Research On The Overall Stability Of Crane's Lattice Jib With Main And Vice-Jib Structure

With the demand of the engineering construction development, the development of crane is increasingly prone to large-sized, dominant-mountain and lattice. By the great deal use of the high-strength steel material, the structure strength is raised, but the problem of structural stiffness and structural stability is made to show to project. The stability analysis of complicated lattice structure becomes the crux of contemporary and large crane structure design and its calculation. The overall stability analysis of the crane's lattice jib with main and vice-jib structure is even more difficult to technician in our country. So it's very necessary to seek a simple, utility and effective method to solve the difficulty.By means of analyse to the cantilever lattice structure such as crane body, a simple algorithm is introduced. Though the contrast of the algorithm used in cantilever lattice structure and cantilever solid web beam, we can get the algorithm that can be used to calculate the equivalent inertia moment of the lattice structure when it is regarded as solid web beam. Based on the research to the stability variable cross-section beam, the bending defection differential equation of the variable cross-section beam in critical state of bucking is established. According to the edge condition of the structure, the differential equation is solved and bucking equation of variable cross-section beam is created. We can get the algorithm which can be used to calculate the equivalent inertia moment of the variable cross-section lattice structure when it is regarded as constant cross-section of solid web beam. The application of finite element method in the stability analysis is studied, by calculate the lattice structure's critical force with finite element method. The initial moment method is improved. So we can analyse the stability of lattice structure as solid web beam without change its geometry dimension.The out-of-plane stability of bending beam, which is made up with 2 beams and loaded by non-directional force, is studied. The bending and torsional deflection differential equation of each beam is established in critical condition. According to compatibility conditions of deformation, the characteristic equation is obtained to calculate out-of-plane stability of the cantilever bending beam.