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Civil Engineering/Temperature difference loading for concrete


QUESTION: Dear sir,
Can you please explain what is the meaning of T in ACI load combinations? It is used for combined effects of creep shrinkage temperature etc..but I would like to know what is the meaning of Temperature? I mean do we take seasonal temperature difference as in winter and summer and then apply for example in ETABS or do we take the differenece between day and night temperature in a particular season?

ANSWER: Hi Waseem,

This depends on the sensitivity of the structure to expansion/contraction. If it is a long span structure or long length without joints you may need to first check effects of maximum (summer) and minimum (winter) temperatures.

But more routinely we check the daily variations as these occur regularly and the differential is usually in the range 15-20 degrees difference overall(in all seasons). If it is concrete you need to remember that there is a thermal lag period as concrete retains heat during the night and slowly takes up heat during the day.

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QUESTION: how but the case of temperature on etab model
whate the case of loading we take

Hi Waseem,

The load combos in which you include temperature are detailed in ACI-318 and ASCE-7. You need to decide how much temperature range to consider and which parts of the building to apply to- for example the roof slab/beams, or exposed external columns (not internal ones, as they are not subjected to much temperature range).

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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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