8-9. A 6-m long column is fixed at both ends. The cross-sectional area of this column is shown in the figure. If the modulus of elasticity follows . Determine the distribution of the critical axial buckling load. If the axial load acting on the column folllows , determine the probability of failure. Assume that E and P are independent.
Solution:
Section Properties
Then, the critical axial buckling load is
; .
Since , we have
Thus, the critical axial buckling load follows . Ans.
Set , then , where
Thus, the probability of failure is
Ans.