Analysis Of Staic Stability And Dynamic Response For Crossways Beam String Structures

Beam String Structure,which is a reasonable self-balanced structural system composed of the string,stut and arch,has wide application prospect.Based on the published articles,by using the FEM software ANSYS the static behaviors,static stability and dynamic response under earthquake of crossways beam string structres are studied in this paper.The main contents are summarized as follows:(1)Self-balancing Cables Forces Ratio Method is adopted to research the prestressdetermining method of crossways beam string structure and to verify the determination method based on example.On that basis,the crossways beam string structure and the static performance of its corresponding single-layer latticed shell is compared and analyzed.are investigated respectively by considering changes of the rise-to-span ratio of upper cord and half-span distribution of live load.The results show that Self-balancing Cable Force Ratio Method is high in computational accuracy and easy solving process,which is applicable to determining the cable prestressing of crossways beam string structure.The lower cable-strut system after introduction can effectively reduce the internal force peak and deformation of upper cord and magnify the structural stiffness.When the structural depth-span ratio keeps unchanged,with the increase of upper cord rise-span ratio,the node's vertical displacement and unit's internal force don't differ significantly.The half-span distribution of live load is unfavorable to the vertical displacement of node for structure.In the engineering practice,the rise-span ratio of upper cord is suggested to be 0.06,and the influence of half-span distribution of live load is considered.(2)In consideration of the introduction method of different overall initial geometric defects,the static stability of crossways beam string structure is analyzed,with parameters changed to discuss the impact of upper cord's rise-span ratio,half-span distribution of live load,maximum initial geometrical defect value.on structural stability performance.Studies have shown that compared with the random imperfection mode method and modified eigenvalue imperfection mode method,the consistent imperfection mode method based on nonlinear buckling mode is high in computational efficiency,and the calculation result is more unfavorable to the modified eigenvalue imperfection mode method.It is suggested to introduce the overall initial geometric defects of structure in the consistent imperfection mode method.When depth-span ratio of structure is determined,the stability coefficients of bearing capacity obtained from analysis of different rise-span ratios of upper cord have little difference.The risespan ratio of upper cord is reasonable when valuing 0.06.The maximum integral initial geometric defects influence the stability bearing capacity of the structure significantly and it is suggested that the maximum defect value is 1/300 of span.The half-span distribution of live load is more unfavorable to the stability coefficients of bearing capacity of the structure.(3)The time-history method is adopted and different introduction methods of seismic wave are considered to research the crossways beam string structure's dynamic response to under earthquake,and the impact of change of parameters such as the rise-span ratio of upper cord,Initial geometric imperfection,amplitude modulation ratio of earthquake intensity.The research shows the following Compared with the frequent earthquake,the under earthquake is more unfavorable to the dynamic response in the overall consensus method,and the structural deformation is more significant than the increasing amplitude of unit's internal force.Based on the analysis results and the relevant specification requirements,the overall consensus method shall be adopted to analyze the dynamic response of crossways beam string.Considering the support large mass method can simulate the possible looseness of lower cable,support large mass method can be adopted to supplement the analysis of dynamic response.The decrease of rise-span ratio of upper cord weakens the structural stiffness.Compared with the maximum axial force of unit,the maximum nodal displacement has great decreasing amplitude in under earthquake.Overall initial geometric defects generate significant impact on the structure's dynamic response.The dynamic response of structure is most unfavorable under equal proportion amplitude modulation.