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  • 连接:设计悬吊桥

    Unlike other bridges, a suspension bridge actually suspends or hangs the road using huge cables. The cables are wrapped over large towers, and connect to anchors at either end of the bridge. This delicate balance of strength and precision is not easy to achieve, and, in fact, architects and structural engineers use parabolas to help construct these bridges.
    ::与其他桥梁不同,悬浮桥实际上会用巨大的电缆挂起或挂起道路。 电缆被大塔包住,并在桥的两端连接到锚上。 这种微妙的实力和精度平衡不容易实现,事实上,建筑师和结构工程师使用抛光灯帮助建造这些桥梁。

    lesson content

    Look at the distinctive shape of the suspension cables. Their parabolic shape helps ensure that the bridge stays up and that the cables can sustain the weight of hundreds of cars and trucks each hour. Both gravity and compression/tension forces create the curve seen in the cables of suspension bridges. The parabolic cables effectively distribute the weight of the bridge and transfer the compression forces to the towers to which the cables are attached 1,2 .
    ::看看悬浮电缆的独特形状。 抛物线的形状有助于确保桥梁保持畅通,电缆能够保持每小时数百辆汽车和卡车的重量。 重力和压缩/压压力都创造了悬浮桥电缆所见的曲线。 抛物线的电缆有效地分配了桥梁的重量,并将压缩力转移到电缆连接的塔, 1,2。

    1. The towers of the Golden Gate Bridge are 500 feet high above the roadbed, and they are 4,200 feet apart. If the cable is 8 feet above the roadbed at its lowest point, describe the vertex of the parabola formed by the cables as a point on the y -axis.
    ::1. 金门大桥的塔楼在路床上方500英尺,相距4 200英尺,如果电缆在最低点路床上方8英尺,则将电缆形成的抛物线的顶部描述为Y轴上的点。

    2. Find the equation of the quadratic function by using the three points you know and solving a system of three linear equations.
    ::2. 通过使用你所知道的三点和解决由三个线性方程组成的系统,找到二次函数的方程。

    3. Graph the quadratic function.
    ::3. 绘制二次函数图。

    4. The Verrazano Narrows Bridge in New York City is the longest suspension bridge in the Western Hemisphere. The towers are approximately 4,260 feet apart and 465 feet above the roadbed. (The bridge is so long that the curvature of the Earth had to be taken into account, so the towers are not parallel; they are off by 1 5 8   inches.) The lowest point of the cables is 4 feet above the roadbed 3 . Repeat problems 1-3 above for the Verrazano Narrows Bridge.
    ::4. 纽约市的Verrazano Narrows桥是西半球最长的悬浮桥,其塔面相隔约4 260英尺,路床上465英尺。 (这座桥很长,必须考虑到地球的弯曲,因此塔面不平行,关闭了158英寸。 )电线的最低点是路床以上4英尺。 3 Verrazano Narrows桥上面重复上面的问题1-3。

    5. Compare the cables of the two bridges. From their graphs, what conclusions can you draw? Explain.
    ::5. 比较两座桥梁的电缆:从两座桥梁的图表中,你能得出什么结论?解释。

    This video by Curiosity Machine discusses engineering concepts behind building suspension bridges. 
    ::这段影片由Curiosity Mechanic制作, 讨论建筑悬架桥背后的工程概念。

     

     

    References
    ::参考参考资料

    1. "Suspension Bridge," last edited May 23, 2017,
    ::2017年5月23日 上次编辑的"暂停桥"

    2. "Golden Gate Bridge," last accessed May 26, 2017,
    ::2. “金门桥”, 2017年5月26日最后一次访问,

    3. "Verrazano Narrows Bridge (Staten Island/Bay Ridge, 1964) | Structurae," last accessed May 26, 2017,
    ::3. "Verrazano narrows桥(Staten Island/Bay Ridge,1964年) Struitrae," 2017年5月26日最后一次访问,