Buckling Load Factor
The buckling load factor (BLF) is the factor of safety against buckling or the ratio of the buckling loads to the applied loads. The following table illustrates the interpretation of possible BLF values:
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BLF Value (factor of safety)
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Buckling Status
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Notes
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1 < BLF
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Buckling not predicted
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The applied loads are less than the estimated critical loads. Buckling is not expected.
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0 < BLF < 1
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Buckling predicted
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The applied loads exceed the estimated critical loads. Buckling is expected.
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BLF = 1
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Buckling predicted
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The applied loads are exactly equal to the estimated critical loads. Buckling is expected.
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BLF = -1
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Buckling not predicted
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The buckling occurs when the directions of the applied loads are all reversed. For example, if a bar is under tensile load, the BLF should be negative. The bar will never buckle.
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-1 < BLF < 0
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Buckling not predicted
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Buckling is predicted if you reverse all loads.
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BLF < -1
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Buckling not predicted
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Buckling is not expected even if you reverse all loads.
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Generally, a structure can have both positive and negative buckling load factors. For example, imagine a cylindrical vessel under internal pressure supported by columns. The vessel will never buckle as it is under tension, however the columns may buckle as they are under compression.
Calculating Buckling Loads
To calculate the buckling load(s) for a mode, multiply all applied loads by the BLF for that mode. For example, suppose that you applied the following loads:
and the buckling load factor (factor of safety) for mode 1 is calculated to be 2.3, then buckling in mode 1 will occur if you apply:
Related Topics
Linearized Buckling Analysis
Performing Buckling Analysis
Thermal Effects for Buckling Studies