The Elastic Stability Analysis Of Indeterminate Truss Structure In Construction Crane

Steel truss with light weight, large capacity of pressure and bending moment, is widely used in heavy mechanical structure and high-rise building structures, such as tower cranes tower, crane, construction elevator guide rail racks.Because these structures directly determines the reliability of the equipment safety, the relevant specifications of its strength, stiffness and stability is highly demanding. High-rise structure and its component bars are slender structure, stability calculation in the design is utmost important. With the rapid development of materials science, high-strength structural steel have been widely used in steel structure which bearing capacity as large as possible, quality of light as far as possible, at this point, relative to the structural strength and rigidity checking, Crane metal structure increasingly highlighted the importance of stability analysis which is also the main contents of this article.Currently large-scale finite element method is to the most effective way calculate truss structure. However, the finite element analysis of statically indeterminate truss structures in engineering software often encountered that the overall is stable but local unstable, analysis of finite element software mistakenly believe that the critical local buckling strength is the critical load of structural instability, and sometimes the overall structure of the critical buckling force is much larger than the real critical force of local buckling. Designers in the project is more concerned about the stability of the structure to withstand the actual critical load, that is when the structure overall buckling occurs. It is the basis to determine the structural stability of the safety margin, optimize the structure design. Thus the how to determine the critical buckling load of the overall structure is the most important issue of stability design.This article discusses two different forms of instability in the truss structure:truss buckling and single-limb buckling. In this paper, the reason of the instabilities and the connection between these instabilities and overall buckling of the structure are researched. The connection of the two kinds of buckling transformed into each other when the structure parameters are changed is proposed.According to stability analysis of finite element theory, the discriminant of truss structure critical instability is derived by using accurate finite element theory to analyze the stability problem of truss element stiffness matrix. Combined with the discriminant the two different types of structure buckling is described, and the reason of the mistaken in finite element analysis of statically indeterminate truss structure stability is explained. According to the stability theory of rods, the method to resolve the mistaken in finite element software is proposed. Based on the above method, stability analysis program is compiled to analyze the stability in general truss structure, the real critical buckling load of truss structure is obtained, which could be used in structural design and check by engineers.Using the above stability analysis program, tower structure stability of STL80 tower crane is analyzed. The influence on the tower stability of tower height, wind load, overturn moment is discussed, and the stability of the tower in working conditions is checked.