Study On Key Construction Technology Of Long-span Steel Concrete Composite Cable-Stayed Bridge Across The Yellow River

With the rapid development of large-span highway bridges,various types of bridge structures have been innovated.Combined the advantages of steel and concrete bridge structures,steel-concrete composite cable-stayed bridges gradually become the main type of bridge structures in China today.However,modern cable-stayed bridges belong to high-order statically indeterminate structures,which are difficult to construct.Therefore,how to choose the appropriate construction scheme,accurately calculate the cable forces at all stages of construction,and monitor and control the bridge in real time are all particularly important to ensure the construction safety,and to close the state of the bridge after construction with the preset state of reasonable completion.Based on the Qinglan Line Pingyin Yellow River Bridge,the key construction technology of steel-concrete composite cable-stayed bridges in complex environments are systematically studied,including key technologies of steel box girder transportation,steel box girder installation in tower sections and load bearing sections,bridge deck installation,and beam construction control.The main research is as follows:(1)Lifting and transportation of steel box girder.The beam transportation method of the bridge crane with rotating mechanism combining the flat beam truck is proposed and designed,which effectively solved the steel box girder lifting problem,and circumvented the difficulty of transporting in special watersheds.This method provides broad application prospects,having high construction efficiency and safety.(2)Lifting technology of bridge deck.The bridge deck transportation and installation technology of half-arm hanger combing single cantilever gantry crane is proposed and designed,which solved the inconvenient installation problem of high-quality prefabricated plates at high altitude.This method is safe,efficient and accurate,having great reference value for the same type of bridges.(3)Sliding in place method of steel box girder.The required steel box girder brackets are firstly designed and installed.Then the longitudinal movement of the steel box girder is realized by the tank wheel sliding system with independent design,after the two car cranes hoist the steel box girder to the designated position.Finally,the jack is precisely positioned to complete the installation The method has solved thesteel box girder installation difficulty in tower area beam section and the side span beam section,which is worthy of promotion.(4)Construction control of main beam.The calculation and analysis of the whole bridge construction process based on Midas/civil,combined with the field measured data are carried out to ensure the safety of the main bridge construction and the successful completion for close.Also it is effectively ensured that the main tower will not deviate after the bridge is completed,and the main beam is reasonably stressed.This study has effectively solved the key technical problems in the construction of Pingyin Yellow River Bridge of the Qinglan Expressway using steel-concrete composite cable-stayed structural type.The technical solutions and innovative methods proposed in this paper will provide certain support for the efficient construction safety of the same type of steel-concrete composite cable-stayed bridge in complex environment.