Yangtze River Daily: built in the earthquake zone can resist eight earthquake
The day before yesterday, the closure by the headquarters in the Han Dynasty in the two bureau of aviation construction of the Xigu District of Lanzhou the Yellow River bridge. This is the northwest region in the Yellow River, the largest and the highest tower of cable-stayed bridge, the more concern is that the bridge is in the northwest earthquake zone, the earthquake resistance of eight earthquake.
Lanzhou is the ancient Silk Road City, west the Yellow River bridge is Lanzhou south highway around key control projects, across the Yellow River, Lan Xin railway and national highway 109, crossing the two national water conservation area. Bridge a total length of 1003 meters, of which the main bridge is 714 meters long, the design for the composite girder cable-stayed bridge with three span steel Twin Towers, main span 360 meters, the project contract amount of 490 million yuan.
The bridge where regional hydrogeology is bad, the flow velocity difference is large, the Yellow River, river pebbles accumulation, and is one of China's major earthquake zone - Lanzhou Tianshui earthquake zone, which brings great difficulties to the design and construction of the bridge.
The post two air Bureau of Lanzhou Xigu the Yellow River Bridge Project Manager Wang Jinjun said: "this bridge from design to construction, many aspects of the unique innovation. Steel Zhanqiao bridge in the country for the first time the bench pile and steel anchor pile combining form, a good solution to the problem of flow velocity and hydrogeological main river cobble layer; at the same time, the bridge is designed as a strong earthquake, eight earthquake resistant."
Data show that the Lanzhou tin tin earthquake zone is the largest one in China, but also the most powerful earthquake areas. The post two air bureau project chief engineer Hu Yongbo introduction, the bridge is located in high seismic zone, therefore, the bridge for earthquake resistance and isolation requirements higher than the general bridge. Based on the seismic analysis, the viscous dampers are installed in the middle and side of each main tower of the bridge. The whole bridge is set up to 4, which is the biggest damper used in the whole country. Compared with the domestic non seismic belt on the bridge to install a large number of dampers, the amount of steel bridge reinforcement is also more.
The viscous damper is equivalent to the "safety air bag" on the bridge ". "Once an earthquake occurs, the damper can reduce the impact force of 650 tons to the maximum extent, and effectively reduce the displacement of the key parts of the bridge structure." Hu Yongbo said that even if the earthquake at the same level of the Wenchuan earthquake, the bridge structure will not be damaged.
In view of the characteristics of the high bridge deck and the the Yellow River River Valley, the construction team of the two air Bureau has carried on the wind tunnel test for many times to ensure the safety of construction and the quality of the bridge. Through independent research and development of bridge crane beam in walking, the air fight bridge, the main bridge closure 2 months ahead of schedule.
Published in the "Yangtze River Daily" in September 23rd 12 Edition
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