Civil Engineering/etabs warning

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QUESTION: Dear Sir,
In my analysis of a 3B+9+roof building ,I have got warning like as follows, How I can clear this commands

NUMBER OF STIFFNESS DEGREES OF FREEDOM    =      119603
NUMBER OF MASS DEGREES OF FREEDOM         =       59208
NUMBER OF RITZ MODES SOUGHT          =          25
NUMBER OF STARTING VECTORS          =          3
VECTOR BLOCK SIZE          =          3
FREQUENCY SHIFT (CENTER) (CYC/TIME)       =     .000000

* * * W A R N I N G * * *
THE STURM-SEQUENCE CHECK FOUND     286 EIGENVALUE(S) BELOW THE SHIFT,
RITZ ANALYSIS REQUIRES ALL EIGENVALUES TO BE ABOVE THE SHIFT


* * * W A R N I N G * * *
NO EIGEN OR RITZ MODES WERE FOUND,
NO RESPONSE-SPECTRUM OR TIME-HISTORY ANALYSES CAN BE PERFORMED

Thanks & Regards,

ANSWER: Hi Ravi,

You must have some discontinuity or other problems. Do a static self weight deformation check, increase the scale and then animate to see if some members are deflecting excessively.

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

QUESTION: Hi Sir
Good Day
How I can do a static self weight deformation check? appreciate for your guidance..
Regards,

Answer
Hi Ravi,

Basically do just a static analysis without dynamic parameters and check the deformed shapes. You can also try to do a Standard Solver instead of Advanced Solver under Analyse>Advanced SAPfire Options, as this will output more details of problems with your model (check Last Analysis Run Log).

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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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