Broken Cable Analysis Of Prestressed Giant Grid Structures With Different Cable Types

The cable prestressed cylindrical giant grid structure is composed of an upper giant grid structure and a lower prestressed cable system.The upper giant grid structure has clear force transmission,various forms,and convenient construction.The lower prestressed cable system can effectively improve the structural rigidity,reduce the cross-section of the rod,and reduce the amount of steel used.As a new type of prestressed long-span structure,a lot of research and analysis have been conducted on the structural shape,mechanical properties,calculation methods,optimization analysis,etc.of this structure at home and abroad,but there are few studies on the impact of the lower cable network breaking.In recent years,the continuous collapse performance of structures has received more and more attention.Therefore,it is very necessary to study the impact of the breakage of the lower part of this new type of structural system on the overall structure.Based on the finite element theory,this paper uses the large-scale finite element analysis software ANSYS to carry out the parametric modeling of the cable prestressed cylindrical giant grid structure and the numerical simulation of the cable breakage using the element life and death method.Study the influence of the local broken cable on the structural displacement and the internal force of the rod.It is clear that the cable breakage at different positions has different effects on the overall rigidity of the cable prestressed cylindrical giant grid structure,and the effect of local breakage of different cable types on the key members and displacement of the upper giant grid structure is studied.On this basis,by changing the relevant parameters to explore the difference in the influence of local broken cables on the structure,a general conclusion about the influence of local broken cables is obtained.The conclusions drawn by this article through a large number of numerical simulations are as follows :(1)The morphological analysis of the cable prestressed giant grid structure was carried out.According to the morphological analysis theory of the prestressed reticulated shell structure,the morphological analysis of the two pre-stressed cable prestressed giant grid structures was carried out.The geometry and initial defects of the cable rod in the prestressed lofting state.Through variable parameter analysis of prestress size,strut length,vector-span ratio,and structural span,the study shows that it is necessary to perform morphological analysis of the structure under various parameters.(2)The spherical arc length method is used to track and analyze the structural stress after the cables at different positions exit the work.The effects of local cable breakage on structural stiffness,cables,and members in different positions of the upper giant grid structure were explored.The analysis compares the stress condition of each member under the condition that the structure continues to bear to normal use before and after the broken cable and the difference of the influence of the broken cable on the different types of cable.Discuss the effect of broken mid-span cables on the overall displacement of the structure under different prestress sizes,strut lengths,vector-span ratios and structural spans.Studies have shown that the greater the prestress,the longer the length of the strut,the smaller the span,and the greater the ratio of the span to the lower the impact of the broken cable on the structure.(3)Using the instantaneous dynamic method,the instantaneous dynamic response of the broken cable to the structure was explored.The characteristics of the dynamic response of the displacement of the upper giant grid structure and the key members of the upper cable lattice at the mid-span and end of the different cable modes are analyzed and compared,and the ratios of the dynamic and static solutions of the nodes and members are given.The dynamic response of local broken cables to the structure under different prestress sizes,strut lengths,vector-span ratios and structural spans is investigated.Studies have shown that the dynamic response of the structure after the cable breaks continuously with the increase of prestress,span and vector-span ratio Enhanced.The length of the brace has no significant effect on the dynamic response of the structure after breaking the cable.