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Civil Engineering/Etabs 13 Load Pattern


QUESTION: Dear sir,

First I would like to thank you for your efforts.

My question is :
In Etabs 13 they gave you the ability to define earthquake (static) into one single load pattern. If you go to see forces resulting from a combination including that pattern (BMD for example) you will find three options : Max, min & absolute max.

I wonder which one the design is carried out with?
Also, the absolute max gave me the max negative value but it didn't do so with the max positive one.

Note : I did my test on a column with EQ Static and defined Comb1=1.0EQ to compare the results of each step in the case with the combination.

Thanks in advance.

Best regards.
Wael AlOqaily

ANSWER: Hi Wael,

If you display the design results on the frame, then right click on the member you wish to check on, the tables will display which governing load case or combo the design is based on.

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

QUESTION: Thanks for answering my question. But it seems that I need to make some explanation to get you to the point.

Suppose that the controlling combination Ucon3=1.2D+1.0EQ
Since EQ involves 6 steps (X,Y,X+e,Y+e,X-e & Y-e),
how can I know which step is used in calculation of combination Ucon3 ?

Hi Wael,

OK, I understand now. What you will need to do is look at the governing design forces when you right click on the member displaying the rebar and make a note of these. Then you go to Display>Tables>Column/Beam Design forces and scroll down to where the EQXY forces are listed.  These will have 1 to 6 as suffixes against the EQXY load case, so you can then compare the values.

I believe that is the only way to check. Of course you could define the X and Y cases separately, to make such interrogation easier.

Civil Engineering

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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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