hCp I

where h is the distance from the N.A. to the outside fibres of the strut.

2.9. Struts with eccentric load

For eccentric loading at the ends of a strut Ayrton and Perry suggest that the Perry-Robertson formula can be modified by replacing Co by (Co + l.2e) where e is the eccentricity. Then and rj' replaces t] in the original Perry-Robertson equation.

(a) Pinned ends - the Smith-Southwell formula

For a more fundamental treatment consider the strut loaded as shown in Fig. 2.10 carrying a load P at an eccentricity e on one principal axis. In this case there is strictly no 'buckling" load as previously described since the strut will bend immediately load is applied, bending taking place about the other principal axis.

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