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Civil Engineering/ETABS analysis log warning

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Question
Cnstr error
Cnstr error  
QUESTION: Hi M. Khan,

I am modeling a 8 stories RCC building with a steel roof in ETABS.

As the building got a couple of steel joists at the roof, I draw a deck (floor) to replace these joists in the model.

Now please see attached the error that I get when I run the analysis.

I looked at the location on the model and there's pretty much nothing there (close to a beam but that's it). It's not a joint location either.

Do you know where the error comes from and how to solve it?

Thank you,

Best regards,

ANSWER: Hi Frederik,

It's difficult to say without looking at the model, but 6.9 digits loss of accuracy is not very significant. However, you could try and resolve it by exporting the model to text (.e2k) and then importing back into ETABS- that may sort it out. Then do a  final check on base reactions against input loading.



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

Cnstr error
Cnstr error  
QUESTION: Thanks for the answer,

Now I am stuck with over many digits loss...which I guess is now significant.

I tried to export and then import but nothing really new.

Would you have a couple of other actions to try?

Thanks,

Answer
Hi Frederik,

Yes, please follow the advice in the error messages- seems like you have some connection problems or mechanism. If the model runs for just static analysis, look at the deformed shape for dead load, scale it up and animate it- you may see which member/element is deforming too much, so that you can fix that.

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Arshad Khan

Expertise

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.

Experience

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.

Organizations
.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)

Publications
•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

Education/Credentials
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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