appears to be the case with increasing classes of struc- tures .... eccentricity, e, and that of the orthotropic section cens .... -s,f s (d. + i)'t. J = ( i) -- c, 3 ; d/t, < 1 (9a) with the 'end effects' correction factor, c, now given by .... 3s., .38 E. 636 & 63 4.26.