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问题 单项选择题

73～76 已知一预制空心板梁的截面尺寸如题73～76图所示，计算跨径L=12.6m，承受计算剪力：支点=236.7kN，跨中=43.7kN，其间按直线变化，采用C30号混凝土，HRB335钢筋7作为受拉钢筋(Ag=22cm2)，ag=3.6cm。仅用HRB335钢筋10配置箍筋。

经验算需配抗剪钢筋，假定距支点h/2处的计算剪力为229.5kN，最大剪应力发生处的腹板宽度b为25cm，计算得箍筋配筋率（%）为（）。

A．0.24

B．0.19

C．0.13

D．0.54

答案

参考答案：B

解析：

因仅设置箍筋，主梁配筋率：

由《规范》公式(5.2.7-2)得

单项选择题

学生的知识学习过程主要是一个对知识的内在加工过程。它包括三个阶段，即知识获得、知识保持和（）

A.知识巩固

B.知识运用

C.知识提取

D.知识迁移
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单项选择题

Since 1960, the fast-growing town of Hotstone, Arizona, has drawn water from the Gray River, which feeds Lake Mudfish. If the town’s water use continues to grow at its present rate, in about 20 years the water level of Lake Mudfish will inevitably decrease to the point that it can no longer support its biologically fragile population offish.
The prediction above is based on which of the following assumptions ？（）

A. As the town’s water requirements grow, it will not be able to meet those requirements by drawing on water sources other than the Gray River.

B. Since 1960, the lake’s population of fish has become more biologically fragile.

C. The amount of water that the lake loses to evaporation each year will increase over the next two decades.

D. There are multiple sources of water besides the Gray River that feed into Lake Mudfish.

E. The town of Hotstone will be able to reverse its trend of increasing water use if it implements an aggressive water conservation program.
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