The Key Construction Technology Researches On The Girder Of The Curved Extradosed Bridge With A Wide Deck

Extradosed cable--stayed bridge, also known as cable--stayed bridge, is a new type of bridge emerged in the last century and combined the advantage of ordinary cable — stayed bridge and continuous bridge. With the span range of 250 meters, cable-stayed bridge has the advantages such as excellent structure performance, pretty good economic indexes, elegant appearance and so on, and all those make it have strong competition in the building of highways and railways in urban areas and the model selection of municipal bridge. As the extradosed cable — stayed bridge’s force characteristics are similar to the long span prestressed concrete continuous beam bridges, they are usually constructed by the cantilever concreting (Cradle scaffolding) in construction site; besides, the main lower tower of the extradosed cable--stayed bridge makes its stay cable’s axial pressure on girder much higher than ordinary extradosed cable--stayed bridge, so the construction’s integral rigidity is generally larger, which lead to the wideness of the box girder cross section and the complexity of the girder construction technology.Based on the construction of Dazheng Gang extradosed cable — stayed bridge, the author conducts a full-bridge modeling analysis with the use of special analysis software for bridge-Midas/Civil and mainly focuses on the optimal research on the three key construction technology of the girder. The main research results are as follows:1.With the finite element software Midas/Civil, the internal forces distribution under the longest cantilevered stage among the four temporal consolidation schemes are analyzed and compared. The results show that the set of temporary bearing has great influence on the internal forces of the girder, and a reasonable arrangement will substantially improve the safety and reliability of the girder cantilever cast-in-place construction.2.Through the simulation analysis of moving way of the hanging basket, the author compares the advantages and disadvantages of the two moving types---step by step moving and integrated moving, finally identifies the solutions of how to safely reduce the cycle of the hanging basket.3.There are lots of factors affect the final closure of the prestressed concrete continuous beam bridges, for the extradosed cable-stayed bridge, its girder’s larger integral rigidity demands it overcome larger axial tension in the process of the final closure construction. With two different stiff skeleton installation method, the article analyzes and researches on the two closure ways’effects on the bridge force after the completion of the closure and the release of the temporary lock, and finally identifies a better construction scheme.