问题 单项选择题

某高度为50m的高层剪力墙结构,抗震等级为二级,其中一底部墙肢的截面尺寸如题图所示:混凝土强度等级为C30,剪力墙采用对称配筋,纵向钢筋为 HRB335钢,竖向和水平分布钢筋为HPB235钢。as= =25mm。

考虑地震作用组合时,墙肢的剪力设计值Vw=2600kN,轴向压力设计值N=3375kN,计算截面处剪跨比λ=1.5。假定剪力墙水平钢筋间距s=200mm,试问剪力墙水平钢筋的面积Ash(单位:mm2)与()项数值最为接近。

A.341

B.290

C.142

D.196

答案

参考答案:A

解析:

(1)

(2)Vw=1.4V=2600(kN)

(3)验算剪压比:

查表4.7.2,γRE=0.85,

(4)

代入得:

所以Ash=341mm2

单项选择题
单项选择题

While the ripples of America’s subprime-mortgage crisis have spread far and wide, Latin America—a place long associated with financial disaster—has remained improbably calm. Banks have reported no unpleasant surprises. Brazil and Peru have been blessed with coveted investment-grade ratings. Surprisingly, perhaps the fleetest country of all has been Argentina. Since it emerged from the financial crisis of 2001-02, it has been one of the world’s fastest-growing economies. It is expected to expand faster than most of its neighbors again this year.

Quite simply, it barely has any credit. Back when its economy virtually collapsed, the country suffered a run on its banks, followed by a freeze on withdrawals, and a massive currency devaluation. As a result, bank lending to the private sector shrivelled, from 23.8% of GDP in 2000 to 10.8% in 2003. Since then, it has rebounded to a piddling 13% ; by contrast, the ratio in Brazil was 36.5% in 2006. Almost all of these loans in Argentina are accessible only on a short-term basis.

Once its recovery began in June 2002, Argentina became a paradise for business. Unemployment of over 20% kept wages down, and the devaluation gave exporters an edge on foreign competitors. The ample productive capacity left idle by the crisis meant firms could expand without making big investments. And the windfall profits reaped by agricultural exporters, thanks to record commodities prices, enabled many of them to finance new projects out of earnings. Hence the economy could grow at almost 9% a year with little need for credit.

But such a lucky confluence of factors could not last. Starting in early 2005 ,.inflation picked up, a sign that the installed capacity was starting to limit output. Salaries and prices for raw materials increased sharply, cutting into profits. And farmers were particularly hard hit when the government nearly doubled the taxes in farm exports. Now, just as companies need to embark on big investments if they are to keep growing, their margins are no longer big enough to pay for the expansion and they need to borrow.

So, the time is ripe for the country’s financial system to recover. But a number of things are in the way. Foremost is Argentina’s business risk. Those in the informal economy (which represents over 40% of GDP) can neither save nor borrow legally, lest they become known to the taxmen. The rest remain cowed by memories of the crisis. Although Argentines have poured their savings into property, fuelling a construction boom, they still hold about four-fifths of their deposits abroad.

Inflation, fuelled by a public-spending binge, state-mandated wage increases, and a cheap currency, is not helping either. No one knows how high it is. The consumer-price index is doctored to keep the official rate below 10%, but private estimates suggest it is near 25%. Without a reliable index of inflation, lending is almost impossible, even for the medium term. And the central bank has kept interest rates ply negative in real terms, encouraging workers to spend their wages rather than to save.

Argentina’s economy began its recovery in 2002. According to the text, which of the following is not the reason()

A. Low wages

B. Low unemployment

C. Low value of currency

D. Low commodities prices of exports