of a rebar by having a sloping section between the two sections. The crank dimensions are usually given as length and sideways shift, which is usually the same as the diameter of the bar. The intention is to use this for lapping rebar in columns and beams so that the overall sectional dimension of the member remains the same, apart from where the crank is. The crank slope is usually 1:10

Cranks are usually not used in slabs as the rebar at laps is placed horizontally adjacent, rather than forming a crank.

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QUESTION: Could you plz tell me the types of cranks if there are indeed types .. Bcuz m not sure if there are types thx

Hi Diana,

Visit thsi website and download the shape codes PDF:

Code 27 is the normal crank for lapping rebar in columns and beams, whilst 34 and 46 could also be considered part cranks and part other shape!

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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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