Progressive Collapse Analysis Of Double-layer Spherical Reticulated Shell In Construction Process

Double-layer reticulated shell is one of the main forms of spatial structures especially large-span structures, widely used in large public buildings and industrial buildings. Currently, the research and analysis about progressive collapse of structures is just in use process after the completion of construction instead of construction process domestic and international.On the basis of a detailed summary of researching progress about progressive collapse of framework structure, truss structures and grid structure domestic and foreign as well as progressive collapse specifications of various countries across the world, this paper makes research on a cement factory cement prehomogenization storehouse double spherical reticulated shell in Tianjin which is in construction process, we use ABAQUS finite element analysis software as a numerical simulation platform to establish the said reticulated shell progressive collapse numerical analysis model after completion of the design using engineering software MSGS in accordance with the relevant specifications, and then take a static analysis and a dynamic analysis for this structure.Static analysis is a method that uses a static load to simulate the dynamic effect by the failure of some element. In static analysis,we firstly determine the key elements after classifying the elements according to the different orientations and functions, then use "component removal method" to analysis the response of remaining structure considering the power amplification after the initial damage of a certain key element. Then it judges whether the progressive collapse destruction will occur on the structure through the continued removal of the new damaged elements.Dynamic analysis is a method that applies dynamic load to the structure directly to simulate the dynamic effect by the failure of some element. In dynamic analysis, we use “equivalent load unload law considering the initial state” to study the dynamic response after the initial destruction. The method can simulate element subsequent sudden failure under the condition of the initial state of the overall structure before failure in one calculation process. It determines the equivalent load through discussion of the initial time and expiration time. It obtains the progressive collapse mechanism of the structure according to one element failure in the construction process of the double reticulated shell and makes a comparison and a summary of the collapse mode due to initial failure of elements of different location. Then it makes a comparison between the calculation result of static method and dynamic method, and gives the proposal values of dynamic magnification factor DIF in static method by comparing the stress of typical elements and the displacement of typical nodes of the two methods. Then a analysis result show that the critical wind load can be improved significantly by increasing the cross section of the key element or add an temporary support at the hole, then four methods to reduce the probability of structure progressive collapse in the construction process, such as reducing the probability of accident events, strengthen the conceptual design, increasing the section of key elements and setting two temporary supports at the hole.