Structural instability

What this module covers

• Distinguish a strength failure from an instability failure
• Use the Euler formula for a slender column
• Apply effective length to different end conditions
• Explain why buckling happens about the weak axis
• State the limits of Euler theory and why real columns differ

Lessons

1. 18.1

   Deriving the Euler buckling load

   Why a strut fails suddenly at a particular load — an eigenvalue problem, solved from scratch.

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2. 18.2

   Strength versus stability

   Two completely different ways for a column to fail.

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3. 18.3

   Effective length, slenderness and the limits

   How end restraint helps, which axis buckles, and where the theory runs out.

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4. 18.4

   Real columns, and buckling by energy

   Why no column reaches its Euler load, and how to estimate one that has no formula.

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5. 18.5

   Beam-columns: bending and buckling together

   What happens when a member carries transverse load and axial compression at once.

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