Research On Static And Stability Of 800m Super-large Span Kiewitt Type Mega-Latticed Suspend-dome

At present,super-span structures have been extensively applied to construct space bases,polar transit areas,Noah’s Ark,super stadiums,urban domes,etc.The proposal of super-span structures provides new ideas for future building constructions.The evolution from rigid,flexible to rigid-flexible hybrid systems provides a theoretical basis for the production of the super-span structure.In this paper,with reference to the superiority of the rigid-flexible hybrid system,the 800m super-large span kiewitt type mega-latticed suspend-dome is studied.The suspend-dome consists of three parts:the upper net shell,the cable system and the strut system.In order to enhance the rigidity and stability of the cable and strut system,the concept of truss-strut is proposed.Herein,the strut system is transformed into the truss-strut system,which improves the instability and stiffness of the struts.Compared with the existing research system,it is found that the truss can reduce the steel consumption while maintaining the bearing capacity,and the overall amount of compression is small to meet the stiffness requirements.The stability analysis of the fourth ring truss-strut system is carried out.The stability bearing capacity can satisfy the requirements of the codes.It is also recommended to use truss-strut systems in the 800m suspend-dome instead of the original strut system.In the static analysis,it is found that the full ring form and diagonal-brace of suspend-dome is not a reasonable structural scheme for 800m-span structures by comparisons of the super-large span kiewitt type mega-latticed suspend-domes with different numbers of cables.It is preferred to cancel the innermost ring or the innermost two rings cable support system.The increase of the cable of the innermost ring of the super-large span suspend-dome does not reduce the deflection of the overall structure and may have a negative impact.A general prestress solution method for the suspend-dome is proposed:the prestressed influence matrix method.This method can directly determine the prestress distribution and prestress level.This paper is a deep reflection on the suspend-dome.And then this paper proposes two new structure forms of super-large span suspend-domes,Extended Support Suspend-Dome（ESD）and Cable-Stayed Suspend-Dome（CSD）.The aim is to mitigate the side effects resulting from the size effect within the suspend-dome as span increases.Modeling and solving with ANSYS,it is found that ESD improves the space form of the sling system and the foundation,reduces the steel quantity,and facilitates calculation and construction.CSD combines the advantages of the cable form and the suspend form and has a beautiful shape and a reasonable force transmission path.This paper does deep optimization for the single truss.This paper proposes the Similar Super Element Method（SSM）,an effective single truss optimization method,to analyze suspend-domes.Comparing with the traditional full-stress selection method,it was found that SSM satisfies the deflection limit and can reduce the steel consumption.The stability analysis of the super-large span suspend-dome is carried out,and the first 13 orders of buckling modes of the super-large-span suspend structure are extracted.It is concluded that the buckling mode distribution of the suspend-dome is dense and the buckling characteristic values are close.In this paper,the"reverse pushing method"is used to analyze the mechanical performance of structures with different buckling modes as initial imperfections and the corresponding load-displacement curves are obtained.It is found that the worst happens when the initial defect is L/300 times of the 12^th-order buckling mode.Different from the original consistent defect mode method,the worst instability mode has arbitrariness,which is inconsistent with the“consistent defect mode method”in current codes.Therefore,it is recommended that the codes revise the stability provisions of the super-large span structure.