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

With the constant development of society and technology, as well as, the unremitting pursuance of the construction enterprises for more benefits and higher efficiency, integrative suspension-and-installation projects become more and more prevalent, thus caused a more and more demanding request of lifting ability, working extent and height of the cranes used for suspecting and installing. Modern cranes tend to be larger, higher, more ingenious and lattice structural. The adoption of ample high-strength steels has improved the structure strength, but it has also made the problem of intensity and stability more conspicuous at the same time. The stability analysis of complex truss structure gets to be the nodus of the calculations in the structure designs of modern good-size cranes. Tracklayer-cranes' arms are good-size space-hyper-static truss structures made up by jointing steel tubes. The finited-element technique is often used to perform calculations in designs in projects. The analysis of integrative stability of the lattice structural arms of tracklayer-cranes with main & subsidiary arms is even the puzzle for designers and analyst in our country. So we conclude that it is very necessary to seek for pithy, practical and efficient techniques following crane designing criterions.By analyzing force bearing status of cranes' arms, adopting enlarge-coefficient techniques to work out section bend quadrature, then we can use stress technique to collate the integrative stability of it.A convenient formula to calculate the horizontal displacement of the cantilevered end was introduced. On this basis, by a method to compare the displacements, a formula was reached to calculate the equivalent inertia quadtature, when two-limbs lattice structural component and four-limbs lattice structural component are equal to abdomen-solid component. Without changing the length of components, the equivalence between the lattice structures and abdominal structures has come true. Through the method of calculating the equivalent inertia quadtature, we conducted a preliminary study about the stability calculation of variable cross-section lattice members, and reach to a characteristic equation which describes the stability-losing of the variable cross-section beam which was hinged at both ends.The stability-losing problems of bending beam which is component of two beams and under the force from horizontal and vertical directions have been studied, through the establishment of differential equations of each beam bending, reversing and deformation under the critical state, according to the boundary conditions of bar deformation and coordinating relations between the transformative bars, we achieved a characteristic equation that describes the stability-losing beyond the plane of the bending beam whose one end was fixed and the other was cantilever when it is under the force from horizontal and vertical directions, and had a discussion.Studied the integrative stability of the lattice structural arms of tracklayer-cranes with main & subsidiary arms, the methods to calculate stability critical load in and out of the lattice structural jibs with main & subsidiary arms lifting plane and using stress technique to collate the integrative stability are presented. Specific examples are given to show the method and steps to calculate the the integrative stability of the lattice structural arms of tracklayer-cranes with main & subsidiary arms.