Nonlinear Calculating Method for Multi-Bar Luffing System of Giant Crane Considering the Sagging Effect

Abstract

The luffing system of giant jib crane is usually consisted of rigid bars and flexible cables, and the weight of components causes sagging deformation and large displacement. In order to study the nonlinear method for multi-bar luffing system of giant jib crane, this paper completed theoretical analysis and example verification. Based on catenary theory, the equation of luffing strand was obtained. Spatial multi-bar equation of three bars was proposed and it was extended to any more bars. Then, equilibrium equations of components were written in sequence, and the equations of multi-bar luffing system were established with the elastic deformation of multi-bar and luffing strand. Finally, by taking the 2500-ton ring crane as an example, the results demonstrated that: the nonlinearity of combined multi-bar luffing system negatively influences the structural behavior, and the results calculated by the proved nonlinear method is more reasonable and closer to the actuality than the linear method, so it provides theoretical basis for engineering design and construction.