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Civil Engineering/HELICAL STAIR CASE

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Expert: - 6/3/2009


Question
Thanks in advance!   i have a helical stair case with 176^ total angle subtended by the helix the internal diameter of the stair 1.5m and the external diameter of the stair 3.0m in plan.The height of the room i s4.0m from ground floor to fist floor slab.
i have analyzed the stair with a REYNOLDS BOOK as a reference, my question is the forces at the helical stair vertical moment,torsional moment and with of the stair how to transfer to the supporting slab at first floor.


Answer
Hi Mulugheta,

Just design the section of stair that is in contact with the first floor slab as a wide beam, with the vertical moments, shear and torsion as determined by the analysis. If the section of stair can take all these internal forces within limits of the materials, then the floor slab (which is much wider, and presumably thicker) will also be able to resist the support reactions.

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Arshad Khan

Expertise

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.

Experience

Employment history: 36 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.

Organizations
.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)

Publications
•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

Education/Credentials
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 date)

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