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Warning in Non-linearly Static Analysis in Etabs 2016

Warning in Non-linearly Static Analysis in Etabs 2016

Warning in Non-linearly Static Analysis in Etabs 2016

(OP)
Dear Alls,
I have faced this warning in Etabs2016, How can I solve it?

For Slab Combination and Wall Combination

"
----------------------------------------
BASIC STABILITY CHECK FOR FORCE-CONTROLLED NONLINEAR STATIC LOAD CASES:
NUMBER OF NEGATIVE STIFFNESS EIGENVALUES SHOULD BE ZERO FOR STABILITY.
(NOTE: FURTHER CHECKS SHOULD BE CONSIDERED AS DEEMED NECESSARY)

NUMBER FOUND AT FINAL CONVERGED STATE = 2

* * * W A R N I N G * * *
THE STRUCTURE IS UNSTABLE OR ILL-CONDITIONED !!
CHECK THE STRUCTURE CAREFULLY FOR:
- INADEQUATE SUPPORT CONDITIONS, OR
- ONE OR MORE INTERNAL MECHANISMS, OR
- ZERO OR NEGATIVE STIFFNESS PROPERTIES, OR
- EXTREMELY LARGE STIFFNESS PROPERTIES, OR
- BUCKLING DUE TO P-DELTA OR GEOMETRIC NONLINEARITY, OR
- A FREQUENCY SHIFT (IF ANY) ONTO A NATURAL FREQUENCY

TO OBTAIN FURTHER INFORMATION, RUN AN EIGEN ANALYSIS FROM
THE END OF THIS NONLINEAR CASE USING AUTO FREQUENCY SHIFTING
(WITH ADDITIONAL MASS IF NEEDED) AND INVESTIGATE THE MODE SHAPES "

For Concrete Frame Combination
"* * * W A R N I N G * * *
MAXIMUM NUMBER OF NULL STEPS REACHED FOR
CASE: DCON28-NL
SUBSEQUENT RESULTS WILL NOT BE AVAILABLE"

Many Thank for Replying

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