Collapse Resistance Analysis of a Double-Layer Reticulated Shell Structure Reinforced with Critical Rods

Long-span spatial steel structures play an important role in the related fields of human productive activities and life, and large-scale double-layer reticulated shell structures have been widely used in actual projects. Due to the accidental events suffered during the actual service period of the structure is full of contingency, there are many cases of continuous collapse of the whole reticulated shell caused by the local failure of some key members. For example, affected by certain factors, the bending of critical members or the fracture of high-strength bolts at the joints make the reticulated shell structure unable to form an effective load transfer path after the failure of the critical members, and then the extension damage occurs, and finally the continuous collapse occurs, so it is necessary to study the effect of the reinforcement of the critical members on the collapse resistance of the double-layer reticulated shell structure in-depth. In this context, an actual double-layer reticulated shell structure was taken as the research object, and the SAP 2000 finite element software was used for modeling and analysis. Under the premise of considering the double nonlinearity of the structure and the initial defects, the whole process of nonlinear analysis was carried out for the reticulated shell under the action of displacement control, and combined with the development of plastic hinges, the location of failed rods was identified, and the critical rods were determined according to the importance coefficients of the failed rods. Critical rods were determined according to the importance coefficients of the failed rods. Three different reinforcement methods were selected to reinforce the critical members of the structure, and the ultimate capacity of the structure to resist collapse under static loads was analyzed before and after reinforcement. The dynamic time-history analysis of the double-layer reticulated shell structure was carried out under seismic actions, and the strain energy principle was introduced to analyze the collapse resistance of the structure under rarely occurred earthquakes, and compared and analyzed the dynamic response of the critical members before and after reinforcement.The results showed that: the strengthening of critical members could effectively improve the collapse resistance of the double-layer reticulated shell structure; the dynamic nonlinear time-history analysis of the double-layer reticulated shell structure was carried out by using the transient load method, and the correctness of the identification method of the critical members was verified by removing the failed members and analyzing the responses of the remaining structure; the comparison revealsed that the overall structural-bearing capacity could be improved by enhancing the strength of the critical members or increasing their cross-sectional area only, but the degree of improvement was limited. It was found that only by enhancing the material strength of the critical members or increasing their cross-sectional area could improve the bearing capacity of the whole structure, but the degree of improvement was limited, and by adopting the reinforcement method of enhancing the material strength and cross-sectional area of the critical members at the same time, the collapse resistance of the whole structure under static loads could be effectively improved; the collapse analysis of the structure under rarely occurred earthquakes was carried out, and the change of the strain energy of the double-layer reticulated structure with the reinforcement of critical members was smaller than that of the original structure before the reinforcement. It was further verified that effective reinforcement measures for the critical members of the double-layer reticulated shell structure could effectively improve the collapse resistance under earthquakes.