Out-of-plane Stability Analysis of Combined Boom System with Main Jib and Fly Jib

摘要

The objective of this study is to develop an analytical method for the out-of-plane stability of combined boom system with main jib and fly jib. Boundary conditions and deformation compatibility equations are introduced to get the analytical expression of out-of-plane buckling characteristic equation by establishing the bending and torsional deformation differential equations of jibs and the strut under the instability critical state. The analytical results obtained agree well with the finite element method (FEM) results. The influence of the dip angle between the main jib and the fly jib on the stability of the boom system is discussed. And the comparison between the combined boom system and the bending beam-column in the stable bearing capacity is made. It is shown that the upwards-bend boom system is much stronger than the downwards-bend boom system. There exists a certain dip angel between the main jib and the fly jib that makes the stable bearing capacity biggest. By comparing the stable bearing capacity of boom system with that of the bending beam-column, it is obtained that the flexible tension system will significantly improve the stable bearing capacity of the bending beam-column.