Analysis Of Mechanical Perfomance On Cable Tower And Buckle Tower System Of A Big Span Steel Box Arched Bridge During Construction

XJ Bridge is a half-through steel box tied arch double-track railway bridge with the biggest span in and abroad China. The spans are arranged as (40.2+52+382+52+48.15) m. Due to the limit by the site conditions, the methed of integrated installation of cable tower and buckle tower is used in the rib hoisting and splicing. The buckle tower of XJ Bridge is145.86m high, the cable tower is24.2m high and the biggest hoisting tonnage of arch rib is237t, which are all in the forefront of domestic and foreign construction projects. The key construction techniques of integrated installation of cable tower and buckle tower of XJ Bridge are studied and also the mechanical behavior of the cable and fixing tower during the construction process is analysed. The main work and conclusions are as follows:1. Key construction techniques of integrated installation of cable tower and buckle tower are studied and summarized. The key point is to control tower’s top horizontal displacement, so as to lessen the bending moment of cable tower and buckle tower. So the horizontal force caused by the arch rib’s hoisting and fixing cable’s tensioning must be reduced.2. The simulation method of cable and fixing tower during the integrated installation of cable tower and buckle tower is studied. The bottom of cable tower and top of buckle tower were connected by pin roll. Therefore, the analyses of cable tower and buckle tower could be done respectively, the connection between them can be simulated as a hinge joint. The top of fixing tower was considered to be the support of cable tower’s hinge while analyzing the cable tower, and the counteracting force of cable tower was applied to the top of buckle tower as a external load during the buckle tower analysis.3. Calculated and analysed the mechanical behavior of cable tower during the whole construction process of XJ Bridge’s arch rib. Results shows:The strength and stiffness of the cable tower meets the requirements under the joint action of the dead weight、wind load and the most unfavorable construction load. The cable tower’s maximum stress is 183MPa, and tower’s maximum top horizontal displacement is14mm.4. The mechanical behaviors of buckle tower during the arch rib construction of XJ Bridge are analysed. Results show that the strength and stiffness of the buckle tower meets the requirements under the combined action of the dead weight、wind load and the most unfavorable construction load. The buckle tower’s maximum stress is120MPa and tower’s maximum top horizontal displacement is10mm.5. The stability of buckle tower during the arch rib construction of XJ Bridge is analysed. Results show that under the combined action of dead weight、wind load and the most unfavorable construction load, the minimum stability coefficient of buckle tower is7.62, the buckle tower’s stability meets the requirements.The results of this paper offered basis for rib hoisting and splicing of XJ Bridge during the integrated installation of cable tower and buckle tower.