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问题 单项选择题

某钢筋混凝土挑梁(b×hb=240mm×300mm)，埋置于丁字形截面的墙体中，如题图；挑梁下墙体厚均为240mm，采用MU10砖、M2.5砂浆砌筑。

楼板传给挑梁的荷载有：梁端集中作用的恒载Fk=4.5kN，作用在挑梁挑出部分的恒载g1k=10kN/m，活载q1k=1.8kN/m，楼板压在挑梁埋在墙内部分的恒载为g2k=10kN/m，顶层屋面板传给挑梁荷载，g3k=15.5kN/m，q3k=1.8kN/m，墙体自重19kN/m3，挑梁挑出部分自重1.35kN/m，挑梁埋在墙内部分自重1.8kN/m。

顶层的倾覆力矩与（）项数值最为接近。

A．28.75kN·m

B．18.4kN·m

C．38.25kN·m

D．22.7kN·m

答案

参考答案：A

解析：

求xo挑梁埋在墙体的长度ι1分别为3.0m和1.8m，均大于2.2hb=2.2×0.3=0.66m，根据规范7.4.2条的规定，挑梁计算倾覆点到墙外边缘的距离xo=0.3hb≯0.13ι1，即xo=0.3×0.3=0.09m＜0.13ι1=0.13×1.8=0.234m。

挑梁的自重和承担的恒载的合力为15.5+1.35=16.85kN/m。

挑梁所承担的活载为1.8 kN/m，恒载起控制作用。

根据《建筑结构荷载规范》第3.2.5条第=款的规定，恒载的分项系数为1.35，根据《砌体结构规范》第4.1.6条(4.1.6)的规定，在验算倾覆时，这时的分项系数取1.2

单项选择题

钢筋混凝土用冷轧带肋钢筋，每批数量不大于( )t的，取一组试样进行钢筋试验。

A．30

B．50

C．60

D．100
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填空题

Recycling Paper


The process of recycling paper can help to reduce deforestation and energy consumption on a significant scale. There are many different reasons why we should recycle paper products, and some of these are (26) in the paragraphs below.
Energy consumption will always be on the (27) as population levels grow, and so any manufacturing processes which help to reduce energy consumption are (28)
The Energy Information Administration (EIA) claim that there can be as (29) as a 40% energy saving when recycling paper over producing paper (30) the direct raw material.
Although recycling paper has many (31) , it also has its drawbacks. One of these drawbacks is that we cannot recycle the (32) paper product for eternity, as the fibers contained within the paper degrade over time, (33) their strength and length.
On (34) , an individual paper fiber can only be recycled a (35) of six times. Although this is a significant drawback, the six time recycling process will help to (36) a great deal of energy when you consider (37) much paper there is to be recycled.
If paper fibers can be recycled up to 6 times, and we recycled all paper products, this could help to (38) the intensity of deforestation for paper products up to a factor of 6.
With paper production said to (39) around 40% of harvested wood, and paper said to (40) around 90% wood, you can see how recycling paper is an important process for the (41) of our forests.
Today, the use of recycled paper products is on the increase, as more and more people begin to recycle paper (42) products around the home.
Although there are slight differences in the recycling processes of different (43) of paper products (e.g. corrugated, mixed paper, newspaper products), we are able to recycle just about any type of paper product around today.
The recycling logo helps to (44) a recyclable product and can also sometimes help to identify if the product contains any recycled material, in the form of a percentage. This helps a consumer to identify the (45) of recycling various products.

A. maximum B. deal C. number D. scale
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