Space Grid Structure's Criterion Of Failure Modes And Design Improvement

The failure modes of grid structure under the static and dynamic load are analyzed, these are shown that grid structures can not form an effective load path after the local components damage, so the failure modes always have obvious characteristics of progressive collapse and the grid structures anti-progressive collapse capability is weak. According to analysis, The continuous collapse criterion is suggested in static and dynamic, the optimization design method is proposed under static load and the analysis method based on secondary defense capabilities is put forward.First of all, it reviews progressive collapse research and introduces grid structure collapse accidents at home and abroad. After analyzing the grid structures energy-consuming mechanism and failure mode under the static limit loads, grid structure collapse criterion is proposed under the static load. The criterion includes deformation, total deformation energy and the failure mode, it can effectively analyze and determine the grid structure collapse and destruction ductile failure mode, and evaluate the performance of the ductility.Grid structures failure mechanism have been investigated in Chapter III and IV, and continuous collapse criterion is established under dynamic loads. The criterion reflects the connection of overall deformation, total deformation energy and the failure mode, accurately analyze and determine the structure failure mode of destruction, and evaluate the performance of the ductility. The grid structures collapse forms under earthquake can be divided into ductile failure and progressive collapse mode. The ductile failure has characteristics such as in-depth plastic development, full bearing capacity and large displacement; the progressive collapse of the grid structures, the development of plastic deformation is opposite. In different earthquake wave peaks, the grid structures failure mode will change between the ductile failure and progressive collapse. Cumulative damage effect to failure mode is analyzed under earthquake In chapter V. By comparing failure modes considering cumulative effects or not, it is shown that the cumulative damage effect has impact on the failure mode. In the Chapter VI, by introducing column based on the central plastic hinge model, it is verified that bar instability will have a significant effect on capacity and damage model of grid structure. Based on grid structures failure mode, A optimization model is put forward by lengthened calculation length of the pressure bars in Chapter VI. Based on the alternate load path method, it proposes analysis method of secondary defense capability which can be applied in the grid structure. It can effectively simplify analysis the grid structure resistance capacity of progressive collapse.