Research And Practice On Steel Erection Tube Arch Of Dongchou Bridge

Owing to its unique advantages, concrete-filled steel tube arch bridge has been widely promoted in recent years. However, due to the short history of application, as well as the less experience for reference, the construction, design and research of CFST arch bridge fall behind the need of reality. Based on a practical engineering case, Vietnam Dongchou Bridge, the paper, focused on the key link of the erection of steel arch ribs, studies the construction method of long span CFST arch bridge, with the purpose of solving problems in practical project. The study includes the following four parts.Firstly, a survey on the history, development and status quo of the erection of steel arch ribs was conducted, and the engineering features of different methods were analysed and summarized. The advantages of cantilever crane method lie in the stability of the crane, the flexibility of the application and the convenience of the operation, while its disadvantages lie in the heavy weight of the crane, which will affect the stability of the main structure and increase the stress of the temporary cable tower, resulting in the increase of permanent structural engineering, and the higher closure fee. The strengths of less support lifting method lie in the shorter construction period, better safty, less construction, superior quality and higher accuracy. The superiority of rotating method is the safty and accuracy. Though with heavy rotating structure, the method can take advantage of the geographical environment and the structural features of the bridge and take less time in rotating closure, therefore shorter influence on shipping channel. As for cable erection method, it is extensive in operation scope, powerful in lifting, little in the influence on the channel, clear in technical principles and economical in cost, therefore, it is the most common method used in the erection of steel arch ribs for long span CFST arch bridge.Secondly, combined with the engineering practice and Vietnam situation, different erection methods of steel tube arch ribs were analyzed from the perspective of applicability. It is difficult to apply cantilever crane method in multi-span structure due to technology and high cost. It is suitable for lifting short and heavy steel structure, but not for Dongchou Bridge. Less support lifting method is superior in simple technology, convenient operation, accurate ribs erection and good structural integrity, and may be considered as a scheme for Dongchou Bridge. Rotation method is of difficult technology and needs more space for operation, thus it is not suitable for Dongchou Bridge with limited space. Being of less difficulty in technology with simple construction equipment, cable erection method are widely used in engineering. Its lifting range can cover the whole bridge, with its construction land extending vertically and not being affected by bridge span and framing, therefore, the method is also suitable to Dongchou Bridge. Based on applicability analysis, less support lifting method and cable erection method are chosen as comparative construction methods.Thirdly, a comparative analysis between less support lifting method and cable erection method was conducted in six aspects. Firstly, as to the applicability of the equipment, the floating crane needed in less support lifting method is not easy to obtain in Vietnam, and is of less safty in operation, while the equipment and materials needed in cable erection method is more accessible. Secondly, concerning construction progress, less support lifting method is affected by seasons, resulting in longer construction period; the scheme with cable erection method is not interrupted by seasons, hence, shorter period. Thirdly, about the influence on shipping channel, the construction structure and equipment in water area used in the former scheme occupy the channel the whole construction period, giving rise to great influence on river navigation; the lifting equipment adopted in the latter scheme occupies less channel, hence, less influence. Fourthly, the influence on safty production, with more operations carried out in water area, less support lifting method is of more risk; with less water operations, cable erection method is safer. Fifthly, in term of economy, the construction fee involved in the former scheme is0.15billion Yuan, while the latter0.133billion Yuan. Sixthly, regarding the influence on environment, the operation of the former scheme don’t affect the construction of approach bridge. The latter scheme will affect the construction of approach bridge, but the project duration will not be affected by reasonable organization. In the end, raw support cable erection method was chosen as the installment scheme for Dongchou Bridge.Fourthly, the cable erection scheme for the Dongchou Bridge was arranged, meeting the lifting requirement of main bridge and reducing the influence on the construction of approach bridge. The lifting segment of arch rib was rationally divided and the calculation load of construction determined. A finite element software of MIDAS was adopted in the design and checking calculation of the main lifting structures, ensuring that the members stress, rigidity and stability of the tower structure adopted meet the specification and construction requirements.