Civil Engineering/slab panels


panel query
panel query  
I have the following queries about how to consider a panel in a solid slab.
1.i believe that if it is a two way solid slab, obviously supported by for beams on the four edges , then it must be considered a panel. is it compulsory for it to be considered as a panel for the beams to be supported by columns on the four corners ? the attached picture, if you look at the picture at top it is a simple example of a panel., but the bottom picture as you can see has a beam in the middle and obviously the beam is not supported by columns at the ends. now how to consider a panel in the bottom..?

please explain the above queries sir.

ANSWER: Hi Arsalan,

1. For top image, if the L:B ratio is much more than 2, you can design the slab as 1-way spanning in the shorter span direction.

2. For bottom image, the slab can be considered as 2 panels, with continuity across the middle beam and discontinuity along the outer beams. With such proportions (almost 1:1), both panels can be designed as 2-way spanning

These comments apply to a solid homogeneous slabs. If you have ribbed slabs or Hollow core slabs, then they are always 1-way spanning.

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thanks for your answer, do you mean while considering a panel for two way slab , we need to just ensure that slab is supported by four beams and not required to support those four beams by four columns or may be three columns. is it not necessary for the slab to supported by beams and then the beams to supported by columns on four column support to beams not a criteria while forming a panel? please explain.

Hi Arsalan,

1. Yes, but you could still design it as 1-way spanning if you use a ribbed slab or HC slab.

2. Yes, they can- the middle beam does not need to be supported on columns; so long as the main beams are stiff/strong enough to support the middle beam without too much deflection you can design the 2 panels as 2-way spanning.

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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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