Civil Engineering/roof truss


QUESTION: Dear sir

When normal roof truss analysis (triangular shape)what should be the end conditions. If both ends were fixed is it wrong

ANSWER: Hi Priyantha,

Truss joints are usually pinned (so that only axial forces are incurred in the members)but there is normally some fixity due to connection practicality. If the members are slender compared with the depth of the truss this is not a problem. If the sections are relatively thick, you may need o look at local bending stresses within the members near the joints.

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

QUESTION: Dear sir

In case of truss one side of it should rest on roller support and other pined. Can u explain why

What is more closer to pin joint welded joint or bolted joint

Hi Priyantha,

1. Mainly so that when the truss deflects or expands/contracts due to temperature variations, one end can slide to avoid additional stresses in the members.

2. Bolted connections would allow a bit of movement (unless HSFG bolts are used), so they are better than welds if you need to avoid secondary stresses in members at the joints.

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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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