Study On Control Of Installation Stress For Large Span Grid Structure In Slicing Construction

Grid structure is widely used for roof structures of gymnasiums, hangars, exhibition halls, waiting halls and workshops and so on because of its good mechanical properties, higher integral rigidity, seismic performance, light weight, making installation easyly and low cost.The installation of large span truss structure commonly use Construction of high-altitude slice bulk method, which is the construction process of part of the structure gradually installed as the overall, so it has different structure forms,boundary conditions and load form in various stages of construction, and that is, the force and deformation of structure change with the construction process. The force and displacement of the structure may exceed the use phase, so that the structure may be at risk during the construction period. The general structural analysis sense that the the entire structure is shaped at one time, this analysis method does not take into account the structure of the forming process. When considering the construction process, the stress state of the structure after forming is not only associated with different construction methods, but also the different construction order in the same construction method.In this paper, the development status of grid structure and the main construction methods are briefly introduced. With the background of the specific project, finite element analysis software ANSYS was adopted to simulate the construction process of the grid according to the traditional construction methods. Stress and displacement of the structure in each construction step are obtained, and compared and analyzed with analysis under complete loading:the maximum internal force of grid structure appears in a certain step in the construction process, rather than in the step of completed construction; the final stress and displacement of structure calculated by fractional step loading method are greater than that calculated by complete loading method.The traditional construction method easyly make the structure have a greater installation stress in the construction process, there is no good solution to this problem. therefor this paper proposes two new construction methods, back lift-up method and late installed band method, and simulate the construction process by ANSYS. The calculated results are compared and analyzed with the calculated results of the traditional construction methods:back lift-up method and late installed band method can effectively reduce the installation stress in the construction process, this paper provides a new and more reasonable construction methods wih the large span grid structure construction.