Stability Analysis Of Ellipsoid Steel-Concrete Composite Ribbed Shell

Steel-concrete composite ribbed shell is a new kind of space structure for enclosing large spaces.This kind of shell is made of composite rib and concrete shell:steel rib is formed by three thin steel plates welded in U shape,then concrete is poured to build composite ribs;those composite ribs are used as the formworks to make RC shell, finally the whole composite ribbed shell is completed.During the whole construction process,the founded members are used as the formworks and brackets to the latter.The new structure retains all the benefits of thin concrete shells,while eliminates the need for temporary formwork and minimises the required falsework,declines construction cost,so it is a kind of spatial structural system with good developing prospect.Instability is a main form of structural damage for long-span space structure.The specifications about long-span space structure.The design and calculation of space structure whose surface is elliptical surface are not stated explicitly or in detail by the specifications about long-span space structure.In this paper,stability of ellipsoid steel-concrete composite ribbed shell was studied in detail.The main content is described as follows:(1) In this paper,the development of long-span space structure during the past decades is introduced systematically,the weakness of traditional reinforced concrete shell is discovered,and the advantages,present situation and development of steel-concrete composite ribbed shell which is a new kind space structure are also summarized. (2) The static and eigenvalue buckling analysis of ellipsoid steel-concrete composite ribbed shell are executed with ANSYS software.Statical character and the characteristics when losing the stability in ideal status are studied preliminarily.(3) By analyzing the large-scale geometric parameters,the nonlinear stability of ellipsoid steel-concrete composite ribbed shell was studied.In order to grasp the bearing critical load and instable area distribution,a great deal of parameter analysis of influence factors are made,which including the size of composite rib,the thickness of reinforced concrete shell,the rise-span ratio,the ratio of short span and length span,all of the conclusions can be consulted to new structure design.(4) In this paper,the effect of boundary condition and initial imperfection on the stability of steel-concrete composite ribbed shell is also studied deeply.