In the early morning of July 30, 2019, after a thrilling 90-minute “flyover” in the air, an ultra-long twisting double-wing cable-stayed bridge weighing more than 80,000 tons was realized across the Beijing-Guangzhou Railway Bridge on Lekai Street, Baoding City, Hebei Province. The perfect turning and closing in the air broke the world record of weight, span, and hinge diameter in the history of bridge construction in the world.
The sub-tower rotating bridge is 204 meters long and weighs 35,000 tons. The pivoting bridge of the mother tower is 263.6 meters long and weighs 46,000 tons. It takes about 70 minutes to complete the pivot.
Let us recall this shocking scene again.How does such a heavy bridge rotate?
According to CCTV.com, in order to make this behemoth rotate, "black technology" was used during the construction of the bridge-a "rotating device" with a diameter of 6.5 meters and a weight of 92 tons was installed under the bridge base. , It is through this "super bearing" that the entire bridge of tens of thousands of tons is rotated.
The working principle of bridge swivel construction is like the free rotation of the excavator's shovel arm. A rotating axis is prefabricated on the abutment (single-hole bridge) or pier (multi-hole bridge), and the bridge is divided into The upper part and the lower part are integrally rotated, and the lower part is a fixed pier and foundation. According to the actual situation of the site, the upper structure can be prefabricated on the embankment or the river bank, and the rotation angle can also be freely rotated according to the terrain.
The swivel spherical hinge is composed of upper spherical hinge, slideway, lower spherical hinge, pin shaft and other components. The spherical hinge is the core of the rotating system and the key structure of the rotating construction. A slight mismatch in the size of the upper and lower ball hinges will cause the ball hinges to be completely stuck and unable to rotate. Its production and installation accuracy requirements are extremely high.
The production of spherical hinges is very strict.
On the contact surface of the ball joint, the roughness is controlled to the micron level, and no obvious machining tool marks are allowed. In addition to machining errors, the material of the ball hinge is also very important, and it must have both compression resistance, friction resistance and a very low coefficient of friction.
The spherical hinge adopts high-performance non-metallic composite materials and high-precision spherical processing technology, which can not only significantly reduce the friction coefficient, but also meet the design requirements of large bearing capacity, which solves the problem of super large bearing capacity and flexible rotation of the large tonnage bridge swivel device.
More than ten years ago, the steel/concrete hinge commonly used in Chinese engineering has a coefficient of friction of up to 0.3 due to the material characteristics, and a huge tonnage winch must be used to rotate it. Now the swivel spherical hinge has formed a series, which can adapt to various working conditions such as different bearing capacity requirements, pier bottom and pier top.
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