Civil Engineering/lateral buckling


please enlighten for the query.
Consider the axes x in horizontal , Y in vertical direction and Z normal to the plane Xy , Now if there is a Moment My , Bending Taking place along the horizontal axis (lateral bending) for a concrete beam. I know that for structural steel lateral bending is possible if the Compression flange is not Restrained . But i see that software output shows My moment which bends the beam Laterally. Can you Explain
1. if this bending laterally due To Moment My be called Lateral buckling of the Concrete beam just like there is lateral torsional buckling of steel beams.
2. Also explain for which Type of loads/cases/situations This Moment is possible for concrete beams.

Hi Arsalan,

1. No, the lateral bending you are describing for concrete beams is what is commonly know as secondary axis bending (Moment 2-2 in ETABS), as opposed to main or primary axis bending (Moment 3-3- in ETABS) which is along the vertical plane.

2. If the beams support slabs, then moment 2-2 will be negligible as the slabs prevent horizontal moment. If you have a cantilever beam without lateral restraint, or a beam like a gantry beam between portal frames, then this beam can be subjected to both moment 3-3 (due to vertical gravity/live loading) and moment 2-2 (due to wind or gantry surge loading horizontally).

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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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