Unstressed State Control Method Applied In The Concrete Self-anchored Suspension

In recent decades, the raise and developing of the technology of bridge formed by stages makes great sense of bridge construction. According to scholars’ previous understanding, they have to consider the construction process to solve the final internal force and alignment of bridges formed by stages. They are unable carefully consider each construction stage, considering the complexity of cable-stayed bridge, arch bridge, suspension bridge, etc. Therefore, the conventional design method of bridge is not adapt to different construction method and process, which change the internal force and alignment during finished stage.The unstressed state control method which is put forward for bridge formed by stages improves the adaptability. With this method, the internal force and alignment will not change as long as the unstressed length and curvature remain unchanged. In this paper, the concrete self-anchored suspension bridge is studied in combination with unstressed state control method.First of all, this paper explains detailedly the two concepts: unstressed length&unstressed curvature in an easy-understandable way, which is put forward in the method. The mechanical equilibrium equation, which has slightly differences with the original derivation, for structure of bridge formed by stages is derived from the perspective of energy principle. These differences not only do not affect the understanding and application of the method, but can introduce and explain the two basic theories of unstressed state control method.Afterwards, this method is studied in detail with self-anchored suspension bridge by using midas Civil, which is a kind of finite element analysis software, on the basis of unstressed state control method. How to analyze the initial equilibrium state of self-anchored suspension bridge and solve the unstressed amount of bridge’s elements is introduced with this method. A new suspender tension method based on adjusting the unstressed length of suspender is presented. The possible errors and the adjustment in construction is introduced with this method.Finally, concrete shrinkage and creep effects which is a thorny problem in concrete self-anchored suspension bridge is studied in detail. This paper introduces the concrete shrinkage and creep and how to calculate this effects by using midas Civil. The shrinkage and creep in construction which has little effect of finished state. The long-term performance of the example bridge is evaluated and improved. A improved design method of self-anchored suspension bridge to reduce the internal force of the shrinkage and creep in girder is presented.