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# Civil Engineering/structural design

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Question
Good day Sir.
I have 2 questions sir
1. how do i compute the self weight of a roof {both steel and timbre}
2. how do i design for hidden beams and what is the minimum dimension for hidden beams

Answer
Hi Saif,

1. Calculate the total surface area of the steel sheets and multiply by its unit weoght/m2, or by its thickness times 75 kN/m3. For the timber work out the total lengths times the cross-sectional area to get volume in m3 and multiply by 7 kN/m3 to get weight in kN, or by 700 to get weight in kg.

2.Hidden beams can either be column strips within 2-way spanning flat slabs (so size is determined by spans between columns) or they can be between one-way spanning ribbed slabs or hollow-pot slabs, and again the depth and width depends on spans- refer to guidelines given in relevant codes such as BS 8110.

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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: 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.

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 •2013: IEK International Conference, Kisumu, Kenya

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 2010)

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