Research On The Dynamic Response And Failure Mechanism Of Kiewitt6 Single-layer Reticulated Shell Structure Supported On The Lower Part Of The Large-span Under Impact Load

As one of the representatives of the large-span spatial structure,the reticulated shell structure is favored by the public because of its characteristics such as high rigidity,reasonable stress,light weight and beautiful appearance.It is widely used in some large or medium-sized public buildings and landmark buildings,such as museums,exhibition halls,stadiums,opera houses,etc.However,in recent years,the failure of buildings with large-span spatial structures under accidental impact collision loads such as terrorist attacks,aircraft impacts,wartime shells,and missiles has been common.Many experts and scholars have done a lot of related research on such scientific research issues and achieved certain results.However,the previous research objects are basically singlelayer reticulated shell structures,but in real life,most of the reticulated shell structures have lower supporting structures.Therefore,this paper takes Kiewitt6 single-layer reticulated shell structure with lower supporting columns as the research object,analyzes the factors that have not been considered in previous scientific research results from a new research perspective,and studies its dynamic response and failure mode under impact load.The research content can be summarized as follows:(1)Comparing the test data with the ANSYS / LS-DYNA finite element numerical simulation through the landing Kiewitt6 single-layer reticulated shell dynamic response test to prove the accuracy of the ANSYS / LS-DYNA finite element numerical simulation.The dynamic response of the floor-standing Kiewitt6 single-layer reticulated shell structure and the Kiewitt6 single-layer reticulated shell structure with lower supporting columns under impact load was compared.Then change the outer diameter and wall thickness of the upper lattice shell rib bar,ring bar and diagonal bar,and analyze the dynamic response of the overall structure from the three aspects of the vertical displacement of the specified bar,the kinetic energy of each bar,and the strain energy of each bar,and Compare the analysis results of the three members.Change the span and sagittal ratio of the upper reticulated shell under the same impact conditions,and analyze the dynamic response of the whole structure from the aspects of the effective plastic strain of the specified member and the acceleration of the member.(2)Derivation of the rigid-plastic and elasto-plastic ideal models through the theory of the total energy of the structure under the action of static and dynamic forces.And it analyzes three different stages of its dynamic response,and the different stages are closely related to the impact load parameters.Then the energy method is used to theoretically derive the impact dynamic response of the lower support column,and compared with the numerical simulation results to prove the accuracy of the ANSYS /LS-DYNA finite element numerical simulation results.(3)By changing the impact angle,the height of the lower support column and the form of the lower support,the dynamic response of the overall structure is analyzed from three aspects: the horizontal displacement of the designated node,the stress of each member of the structure and the strain energy of each member of the structure.The analysis shows that the most unfavorable impact angle is in the range of 30 °-40 ° and the dynamic response of the lower support column at different heights when impacted.And the different forms of lower support have a great influence on the stability of the structure.The four methods of overall structural reinforcement,global reinforcement of the reticulated shell,reinforcement of the lower support column,and local reinforcement of the reticulated shell are compared,and the most economically feasible reinforcement method is analyzed.(4)A large number of ANSYS / LS-DYNA finite element simulations of Kiewitt6single-layer reticulated shell structure with lower support columns.According to its final failure deformation characteristics,ten failure modes of Kiewitt6 single-layer reticulated shell structure with lower supporting column under impact load are defined.Change the number and location of impact loads,and analyze the failure mode and dynamic response of the whole structure under impact loads from two aspects: impact kinetic energy and kinetic energy of each member of the structure.According to the structural stress cloud diagram,the failure mechanism of the structure is analyzed from the perspective of energy.