Research On Mechanical Properties Of Prestressed Reticulated Mega-structure With Internal Cables

With the development of society,human beings put forward higher requirements for long-span spatial structure.The prestressed reticulated mega-structure has the advantages of strong spanning capacity,superior mechanical performance and elegant appearance,which well meets the demands of long-span spatial structure.However,most of the existing prestressed reticulated mega-structure are prestressed by arranging cables and struts outside the three-dimension(3D)truss structure.This arrangement involves the stability of struts,and the external cable arrangement has adverse effects on space utilazation and structural maintenance.In order to solve the above peoblems,our research group proposes a kind of prestressed reticulated mega-structure with internal cables,which applied prestress by arranging cab les inside the three-dimension truss beam.For this structure,this article has carried out a systematic research,such as the arrangement types of cables,the static performance,the mechanical properties of key joints and the simplified calculation method.The main research contents are as follows :(1)In view of the 3D-trussed arch is the main force parts of the reticulated mega-structure.This paper proposes eight arrangement types of cables in the3D-trussed arch,and the static and stability performance of 3D-trussed arch under different arrangement types of cables are compared and anal yzed in order to prefer the best one for the overall structure.(2)The optimal arrangement type of cables that suitable for 3D-trussed arch is introduced into reticulated mega-structure,and two schemes of arrangement types of cables are proposed.By comparing the static performance of the structure under two schemes,the optimal arrangement types of cables suitable for cylindrical reticulated mega-structure is obtained.Based on this,the influences of rise-span ratio,height of three-dimension truss beam,section size of chord of main structure,the size and distribution of prestressing force of cables on structural static performance are studied.(3)The key joints of the prestressed reticulated mega-structure with internal cables are studied.For the three-direction joint of cable,the influence of angle C of corner cable on the mechanical behavior of triangular node plate and the steel consumption for structure is studied.For the lower chord cable joint,its mechanical properties of the overall structure are investigated,and the ultimate bearing capacity of the lower chord cable joint is analyzed in detail.According to the failure mode of the joint,the strengthening measures are put forward.Then,the calculation formula of its bearing capacity is deduced.(4)Taking the three-dimension truss element with internal cables from the whole structure as the research object,the theoretical calculation method of its deflection is proposed.The stiffness of the three-dimension truss with internal cables is studied,and the influence of the cable section area and the height-span ratio of the three-dimension truss on the stiffness improvement effect is analyzed.According to the variation law,the expression of the vertical bending stiffness and the shear stiffness improvement coefficient is proposed,and the mathematical tool mat lab is used for fitting,and its accuracy is verified.Finally,the applicability of the simplified deflection and the stiffness calculation method in the overall structure is verified.