Machine-translated by Google. Questions are authored in English.
Top

Discussion

For the beam-column configurations shown in figure, the minimum Euler buckling load is obtained for the case (Young's modulus and second moment of cross-sectional area are as indicated)

  • A.Column pinned at both ends, EI, length L, with a spring K at mid-span, loaded by an axial end force P
  • B.Column fixed at one end and free at the other, E and 2.0 I, effective length 0.7 L, loaded by an axial end force P
  • C.Column fixed at one end and free at the other, EI, effective length 0.51 L, loaded by an axial end force P
  • D.Column pinned at both ends, EI, length L, loaded by an axial end force P

Answer: C

The minimum buckling load is in case (iii).

Euler's load is \(P = \pi^{2}EI/(KL)^{2}\) with effective length factor K = 2 for a fixed-free column and 1 for pinned-pinned. In units of \(\pi^{2}EI/L^{2}\):

\[ \begin{aligned} \text{(ii)}: &\ \frac{2}{(2 \times 0.7)^{2}} = \frac{2}{1.96} = 1.02 \\ \text{(iii)}: &\ \frac{1}{(2 \times 0.51)^{2}} = \frac{1}{1.0404} = 0.96 \\ \text{(iv)}: &\ \frac{1}{1^{2}} = 1.00 \end{aligned} \]

Case (i) is case (iv) with an extra spring support part way along, which can only raise the buckling load above 1.00. So (iii), at 0.96, is the lowest.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.