Gordon's formula

A column formula. Also called Rankine's formula:

<tex> P = \frac{s}{1+a\frac{l^2}{r^2}} </tex>

where:

<tex>P</tex> = the allowable unit stress for the column

<tex>s</tex> = the allowable unit stress for blocks

<tex>a</tex> = a constant depending on end conditions, etc.

<tex>l</tex> = the unsupported length of the column

<tex>r</tex> = the least radius of gyration in reference to an axis normal to the plane in which flexure takes place