Difficulty: Easy
Correct Answer: Less than
Explanation:
Introduction / Context:Euler's buckling theory relates the critical (crippling) load to the boundary conditions via the effective length. Knowing how end restraint changes buckling capacity is essential for safe column design.
Given Data / Assumptions:
Concept / Approach:Euler load P_cr = (pi^2 * E * I) / (l_e^2), where l_e is the effective length. For pinned–pinned: l_e = l. For fixed–free: l_e = 2l. Larger l_e reduces P_cr quadratically.
Step-by-Step Solution:
Pinned–pinned: P_cr,pp = (pi^2 * E * I) / (l^2).Fixed–free: P_cr,ff = (pi^2 * E * I) / (2l)^2 = (pi^2 * E * I) / (4l^2).Ratio: P_cr,ff / P_cr,pp = 1/4 → fixed–free carries one-quarter of the pinned–pinned capacity.Therefore, P_cr for fixed–free is less than that for pinned–pinned.Verification / Alternative check:Effective length factors K: K = 1.0 (pinned–pinned), K = 2.0 (fixed–free). Since P_cr ∝ 1/K^2, doubling K quarters the load, consistent with the result.
Why Other Options Are Wrong:
Common Pitfalls:Confusing fixed–free with fixed–fixed (the latter has higher capacity, K = 0.5).
Final Answer:Less than
Discussion & Comments