本文对三跨预应力连续箱梁桥的边跨与中跨比例问题进行了初步的探讨。

The paper discussed proportion between side span and middle span in three spans prestressed continuous box beam bridge.

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箱形伸缩臂作为汽车起重机的主要受力构件，其重量一般占整机的13 ~ 20%，而大型起重机占的比例则更大。

As the main stress component, box truck crane telescopic boom usually accounts for the weight machine for 13 ~ 20%, while the percentage of large cranes is greater.

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