If individual parts or plate elements buckle, without overall buckling of the member, this is known as local buckling or local instability.
- Width/thickness ratio of each part gives the slenderness ratio of the element. This ratio controls local instability.
- It should never be allowed before overall buckling of the structure except in few cases like web of a plate girder.
Flange local buckling
If width over thickness ratio of the compression flange is greater than a certain limit, flange can buckle locally. This is known as flange local buckling.
Web local buckling
If depth over thickness ratio of the web is greater than a certain limit, it can locally buckle or cripple under compression.
- Web local buckling occurs in a diagonal position and is produced by the diagonal compression existing in the web due to shear.
- Web crippling occurs due to local compression transferred by the flange to the connecting portions of web.