Theoretical Analysis And Experimental Study On The Long-Span Steel-Box Stacked Arch Bridge Of High-Speed Railway

With the continuous development of the design theory and the construction technology of bridge engineering, safety and applicability are not the only main factors to consider in design, and the aesthetic quality of the bridge becomes active demand of times. Possessing the advantages of strong span ability, high stiffness, attractive appearance, big clearance under bridge and so on, stacked arch bridge has been applied in high-speed railway bridges. Stacked arch bridge is a new arch system, in which parts of the arch rib is separated into upper and lower arch rib and their skewbacks are fixed on a same pier or different piers. In this paper, the domestic and foreign development and research results of long-span steel arch bridges are summarized, and based on Xinkai River Bridge on Harbin-Dalian high-speed railway, systematic study of the structure of high-speed railway steel-box stacked arch bridge is made, including mechanical performance, experimental test, and safety assessment of corrosion-damaged suspenders. The main work and conclusions are as follows:Firstly, cooperation mechanism between beam and arch ribs of the new stacked arch bridge structure system and its simplified calculating method are studied. After inductive analysis of FEA result of suspenders and connection rods of stacked arch bridge under uniform distributed loads, internal forces of suspenders and connection rods are assumed to be respectively equal and treated as membrane tensions, and stacked arch bridge structure is divided into beam-arch, suspenders and connection rods. Based on the deformation coordination equation, the expressions of membrane tensions and the deflection of beam are solved.Secondly, the complete study of the structure of high-speed railway steel-box stacked arch bridge is carried out. Taken Xinkai River Bridge on Harbin-Dalian high-speed railway as case study, mechanics behavior of static and dynamic force and stability performance of steel-box stacked arch bridge are calculated, and effects of structure design parameters on structure mechanical behavior is analyzed, such as rise-span ratio, leaning angle of arch rib, layout of crossbars, layout of suspenders and rigidity ratio of arch rib to beam. Based on the improved response surface method, the reliability of rotation angle at beam end of high-speed railway steel-box stacked arch bridge is assessed.Thirdly, combining with experimental test of Xinkai River Bridge, structure of high-speed railway steel-box stacked arch bridge under each construction stage is calculated. Optimal control tension of suspenders and internal force and displacements of arch bridges is analyzed to meet the design requirements by adopting the backward analysis method which improves the construction control precision. Due to the experimental test for construction stages, the safety of the construction is ensured and favorable conditions for further analysis and research is created.Finally, effects of corrosion-damaged suspenders on the static and dynamic mechanical behavior and stability are analyzed. Based on the interval reliability theory, different corrosion-damaged failure modes are established to analyze the interval reliability of the steel component, which indicates that the reliability analysis of corrosion-damaged steel structure based on interval reliability theory is more objective and comprehensive in the safety assessment of existing steel structures. The structure safety performance of Xinkai River Bridge in operation stage is calculated and analyzed based on the corrosion-damaged suspender model.The structure system, structural parameters, simplified calculation, experimental test and structural safety assessment of corrosion-damaged suspender of high-speed railway steel-box stacked arch bridge are systematically analyzed and researched in this paper, which would provide the basis and reference for the design, construction and operation stages of stacked arch bridge.