As per IS 456: 2000, the unsupported length (l) of column whose one end is unrestrained in any given plane shall NOT exceed (Given: b = width of the column cross-section and D = depth of cross-section measured in the plane under consideration)
(Symbols and notations carry their usual meaning)
1
(100 b) / D
2
(100 b3) / D
3
(100 D2) / b
4
(100 b2) / D