use of pile overload equations api rp2a

huangyhg

use of "pile overload" equations api rp2a
when can i use "pile overload analysis" to check a pile?
in the working stress design edition of api rp2a, there is an equation for "pile overload analysis" for cylindrical members. equation 3.3.1-6. this equation evaluates the sections with the plastic section modulus "z", and under a sometimes pretty high allowable stress "fcx". there is no limitation to what class steel sections this formula applies to. it seems to me that slender and non-compact sections that fall under the "local buckling" limitations for bending (both elastic or inelastic) should not be checked by assuming a plastic distribution of stresses, nor by comparing such bending stress to the local buckling stress for axial loads (fcx). also, this equation does not take into account overall stability of members for axial forces (buckling)... the code has no commentary on this equation? can anyone shed some light on this issue?