Analysis Of The Influence On Progressive Collapse Resistance Of Single-layer Latticed Domes Under Members Different Failure Conditions

As the global climate continues to change,the frequency of extreme weather events,such as blizzards,is increasing.It is easy to cause simultaneous failure(SIF)of multiple members connected to single-layer latticed domes joints under the action of rain and snow load or heavy snow and ice cover.If the initial damage area is small,the roof deformation of the reticulated shell structure will be caused by the failure of a single member,and the flow load will be generated in the rain and snow weather.It is also possible that the successive failure(SUF)of multiple members will eventually lead to the collapse of the whole structure or large-scale collapse.Therefore,in this paper,the dynamic response characteristics of single-layer latticed domes under different member failure conditions were studied in depth through the anti-continuous collapse dynamic test of K6 singlelayer latticed domes scale model,combined with numerical simulation and theoretical analysis methods.Specific contents and methods are as follows:(1)The anti-continuous collapse dynamic test of the scale model of K6 single-layer latticed domes was designed and carried out.The results showed that the collapse mode of the structure under the SUF condition was as follows: the structure gradually destroyed along with the force transmission path,the "spatial arching effect" failed,and local collapse was caused by the fall of regional nodes.The anti-continuous collapse mechanism is: the failure joints and connecting members are beam mechanism,and the remaining members are mostly compression mechanism.(2)The beam element B31 was selected to simulate the reticulated shell members,and the dynamic analysis of the continuous collapse process of the reticulated shell was carried out in combination with the function of ABAQUS "life and death unit".By comparing the dynamic response results of the structure,it is found that: compared with SUF condition,the dynamic response of the reticulated shell structure is more severe under the SIF condition.The two failure conditions show two different failure modes after increasing load,that is,the reticulated shell structure is more prone to continuous collapse under the SIF condition of local members.(3)In view of the conclusion that the dynamic response of reticulated shell structure is different under different failure conditions,the theoretical analysis was made from three perspectives: different loading paths,dynamic effects of single-degree of freedom system,and different load transfer modes under joint action of hingeless arches.The correctness of relevant theories was verified by the simple numerical example.(4)The nonlinear dynamic responses of three types of single-layer latticed domes(K6 type,TD type and rib ring oblique rod type)under different failure conditions were studied in this paper.Considering the influence of important parameters such as rise-span ratio and member section size,the deformation of the three types of reticulated shells under different working conditions can be divided into four failure modes: mode 1,both SUF and SIF conditions have local failures in the node area,and there is no significant difference in the final vertical displacement of the node;mode 2,local destruction of the node area occurred under both SUF and SIF condition,and the final vertical displacement of the node under SIF conditions was significantly larger;mode 3,the reticulated shell collapses locally under the SUF condition,while the whole reticulated shell collapses under the SIF condition;mode 4,the reticulated shell collapses as a whole under both SUF and SIF conditions.The load range corresponding to each failure mode under different member section sizes and rise-span ratios is given.By analyzing the dynamic responses of different types of reticulated shells under different failure conditions of members,the order of sensitivity of different reticulated shells to different failure conditions of members was obtained: K6 type > TD type > rib ring oblique rod type;In addition,the load-displacement curve can be used to determine the load-bearing capacity of the reticulated shells: TD type > K6 type > rib ring oblique rod type;deformation ability: K6 type > TD type > rib ring oblique rod type.