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Civil Engineering/INSITU- RC STRUCTURE


QUESTION: Dear sir

In insitu RC structure is it possible to make column beam junction behave as pin joint by detailing R/F



ANSWER: Hi Priyantha,

Yes, but not as a 10% free hinge, unless you cast the column separately from the beam and provide some sort of flexible pad. You can achieve up to 80-90% hinge/pin action by detailing rebar in such a way that hogging moment transfer is minimised.

---------- FOLLOW-UP ----------

QUESTION: Dear sir
1. Can you simply explain the basic detailing rules so that beam column junction to behave as pin joint in intermediate column and end column.

2. in a particular RC frame beams were analysed as simply supported at the column beam junctions and supposed to detail them as pin joints.(R/F to be provided according to the above analysis.)

Is it correct to design columns associated with this frame only for axial loads or is there any percentage of moment according to relative stiffness es

Hi Priyantha,

1. Either have very nominal rebar going through from column into the beam, or else detail the column vertical rebar to cross over eachother to form an X (refer to details in the Reynolds manual for RC structures).

2. As I mentioned earlier, a 100% pin joint is very difficult to achieve, so I would allow at least 10- 15% of beams moments to be transferred to columns.

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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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