A steel post is formed by welding two steel plates to a W360 x 64 wide flange section. The plates are 15 mm thick, and their widths match the depth of the wide-flange section. If the post is 6 m long and modeled as simply supported, determine
(a) the buckling load if A-A is the neutral plane of bending and
(b) the buckling load if B-B is the neutral plane of bending. (See Appendix E.)