Static Nonlinear Analysis of New Space Structure -Composite Ribbed Shell

摘要

Composite ribbed shell is a new type of large-span space structure, which is consisted of thin concrete shell andrncomposite ribs. Compared with usual ribbed RC shell, composite ribs are made of steel slabs and concrete, wherernthree steel slabs are welded in a U section that concrete is cast in. Composite ribs are distributed along the sphericalrncurves just as the reticulated shell. This kind of new structure has many advantages, such as making full use ofrndifferent material characteristics of steel and concrete, and using the steel slab as the tensile steel reinforcement. Byrnusing the steel slabs as the framework to solve the problem of construction and removal of temporary formwork, itrncan reduce the construction time; compared with reticulated shell, this structure can slack the initial limitationrnsensitivity and increase the structure ultimate bearing capacity for the composite ribs existing; using the RC shell asrnroofs, composite ribbed shell has maintenance and decoration function, higher resistibility to wind and snow load.rnThe static mechanical characteristics and the influence factors of composite ribbed shell are mainly analyzed with arncomposite structure nonlinear finite element model in which 3-D beam element and higher 8-node curved shellrnelement are used. A new beam section of steel layers covering on 3-face of RC ribs is first proposed, arc-lengthrnmethod is used to trace the whole mechanical behavior, and membrane forces and axial forces are observed too.rnDifferent conditions such as height-span-ratio, boundary conditions, composite rib section dimension and differentrnloading are discussed; a comparison between composite ribbed shell and ribbed RC shell is made. It is found that:rnnonlinear bearing capacity is much smaller than that of linear one; as the height-span ratio value becoming larger andrnboundary condition more rigidity, the ultimate bearing capacity is greatly increased, while composite rib sectionrndimension has a negative influence. Form the comparison with ribbed RC shell, both the whole stiffness matrix andrnultimate bearing of composite ribbed shell are higher than ribbed RC shell for steel ribs existing, the membranernforces are distributed more reasonable too.