Collapse Resistance Analysis Of Double-Layer Grid Shell Structure Based On Key Rods Reinforcement

In recent years,large-span space steel structures play an important role in the fields of human production and life,and large-scale double-layer reticulated shell structures are also widely used in practical engineering.Due to the accidental nature of the structure during its actual service,the consequences are likely to exceed the original estimates of the designers.Some cases of continuous collapse of the whole reticulated shell caused by local failure of some key members also exist.Because the long-span double-layer reticulated shell is a multi-statically indeterminate structure connected by many rods,there is no clear standard to identify the key rods in the structure.Therefore,it is of great engineering significance to find a suitable method to determine the key members of the double-layer reticulated shell structure,and take effective measures to strengthen it.Through the anti-collapse analysis and simulation of the structure,it is judged that the effect of strengthening based on the key members to improve the anti-collapse performance of the double-layer reticulated shell structure.Based on the research background of an actual double-layer reticulated shell structure,this paper mainly uses SAP2000 finite element software for theoretical analysis and numerical simulation.The specific research work and conclusions are as follows:(1)According to the eigenvalue buckling analysis,the large deformation response area of the double-layer reticulated shell structure is initially determined,and the large displacement node is selected as the monitoring node of the nonlinear static whole process analysis under displacement control.The nonlinear whole process analysis of the structure is carried out considering the different distribution of live load.The skeleton curve of plastic hinge is combined to identify the position of the failure member in the structure from the initial loading stage to the failure process.The importance coefficient of the member is introduced to judge the importance of the failure member in different positions,and the importance coefficient of the failure member near the support is determined to be relatively high.It is the key member in the double-layer reticulated shell structure.(2)Based on the instantaneous load method,the dynamic nonlinear time history analysis of the double-layer grid shell structure under different live load distribution is carried out to equip the joint,and the dynamic effect of the remaining structure is generated by removing the failed members,and the deformation criterion and strength criterion of the double-layer grid shell structure are combined to simulate the collapse of the structure under dynamic action,and the corresponding analysis flow chart is proposed to illustrate the analysis steps and ideas.By analyzing the response of the remaining structure,it can be seen that when a certain number of failed members near the support is removed,the collapse failure of the entire structure of the structure will occur,indicating that the members near the support are of high importance,and the correctness of the key member identification method studied in this paper is also verified.(3)Different reinforcement methods were selected to reinforce the key members in the structure,the reinforcement method suitable for the key members of the double-layer grid shell structure was determined,the ultimate bearing capacity of collapse resistance under static load before and after structural reinforcement was compared and analyzed,and the reinforcement method suitable for the key members of the double-layer grid shell structure was determined,and the bearing capacity of the overall structure could be improved only by enhancing the material strength of the key members or increasing the cross-sectional area of the key members,but the degree of improvement was limited.At the same time,the material strength and cross-sectional area of the key members of the double-layer grid shell structure can be appropriately improved,which can effectively improve the collapse bearing performance of the overall structure under static load.(4)According to the seismic code,two natural seismic waves and one artificial seismic wave were selected to analyze the dynamic time history of the double-layer reticulated shell structure.The principle of strain energy and the target of seismic standard displacement are introduced to analyze the collapse resistance of structures under rare earthquakes.The dynamic response of the reticulated shell before and after the reinforcement of the key member is compared and analyzed,and it is further verified that the effective reinforcement measures for the key member of the double-layer reticulated shell structure can effectively improve the anti-collapse ability under earthquake.