| Rotation construction, a new construction technique that has always been popular in the mountain areas, are beginning to entering the cities because of the appearance of concrete-filled steel tubes and new forms of bridge constructor in recent years. Together with the monumental developments of our railways, a great quantity of PDLs and high-speed lines has entered into construction and action, whereas flyover railway bridges have increased in number. Due to the often busy flow of traffic on the lines beneath those bridges, the technique of rotation construction, which dose not interferer with the traffic flow, are now widely accepted. Still, there are many key problems concerning this technique that had not been solved well, like the difficulty in determing the reasonable cable power or the easy loss of constructor equilibrium during the rotating stage. Those problems should be analyzed for the future development of rotation construction.This paper has chosen as background the process of the rotation construction of an iron-steel bowstring arch bridge on the Beijing-Shanghai High-speed Railway over the Beijing-Kaifeng Highway. It has analyzed the construction process using the Midas/civil finite element software. This paper has allayed the deflection stress of the rotation construction during the construction stage; and has done relatives researches on the influences of different stages of construction on the cable and boom power, and those of the changes in the weights, cable power and the inner power of brackets on the deflection of rotation constructor. At the same time, with the in-the-field surveillance data in the rotating process of the construction, it has summed up the influence of different stages of construction on the unbalanced moment and the shifting of the weight center. It has come to the conclusions as follow:1. The analysis of the constructor as a whole shows that the steel-box type of cross section has in nature enough force to counter the stretching force of the cable and the boom. The stress of cross section reaches its maximum value of 44Mpa ashen the rotation construction has completely come off the brackets. The demands of stability and strench can be met perfectly;2. During the removing process of brackets and stretch-draw booms, the influence on the stretching power of the cables is very small. In fact, during the entire construction process, the general influence on the cable power is within 3.4%, with the main change of cable power occurring during the construction stage of the stretch-draw cables;3. During the different constructing stages of the removing process of brackets, the change of the inner power of booms is small. However, during the process of stretching the cables for the second time, the inner forces of suspender 3,4 and 5 have changed greatly, suspender 5 has increased from 35kN to 407kN, with the axial stress power of 36Mpa;4. The deflection of rotation construction is caused by the stretching's of the cables. The first time, only the main arch rib bent slightly upward, as the second time, the whole construction moved upward due to the suspenders connecting the arch rive and the main longitudinal girder;5. Applying weights at the sidespin will also affect deflection. However this only means with the spinning of the rigid body, the midspan increases as the sidespin decreases accordingly. The distance between the weights applied at the sidespin and the arch springing also affect the deflection amount. The amount of deflection changes in propulsion with the weights applied;6. In the stages of removing the brackets and rotating, the weight center and the unbalanced moment of the rotation construction change continually, inconsequence, so does the inner force of the arch springing.
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