• 靈活伸縮的橋——應對地震的新技術

    案例來源:
    http://inhabitat.com
    案例標簽:
    所在國家:
    美國 
    用途:
    • 其他
    結構:

    案例詳情:

    【介紹】


    靈活伸縮的橋——應對地震的新技術


    西雅圖是美國太平洋西北區最大的城市,這里依山傍水,氣候溫和,是絕佳的度假勝地和宜居城市。這里雖然不在全球地震帶上,但處在一條地質斷層帶上,再加上城市人口密度大,樓房集中,一旦發生地震,人員與財產損失都是不可估量的。西雅圖市政府提出方案,要沿著城市海岸線建一座大橋。建成后即成為安全通道,一旦地震發生,大橋就是一條寬敞的救生通道。工程預計明年春天完工,這也將是世界上首座抗震大橋。


    建設新大橋之前,西雅圖市就一直對阿拉斯加高架橋的存在爭論不止。截止到目前,討論的最終結果就是重新用隧道代替高架橋,并且隧道的斜坡入口處一律使用抗震性技術。其中的“記憶性鋼管”和具有彎曲延展性混凝土具有一種無與倫比的“魔力”——在每一次持續性大震小震后都能自我恢復。


    大橋是對新一代建造技術的全新利用,世界范圍內尚屬首次。自然的破壞力確實無法避免和精確預算,在這種先天不利的情況下,技術人員就先進行試驗性測試,用橋入口做試驗。試驗15年的結果就是利用這種新技術,橋能承受7.5震級的壓力,并順利恢復。


    入口指示司機直接從北向的99號公路進入南部市中心迪爾伯恩。因為之前橋入口的位置正好處在市體育場,一旦發生地震,損失較大,所以在新的大橋開工后,入口的位置也會有所改變。


    【原文】


    World’s first “flexible bridge” in Seattle keeps its shape after a big earthquake


    Although Seattle is not a city plagued by earthquakes, its position on the waterfront of the Pacific Northwest makes it vulnerable to a big quake, especially given its population. City planners taking this into consideration are building a new ‘flexible’ bridge along the city’s shoreline that could help keep key roadways open for traffic in the event of a major quake. When it opens next spring, the bridge could be the first earthquake-proof roadway of its kind in the entire world.


    The fate of the Alaskan Way Viaduct has been a topic of many a heated debate in Seattle for years. Currently, a project is underway to replace part of the aging elevated road with a tunnel. The above-ground portion of the road, though, will be comprised of an exit ramp that utilizes new technology to protect it from collapsing during even a very strong earthquake. Memory-retaining metal rods (called “Shape Memory Alloy” rebar) and a bendable concrete composite will help the bridge sustain quakes and then return to its original shape, according to the Washington State Department of Transportation.


    The department says this bridge will be the first in the world to employ the new building technology. While it’s impossible to guarantee that any man-made structure can be earthquake-proof, especially since the magnitude of Seattle’s next big earthquake is unpredictable, builders are aiming for the next best thing: a flexible bridge that can absorb earthquake forces, rather than be destroyed by them. Seattle’s new flexible exit ramp bridge will be the first real-world application of materials that the Earthquake Engineering Lab at the University of Nevada, Reno has been researching for 15 years. In testing, bridge columns using the new building technology have withstood magnitude 7.5 earthquakes and then returned to their original shape.


    The exit under construction will guide drivers from northbound State Route 99 onto South Dearborn Street, which leads into the heart of the downtown district. The ramp sits immediately west of the city’s sports stadiums, a spot seismologists have predicted would be particularly vulnerable in the event of a large earthquake. Construction on the flexible bridge began in September 2016 and the new exit ramp is expected to be open next spring.

     

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