Instability Check

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Instability Check





We want to assess the ultimate limit state of instability for the above isolated cantilever column only for X direction as in the example reported in /7/.

In the above Section Data window are assigned (no data for Y direction):

- Concrete class: C40/50

- Steel:  B450C        

- Dimensions (Side X, Side Y) of the rectangular section of the column: 70x70

- The longitudinal bars 10+10Φ24 are assigned as 1 bar Φ24 /corner and n. 8 web bar Φ24 along Y direction.

- Design constant axial force:  1000 kN

- First order moment MX0d =        Nd e0 + Fd l =  1000 0.40 + 40 12.00 = 880.00 kNm

- Eccentricity eX for geometric imperfections: 0.00 cm (already included in e0)

- Effective length l0X = 1200 2 = 2400 cm according to fig. 5.7 g) in §


If we check the option "with uniaxial eq. (5.34)" the output is:



The second order moment 385 kN is very near to 390 kN obtained in /7/.


If we check the option "with biaxial moment-curvature diagram" the output is:




Last results are less conservative but near to the previous. The "model column" diagram is: