Buckling of Heavy Bars

The calculation for the buckling of a short bar under compression occurs normally through the neglect of its own weight. This method is no longer permissible for long heavy bars. In this case, the net weight must be taken into consideration. Such long heavy bars can be found, for example, as drilling-risers in ocean exploration technology, as schafts in mining, as steel turrets for the production of energy and as naturally grown mammoth trees.

In this paper, the critical buckling forces are derived from ten end conditions for heavy bars which are surrounded by air and burdened by compression. There is an analytical solution to the differential equation of the problem which requires a numerical evaluation. Limited computer capacity permits calculations of critical buckling forces only up to a certain length. An analytical solution to the differential equation must be developed asymptotically for long heavy bars. With the help of this asymptotic evaluation, the critical buckling forces for long heavy bars are found.