Analysis On Unloading Of Large Span Steel Structures And Research On Its Mechanical Analysis

Steel structure is an ancient and vibrant material. Recently our steel industry has undergone enormous changes. Further more our country host various kinds of international and domestic sport games or exhibitions, more and more stadium structures and exhibition structures have been built. The large span steel structure can satisfy the requirement for the large public event, not only for the architectural aesthetics, but also to fulfill the mechanical requirements. At this present stage, it has encountered some diversity and complicate problem in the large span steel structures construction methods which result in the construction phase's internal force distribution much more complex. The force in the main structure is changing with the construction process. The most important phase in such phase is removing the temporary supported structures at the end of the main structure's completion. To remove the temporary support will lead to the internal forces in the main structure redistribution, which maybe influence the security of the structure. It's necessary to simulate the whole process of the unloading to recognize the changing rule of the internal force of the structure with various construction methods respectively.This research is based on the background of a stadium local city. The general finite element software ANSYS is used to simulate the unloading process. The main research contents list as follow:(1) Using a link rod connected of the multi-span beam system to equivalent to the large span steel structure and using different way to unloading this equivalent system. The calculation result can guide the actual construction process. Established access system can realize the unloading process reliability.(2) Analysis the internal force of the grid structure by the elastic method in the construction stage. Getting the internal force changing rule of the grid structure. Providing merits and faults and the redistribution and deformation influence of the main structure with the four types of unloading methods respectively.(3) Using finite element methods, to establish the actual stadium model. Simulating different unloading process. Using the geometric nonlinear analysis theory of the temporary support system, getting the eigenvalue buckling and extreme point buckling (with defects) critical bearing capability of the support systems. Study the different materials influence. Find the changes of the supporting structure of the tire rack ability under the environmental changing.