Study On Main Arch Structures And Mechanical Performances Of Yelanghu Bridge

The development of long-span arch bridge is linked closely with the construction technique. Concrete material with low tensile strength and high pressure strength is suitable for arch bridge.The construction is difficult with increase of the span.The method of Cantilevered-casting and the combined technique with Cantilevered-casting and Stiff-skeleton are used for arch bridge construction in abroad. There is still a large gap between China and the foreign countries both in construction experience and design theory.This study relies on technology projects "Research on the Main Arch Structures and Mechanical Performances with Single box and cell" in "The Key Technology and Demonstration of the Combined Technique with Cantilevered-casting and Stiff-skeleton" in Guizhou province. The Yelanghu Bridge lack of similar design firstly use single box and cell in long-span arch.The studies of Yelanghu Bridge are as follow in this thesis:① Based on the theory of elastic thin plate and equivalent compressive column of arch, the objective is to study the suitable structures in the combined technique with Cantilevered-casting and Stiff-skeleton, and to deduce the thickness formula in critical state that the stress of the local buckling equal to it of overall buckling and determine the destruction order at critical ratio between thickness and width (ξ=t/b).② The studies of the section types of single box with single-cell,double-cell and three-cell show that single box and single cell has a strong ability to resist out-of-plane buckling. With the number of cells decrease,top and bottom plates of arch section become risky.the flange to be set can reduce critical thickness in local buckling state.③ The influence rule of skeleton structures and length fuction on arch stiffness is studied by numerical analysis.And equivalent stiffness of the main arch with skeleton is deduced by energy method.The results show that equivalent stiffness distribution is most smooth when the strength of skeleton about half of span.The stiffness effect in compound section is analyzed by principle of equivalent stiffness.Skeleton structures have little effect on internal forces, deformation, dynamic performance and stability.④ The construction stability analysis of Yelanghu Bridge is carried out.Meanwhile it considers the influence of temperature.