Concise buckling analysis of stayed columns

Abstract The columns considered consist of a uniform central core with N identical stay frames equally spaced around it. Every stay frame usually involves short arms, which each have one end connected directly to the core and the other end connected by taut stays to the ends of the core and/or the ends of the two adjacent arms of the frame. This paper examines the critical buckling of such columns analytically and draws many general conclusions, the most crucial of which are confirmed by check calculations. The main conclusions include the following. Buckling can be divided into two types, which can be represented exactly by two simple substitute columns whose complexity is independent of N. Also, buckling is impossible if usual prestressing procedures are used and the column is stable under prestress alone and when fully loaded. Thus both substitute columns must apparently be used for each of these two load cases. However, these four substitute column calculations can often be reduced to one, or even to a single simpler substitute plane frame calculation. Finally, minimum weight design procedures should use N = 3, because the lightest design for N > 3 is always equalled or bettered by the optimum N = 3 design.