问题 单项选择题

抗震等级为二级的钢筋混凝土框架结构,其节点核心区的尺寸及配筋如图所示。混凝土强度等级为C40(fc=19.1N/mm2),主筋、箍筋分别采用HRB400(fy=360N/mm2)和HPB300(fyv=270N/mm2),箍筋混凝土保护层厚度20mm。已知柱的剪跨比大于2。试问,节点核心区箍筋的配置,为下列何项时,才能最接近又满足规程中的最低构造要求().

A.

B.

C.

D.

答案

参考答案:D

解析:

解答如下:

根据《高层建筑混凝土结构技术规程》6.4.10条第2款:

抗震二级,λv=0.1,ρv≥0.5%

ρv≥λvfc/fyv=0.1×19.1/270=0.71%>0.5%

配箍率,假定箍筋直径为8mm:

即: Asv1/s≥0.520

,s≤97mm,原假是正确,故应选

框架节点核心区水平箍筋的配箍率应满足《高层建筑混凝土结构技术规程》6.4.10条规定,应注意的是,柱剪跨比λ<2的情况。

阅读理解

We are all busy taking about and using the Internet. But how many of us know the history of the Internet?

Many people are surprised when they find that the Internet was set up in the 1960s. At that time, computers were large and expensive. Computer networks didn’t work well. If one computer in the network broke down, then the whole network stopped. So a new network system had to be set up. It should be good enough to be used by many different computers. If part of the network was not working, information could be sent through another part. In this way, computer network system would keep on working all the time.

At first the Internet was only used by the government (政府). But in the early 1970s, universities, hospitals and banks were allowed to use it, too. However, computers were still very expensive and the Internet was difficult to use. By the start of the 1990s, computers became cheaper and easier to use. Scientists had also developed software that made “surfing” the Internet more convenient.

Today it is easy to get on-line and it is said millions of people use the Internet every day. Sending e-mails is more and more popular among students.

The Internet has now become one of the most important parts of people’s life.

小题1:The Internet has a history of more than _________ years.

A.fifty

B.ten

C.forty

D.twenty小题2:A new network system was set up to_______.

A.make computers cheaper

B.make itself keep on working all the time

C.break down the whole networks

D.make computers large and expensive小题3: At first the Internet was only used by __________.

A.the government

B.universities

C.hospital and banks

D.schools小题4: ________ made “surfing” the Internet more convenient.

A.Computers

B.Scientists

C.Software

D.Information小题5: Which of the following sentences is true?

A.In the 1960s, computer networks worked well

B.In the early 1970s, the Internet was easy to use.

C.Sending e-mails is more popular among students than before.

D.Today it is still not easy to get on-line.

单项选择题