Mechanic Behavior Analysis And Constrution Control In The Bow-string Continuous Beam-arch Composite Bridge With A Special Shaped Arch

Qingyang Bridge is a bow-string continuous beam-arch composite bridge with a special shaped arch of a30+80+30-meter span, which steps over Jinjiang River in Shanggao county of Jiangxi province. The connection beam of variable height is a pre-stressed concrete single box girder with six cells. This paper aims to analyze the strength, the stiffness and stability of the bridge in the whole construction of the upper structure and the operation phase as well. Meanwhile, this paper also expounds the construction monitoring of the bridge. The main results of this project include the following six parts:1. Forward-calculation method is employed to make a simulated analysis of the entire construction process of the bridge superstructure, thus the deformation and stress of each construction stage could be obtained, which provides the construction control of Qingyang Bridge with a data reference.2. A variety of tensioned program and final tension value are analyzed and compared, which is available to propose two tension programs. The tension sequence and final tension value are finally disclosed.3. Differences in the mechanical performance of beam and arch that are caused by the arch rib height gap of both sides are explored through the analysis and comparison of the plane and space of Qingyang Bridge. Accordingly it can be concluded that the place model is suitable for Qingyang Bridge instead of the plane model as the low arch axis force is about20percent higher than the high arch.4. The analysis results of the strength and stability of the Qingyang Bridge in the operation phase demonstrate that the connection beam, arch rib and boom all meet the strength requirements and the structure force is reasonable and structural stability is adequate as The first four order stability coefficient of the arch rib exceeds the specification of4-5under the coefficient main and additional forces.5. Stress analysis on the foot position of the beam arch junction is conducted, the result of which manifests that strength in foot position meets the strength requirement in the operation phase and its stress calculations are in good agreement with the measured values.6. Construction monitoring is finally completed. The displacement and the measured values are consistent with the theoretical values. The measured cable force is close to the design value and complied with the design specification.