强震作用下巨型网格结构的抗倒塌性能研究

Study of collapse behavior of huge reticulated structure under strong earthquakes

选取圆柱面巨型网格结构为研究对象,在强震作用下,以结构的最大节点位移和杆件失效的数量以及分布作为判别标准,利用ANSYS/LS-DYNA有限元分析软件采用增量动力分析法对结构进行倒塌过程分析,研究结构的倒塌失效机理.在一系列地震波的调幅作用下通过对结构的响应分析可知,结构的倒塌是属于由几何非线性起主导作用的动力失稳倒塌.由倒塌过程中杆件失效的顺序可知,首先失效的杆件发生在支座处的上弦杆与下弦杆,然后向周边扩散至纵向桁架与拱向桁架相交网格的杆件.基于空间结构节点刚度的两种假设,即刚接和铰接,给出了节点刚度对圆柱面巨型网格结构抗倒塌性能的定量分析.结果表明,节点刚度对结构抗倒塌能力的影响较小,按照铰接节点设计圆柱面巨型网格结构是偏保守且合理的.

The cylindrical reticulated mega-structure is selected,under the action of strong earthquake,to research the collapse behavior based on the measurements the maximum node displacement and the number and distribution of the failure of the rod are taken as the criteria for judging.Finite element analysis software ANSYS/LS-DYNA is used to analyze the collapse process of the structure with incremental dynamic analysis method,and the collapse failure mechanism of the structure is studied.Under the action of amplitude modulation of a series of seismic waves,it can be seen from the response analysis of the structure that the collapse of the structure is a dynamic instability collapse dominated by geometric nonlinearity.It can be seen from the failure sequence of the bars in the collapse process that,first,the failure bars occurred at the upper chord and lower chord of the support,and then the failure bars diffused to the intersecting grid of the longitudinal truss adjacent to the support and the arch truss.Based on two existing assumptions about the stiffness of joints of spatial structures,namely rigid joints and articulated joints,the quantitative analysis of the stiffness of joints on the collapse resistance of cylindrical mega-grid structures is presented.Results show that the stiffness of the joints has little influence on the collapse resistance of the structure.