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發表於 2013-10-12 05:08:11
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回復 小紀 #1 的帖子
Suspension bridge usually only has two piers had two main reasons. First, it is very expensive to built the pier. To save cost it is better to only use two piers. The second reason is to simplify the analysis of the structure. When there are more spans (more piers), the dynamic load from one span will transfer to other span. if a suspension bridge has more span, the deck of the bridge may move so much that it is un-usable.
Regarding your second questions, it is more sensible to have a higher pier for longer span because of the loading of the cable. If the cable angle is too shallow (low pier with long span), the load in the cable will increase a lot. For example, for 45 degreed angle, the load in cable is about 1.41 times the loads its carry; for a 30 degreed angle, the load in cable is about 2 times the load it carry; for 15 degreed angle the load in cable is about 3.86 times the load it carry. |
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樓主: 小紀
在線雷達
發表於 2013-9-15 23:56:21
