首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
The Fall of WorId Trade Centre I. Flashback of the disaster A. The twin towers of the World Trade Center collapsed B. A rela
The Fall of WorId Trade Centre I. Flashback of the disaster A. The twin towers of the World Trade Center collapsed B. A rela
admin
2022-01-23
25
问题
The Fall of WorId Trade Centre
I. Flashback of the disaster
A. The twin towers of the World Trade Center collapsed
B. A relative success in terms of【T1】___________
- the buildings performed "magnificently"
- the towers stayed standing for about【T2】______each
II. An extraordinary design
A.【T3】______skyscrapers
-【T4】_________throughout a building
- diagonal beams as their means of support
B. twin towers
- designed and built with special attention to【T5】________
-【T6】______hurricane-force winds of up to 200 mph
- sway up to several feet【T7】___________
- the secret of its build-up:【T8】__________
- supporting steel column
- majority of the beams framed the outside walls—a solid "【T9】______" design
- smaller group of steel beams shot【T10】____of the buildings and bore【T11】________of supporting the towers
III. The fundamental cause of its collapse:【T12】______
A. the high temperature failed【T13】________and weakened the insulation around the steel
B. the heat【T14】_____________
C. top-floor fell and hence the demolition IV. Collapse: a controlled demolition, like a【T15】____________
【T12】
The Fall of World Trade Centre
Well, my topic today is Architecture, and to be specific, what I am going to talk about is World Trade Centre — the skyscrapers.
After watching the twin towers of the World Trade Center collapse, twice reducing 110 stories to five in less than a minute, it’s hard to see how the buildings could have ever been considered safe. It’s even harder to see how engineers can look at the events of September 11, 2001, as a relative success in terms of architectural strength. Consider this: the rubble at the site weighed a million tons. The site spanned a vast 16 acres. The nonstop cleanup, conducted day and night, still took the better part of a year. Even if the greatest loss — so many human lives — is excluded, there’s no arguing: this was, in all senses, an enormous disaster.
And yet, for all the destruction — and for all the disbelief. Americans felt as they watched the towers collapse — engineers unanimously say that the buildings performed "magnificently" after terrorists crashed a plane into the side of each. Because the towers stayed standing for about an hour each, they gave rescue workers enough time to get tens of thousands of people out. The towers owed their resilience largely to their architect, Minoru Yamasaki and structural engineer Leslie Robertson. The men’s original design enabled the buildings to withstand the impact of the planes, only after jet-fuel fires weakened their steel beams.
Constructed with cheaper methods, many other buildings would have collapsed immediately. Today’s most common skyscraper design places vertical support beams throughout a building. Others have diagonal beams as their means of support. But the World Trade Center was built before those were the standards. Raised in the 1960’s, the glass-and-steel towers were designed and built with innovation and special attention to safety and stability because of their extreme height. Engineers wanted to make sure the towers could withstand hurricane-force winds of up to 200 mph — on an especially windy day, the towers could sway up to several feet in either direction. With memories of a 1945 plane crash into the Empire State Building lurking in their minds, engineers and architects also designed the towers to withstand the force of a Boeing 707.
There are several reasons to make the tower magnificent. Firstly, the engineers agreed that the secret to ensuring the buildings would stand tall under extreme circumstances rested in their supporting steel columns, which were set up differently from most skyscrapers’. Secondly, the majority of the beams framed the outside walls of the towers: 61 beams per 211-foot side provided maximum reinforcement. Engineers often refer to this as a solid "steel tube" design, and rightly so compared to most buildings, which may have vertical support columns spaced as far as 20 feet apart. Thirdly, the outer columns helped the buildings withstand a huge wind load, but another smaller group of steel beams shot through the centers of the buildings and bore the main load of supporting the towers. This "core", which housed elevator shafts and stairwells, was connected to the outer steel columns by still more steel running through each concrete floor. The "double support" may have been what ultimately kept the buildings standing for so long.
What actually caused the twin towers to fall? All the same, no amount of reinforcement could have prevented the towers’ eventual collapse. Immediately after September 11, most engineers thought the fires, and not the planes’ impacts, were to blame. That theory has generally held up. A federal investigation was inconclusive, but it did conform with engineers’ suspicions. The steel columns didn’t actually melt. But as the fires inside the buildings consumed more and more jet fuel — about 24,000 gallons of it — they overwhelmed the buildings’ sprinkler systems, started to weaken the concrete insulation around the steel, and then deliberated the steel itself. Most of the fluffy fireproofing material on the towers’ steel columns was blasted off by the plane crashes. With flames reaching temperatures of 1,500 degrees Fahrenheit and higher, the steel columns started to warp, and the top floors buckled. From then on, the towers had no more chance of standing than a building targeted for demolition. Their collapse was the first known instance of steel buildings collapsing because of fire alone.
In fact, the collapse played out just like a controlled demolition. To destroy a building, experts usually place explosives not just on the lowest three floors, but also on higher floors. With the top floors exploding, demolition experts can create what they call a "pancake effect", which you might realize is the same as a downward domino-effect. Unlike dominos, of course, the towers fell straight down rather than sideways. But their downfall was caused by the same forces that knock a line of dominos on their faces: Floors on the top gave in, crashing through the floors below them. As each concrete floor fell, it added force to the collapse — making it harder for each floor to hold up against the increasing pressure. Once the top floors gave way, the rest of the catastrophe was inevitable.
To be exact, many lives lost, but many saved. If the towers were never going to stay standing, why all the extra support? Was it futile after all? Suppose for a minute that the towers hadn’t been built with all that reinforcement — that they’d collapsed a few minutes after being struck. The rubble at the side still would weigh a million tons. The site still would have taken as long. But how many more people would have died? It’s a figure no one wants to calculate. Thankfully, because a team of engineers and architects made the Trade Center as safe as it could possibly be.
To sum up, I first recalled the disastrous episode of the fall of the World Trade Centre, then I explained how extraordinary the design is. After that, I summarized the reasons of its catastrophic collapse. That’s it for today.
选项
答案
fires
解析
归总题。讲座里提到: Immediately after September , most engineers thought the fires, and not the planes’ impacts, were to blame.从这句话可以归纳出真正的罪魁祸首是火。
转载请注明原文地址:https://kaotiyun.com/show/B7IK777K
0
专业英语八级
相关试题推荐
HowtoConquerPublicSpeakingFearI.IntroductionA.Publicspeaking—acommonsourceofstressforeveryoneB.Thetruthabou
(1)Thishasbeenquiteaweekforliterarycoups.Inanalmostentirelyunexpectedmove,theSwedishAcademyhavethislunchtime
Properarrangementofclassroomspaceisimportanttoencouraginginteraction.Today’scorporationshirehumanengineeringspec
DifferentTypesofLearningI.ThedefinitionoflearningA.AprocessofpeopleexperiencingrelationshipbetweeneventsB.【T1】
DifferentTypesofLearningI.ThedefinitionoflearningA.AprocessofpeopleexperiencingrelationshipbetweeneventsB.【T1】
DifferentTypesofLearningI.ThedefinitionoflearningA.AprocessofpeopleexperiencingrelationshipbetweeneventsB.【T1】
A、Thegolfcourse.B、Theoutdoorsports.C、Theoutdoorenvironment.D、Thelandscape.C第二部分的对话一开始男士就说到他想要一些新鲜空气和绿色植物,接着提到了高尔夫球场以及
Psychologistshavemanytheoriestoexplainhowwerememberinformation.Themostinfluentialtheoryisthatmemoryworksasak
Now,thesecondcharacteristicofactivelearnersistoreflectoninformationand【T1】______.Beingreflectiveisanimportantp
A、Objective.B、Pessimistic.C、Skeptical.D、Subjective.C观点态度题。对话一开始女士就表示,她对人类破坏地球这一观点并不是十分赞同。接下来她又说,不能因为短短二十年的环境异常就要求人类改变自己的生活方式
随机试题
急性肾衰竭少尿期患者需要紧急处理的电解质紊乱是
估价作业方案的核心是解决将要做什么、什么时候做、由谁去做以及如何做,即是关于未来一系列行动的方案。具体来说,估价作业方案的内容主要包括:()。
资本公积的内容不包括()。
支票的提示付款期限为自出票日起1个月。()
C企业在生产经营淡季,需占用1250万元的流动资产和1875万元的固定资产;在生产经营高峰期,会额外增加650万元的季节性存货需求。企业目前有两种营运资本筹资方案。方案1:权益资本、长期债务和自发性负债始终保持在3400万元,其余靠短期借款提供资金来源。
学生学习的内容有()。
余某犯罪后自动到公安机关投案,并如实供述了自己的罪行。对余某依法应如何量刑?()
输入一个整数和一棵二元树。从树的根结点开始往下访问一直到叶结点所经过的所有结点形成一条路径。打印出和与输入整数相等的所有路径。例如输入整数22和如下二元树10
有如下程序:#include#includeusingnamespacestd;classAnimal{public:virtualstring
A、Theshorterhourstheywork,thehigherpaytheycanenjoy.B、Themoretheywork,thelessleisuretheycanenjoy.C、Theshort
最新回复
(
0
)