Research On Main Arch Ring Structure Of Long Span Cantilever Concrete Arch Bridge

Cantilever casting method is a widely used method for long-span concrete bridges in China at present,and it is also a construction method with relatively mature construction experience.The reinforced concrete arch bridge constructed by cantilever casting method has good structural stability,strong adaptability to geology,less late maintenance costs,and good component durability,which is especially suitable for mountainous areas without construction sites.However,due to the increasing span of arch bridge,the weight and section stress of arch ring segment also increase,which also improves the bearing capacity requirements of anchor system,and the restrictions on arch ring alignment and location also need to be more strict.Therefore,in order to meet the structural stress and reduce the weight of bridge segments,and improve the bridge span,this paper,relying on Shuiluohe Bridge,has carried out the research and development of key technologies for the main arch ring structure and construction of long-span cantilever reinforced concrete arch bridge.The main research contents are as follows:(1)The elastic thin plate theory and the equivalent compression bar theory of the arch are adopted,and the calculation formulas for the critical height,critical width and critical plate thickness of the main arch ring of the concrete structure arch bridge are derived based on the reasonable failure order of the arch.The accuracy of the formulas is proved by using the numerical analysis method,which provides a theoretical basis for the design of the arch ring of the long-span concrete structure arch bridge.(2)The control variable method is used to analyze the influence of the arch ring size on the critical stress of the arch ring,and a box section with longitudinal ribs is designed for the arch ring of the arch bridge section with large dead weight and poor local stability of the top,bottom and web of the single box and single room section.According to the mechanical characteristics between the top and bottom plate and the web of the arch ring,the feasibility of this concept is proved by theoretical derivation and numerical analysis.(3)A new type of section with longitudinal ribs corresponding to Shuiluohe Bridge is proposed.At the same time,the design parameters such as rise span ratio,arch axis coefficient and arch building form are analyzed.The full bridge bearing capacity test,stability check calculation and comparative analysis of structural dynamic characteristics are carried out according to the current design specifications.(4)Carry out the cantilever pouring construction analysis of Shuiluohe Bridge with original section and new section with longitudinal rib,use the stress control method to calculate the arch ring stress of the main arch ring in the whole construction process,compare and analyze the stress characteristics of the new box section with longitudinal rib and the original section in the whole pouring construction process,and then verify the rationality of the box section with longitudinal rib.