Stability And Collapse Resistance Analysis Of Large Span Single-layer Three-Way Spherical Reticulated Shells

In large-span space structures,single-layer spherical latticed shells are widely used.However,most of the previous studies on single-layer spherical reticulated shells are focused on small and medium span,while the studies on large-span single-layer three-way spherical reticulated shells are less.In view of this,a series of finite element simulation analysis is carried out on the large-span single-layer three-way spherical reticulated shell structure（hereinafter referred to as the structure）of the attached building of Hengqin Zhuhai navigation hotel in Zhuhai City,Guangdong Province,considering only geometric nonlinearity and considering both geometric and material nonlinearity.The influence of the main parameters,such as the form and size of the member section,the load distribution,the initial imperfection and the support condition,on the structural stability is investigated.The order of the buckling mode determining the structural stability bearing capacity is analyzed.The reasonable value of the initial imperfection of the structure in this order of buckling mode is discussed,and then the calculation formula of the structural stability bearing capacity in the elastic-plastic state is put forward,It is used to estimate the stability bearing capacity of the roof structure.In addition,by discussing the distribution of "sensitive members" of the structure under the action of uniformly distributed load in the whole span,the causes of structural failure and collapse mechanism are explained,and the overall collapse failure criterion of the structure is proposed.Then,by strengthening the local members,the component distribution which plays an important role in maintaining or enhancing the stability of the structure is determined,and the method is applied to the above engineering examples,The concrete measures to enhance the collapse resistance of the roof structure are put forward.The main conclusions and achievements are summarized as follows:1.Considering that the initial imperfection value L/200 and the live load distributed in half span have great influence on the structural stability,it is suggested that the initial imperfection value and load case should be taken as the basic case of structural stability analysis;The support condition and the shape of the member have little influence on the stability of the structure.Considering the first 10 buckling modes of the structure and using the initial imperfection value L/200 for analysis,the minimum stability bearing capacity of the structure can be obtained.The average value of the influence coefficient obtained by using the initial defect value L/200 is about 10%less than that obtained by using the initial defect value（L/300）recommended by the code.2.The stability bearing capacity of the structure considering double nonlinearity is about 56%of that considering only geometric nonlinearity.The formula for the calculation of the elastic-plastic stability bearing capacity of the structure q_cr=0.91（?）-1.97（initial defect value=L/300）and q_cr=0.53（?）+5.38（initial defect value=L/200）.Considering the initial defect value of L/300 and L/200,the stability factor of the roof is greater than the safety factor,which indicates that the structure has good stability performance.3.when 8 or more high sensitive members fail or 6 or more high sensitive nodes fail in a single area of the structure,the damaged structure is unstable and collapsed.When 8 or more high sensitive members fail in multiple areas of the structure or one or more high sensitive nodes fail,the structure will collapse.Strengthening 4-6 important members or strengthening 3-4 important nodes can markedly improve the collapse resistance of the structure.When the whole structure collapses,the proportion of plastic members is less than 0.93%.After strengthening 8 important members,the collapse resistance of the roof of the navigation hotel is improved markedly.