Effect Of Initial Defect And Load-transfered Path On The Progressive Collapse Resistance Of K6 Single-layer Latticed Dome

In this paper,the dynamic test of K6 single-layer latticed dome structure is carried out,and the influence of the initial geometric defect and the failure mode of transmission path on the progressive collapse resistance of the structure is studied by numerical simulation technology.The main research contents and conclusions are as follows:(1)The collapse mechanism of K6 single-layer latticed dome is studied through the dynamic removed members test: when the progressive collapse occurs,the collapse mechanism of K6 single-layer latticed dome is compression mechanism.Compared with the beam mechanism in the process of collapse,the compression mechanism can make better use of the characteristics of the material itself,give full play to the compressive properties of the material,and greatly develop the potential of the material,so as to effectively enhance the progressive collapse resistance of the whole structure.(2)Analyzes the causes of the progressive collapse of the structure: through the analysis of three K6 latticed domes ant-progressive collapse,it can be known that before the progressive collapse of the whole structure,the whole structure can quickly adjust the dynamic response and internal force change caused by the local failure,so that the latticed dome regained stability.However,when the residual structure cannot quickly complete the adjustment of local internal force redistribution,the local collapse begins to expand outward gradually,and the redistribution of internal force of the whole structure fails,resulting in the occurrence of progressive collapse of the whole structure.Therefore,it is an important reason that the residual structure fails to adjust the redistribution of local internal force in time.(3)Dynamic analysis of a large number of numerical models shows that K6 latticed dome is defect-sensitive structure with similar discrete eigenvalue problem.The effect of geometric initial defects on the progressive collapse of the structure is not limited to the first-order buckling mode defect configuration.Considering the reduction of the probability of high-order modes,it is found that the 1-10 order buckling modes are recommended to be taken as the defect configurations in the design of K6 latticed dome structure.(4)The influence of different transmission path failure conditions on the progressive collapse of structures is analyzed.Through numerical model analysis of the structure under different load transmission path failure conditions,it can be known that the order of the possible working conditions that cause the structure to undergo progressive collapse is: SJ-1 <SJ-2 <SJ-3.The main reason is that when two force transmission paths fail at the same time,the dynamic response to the structure is greater,resulting in the local internal force redistribution of the structure cannot be adjusted in time,the local collapse continues to develop outwards,and eventually progressive collapse of the structure.The single-layer latticed dome is completely flipped.(5)Based on the above analysis,the full-scale model is designed to strengthen the progressive collapse resistance.Firstly,the structural members are divided into three types: radial members,circumferential members and diagonal members,and then the above three types of members are strengthened respectively.The analysis results show that the order of significance in improving the performance of the structure antprogressive collapse is: partial diagonal members > partial circumferential members >radial members.From further analysis,we can see that when the radial members,the 3-ring ring members,the 4-ring ring members,the 3-ring diagonal members and the 4-ring diagonal members are strengthened at the same time,the effect of improving the progressive collapse resistance of the structure is optimal.