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Civil Engineering/Slenderness of column


Salam sir. Hope you are doing fine. I just want to ask that I am designing a frame whose base is pinned and it has a fixed connection with Rafter(Beam) at the top while no bracing is provided at top to cater sidesway. What value of k must be used. Should we consider it as pinned at base and fixed at top or pinned at base and free at top. Please note that it has a fixed connection with beam at top but no bracing to resist lateral loads.

Hi Nouman,

Fist of all you need to consider slenderness of the column about both axes, and this is determined on the basis of the fixity conditions at both ends along both axes- so you need to work out the stiffness of the beams at the top, relative to the stiffness of the column. There are formulae in the relevant codes (especially for steel), or if you use ETABS that works it out automatically. I reckon in your case the factor will be between 1.0 and 2.0

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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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