Study On Static And Dynamic Characteristics Of 600m Span UHPC Plate-Steel Truss Composite Arch Bridge

The development of construction in the central and western regions has also promoted the development of bridge construction,but the special geographical environment in the central and western regions makes it difficult for the development and research of large-span arch bridges to keep up with their construction requirements.In order to solve this problem,through the analysis of the development history and research status of arch bridges,this paper finds that the impact of the structural weight effect will increase sharply as the diameter of arch bridges increases,resulting in materials that are difficult to meet mechanical requirements,construction difficulties and construction costs.Therefore,mitigating the weight of the structure and the impact it brings becomes a key issue.How to reduce the weight of concrete arch bridges and the problems caused by them are mainly studied from three aspects:(1)the use of higher performance materials,(2)the optimization of structural forms,and(3)the improvement of construction methods.Through the analysis and summary of the development and research status of the above three aspects.In this paper,a new UHPC-steel belly rod combined arch bridge that integrates the advantages of materials,combined structure and prefabricated construction,and can be constructed by cable hoisting.And a corresponding preliminary analysis was made:(1)The test design of the 600 m span class arch bridge in Japan is taken as the engineering background.The static analysis of the new UHPC-steel belly rod combined arch bridge was carried out systematically.The results show that the new structure meets the specification requirements in terms of strength,stiffness and stability.At the same time,compared with the original RPC arch bridge,not only the internal force of the structure is greatly reduced,but the number of construction is also significantly reduced.This shows that the force of the new structure is feasible.(2)The construction of the arch bridge is also a key in the design and construction.Through the comparison of the stress characteristics of the new structure and the construction methods,the new structure is proposed to adopt the construction method of cable hoisting.This paper simulates the whole process of hoisting construction of the main arch ring.Explore the structural stress performance of the new structure during construction and the stability of the section hoisting process.The results show that due to the optimization of the material and structural form of the new design,the weight of the hoisting section is effectively reduced,so that the clamping rope force,UHPC top bottom plate and steel belly rod stress state during construction are within the allowable range,and the stability during construction also meets the corresponding specifications.Preliminary analysis shows that it is feasible for the new structure to be constructed using prefabricated assembly.(3)The stiffness and quality of the new structure have changed.In order to explore the dynamic characteristics of the new structure,the RPC arch bridge and the new structure dynamic model were established.The analysis shows that the self-resonance frequency of the new structure is lower than that of the RPC arch bridge,and its stiffness is slightly reduced compared with the cross-section of the RPC box girder.(4)At the same time,the time history analysis of the arch bridge of the two structural forms was carried out,and the dynamic response of the structure under the action of three-way seismic action of the two was compared.The results show that the seismic performance of the new structure is better than that of RPC arch bridge in both transverse and longitudinal aspects.And add two-way seismic analysis to compare the effects of vertical earthquakes on arch bridges of two structures.It is found that vertical earthquakes will increase the internal forces and displacements of the two structures in the arch bridge deck to a certain extent,but the increase of the new structure is less than that of the RPC arch bridge,indicating that the new structure is better than the RPC arch bridge in terms of vertical seismic performance.