首页
登录
职称英语
"Engineering Class"[img]2012q1/ct_etoefm_etoeflistz_1501_20121[/img] [br] Which
"Engineering Class"[img]2012q1/ct_etoefm_etoeflistz_1501_20121[/img] [br] Which
游客
2025-02-08
37
管理
问题
"Engineering Class"
[br] Which technique is used to reinforce walls?
[Narrator] Listen to part of a lecture in an engineering class.
[Professor]
Because every earthquake presents us with unique conditions, it’s difficult to anticipate the stresses that
will ultimately affect the structures we design and build. So our challenge is to try to design a building Q46
that will be as... safe as possible... for all types of earthquakes. Besides that, during the past decade,
the expectations for earthquake-resistant structures have changed. Whereas in the past, it was considered
adequate for a building not to collapse during an earthquake, now insurance companies and...
and even clients... they’re demanding buildings that will be able to maintain their structural integrity
through an earthquake and, uh... remain sound... after the earthquake subsides.
So, in recent years were developed several techniques for building more earthquake-resistant Q46
structures: For relatively small buildings, all we have to do, really, is bolt the buildings to their foundations
and, uh... provide some support walls. Remember these walls are referred to as shear walls in
your textbook. They’re made of reinforced concrete, and by that I mean concrete with steel rods embedded
in it. This not only strengthens the structure but... but it also diminishes the forces that tend to
shake a building during a quake. And in addition to the shear walls that surround a building, shear walls
can be situated in the center of a building around an elevator shaft or a stairwell. This is really an excellent
reinforcement. It’s commonly known as a shear core, and it contains reinforced concrete, too.
Okay. Let’s talk about walls. Walls can also be reinforced, using a technique called cross-bracing Q47
Imagine steel beams that cross diagonally from the ceiling to the floor... and this happens on each
story in a building. So before the walls are finished, you can see a vertical row of steel x’s on the structure.
And this cross-bracing tends to make a building very rigid, and consequently, very strong.
But besides steel reinforcements, engineers have also devised base isolators, which are positioned
below the building, and their purpose is to absorb the shock of the sideways shaking that can undermine
a building and cause it to collapse. Most of the base isolators that are currently being used are made of Q48
alternating layers of steel and synthetic rubber. The steel is for strength, but, uh... the rubber absorbs
shock waves. In higher buildings, a... a moat... of flexible materials allows the building to sway during
seismic activity. Or... or large rubber cylinders support all of the corners of the building, and in
between each floor, and they allow the building to sway during an earthquake. So, you can see that
these alternatives are quite different from cross-bracing or shear walls.
So the combination of reinforced structures and flexible materials has been proven to reduce earth
quake damage. But even these engineering techniques are insufficient if the building has been constructed
on filled ground. Soil used in fill dirt can lose its bearing strength when subjected to the shock Q49
waves of an earthquake, and the buildings constructed on it can literally disappear into the Earth. So, in
areas where earthquakes are known to occur, it’s important to understand the terrain, and you have to
be sure that the ground is either solid or it’s been adequately prepared.
Okay, let’s assume that we do everything right... we choose and prepare the construction site and
we design a building with plenty of reinforcements and flexible materials. With cross-bracing, we probably Q50
have a building with the strength to holdup under earthquakes, even those of relatively high magnitudes.
And building, what about the occupants? Well, the structure may be
strong, but the furniture will probably be overturned or shifted during the earthquake and that could
result in major injuries for the people inside. So, now that we’ve made progress in solving the problem
of how to preserve the buildings, uh... one of the more recent areas of research is how to better protect
the occupants during an earthquake.
One interesting possibility is to design buildings that house a series of pistons, and these pistons Q51
are filled with fluid and controlled by sensors in a computer. So... by analyzing signals from the sensors,
the computer should be able to determine the magnitude of an earthquake in progress... and
when it does that, it can trigger electromagnets in the pistons to increase or decrease the... the rigidity
of the shock absorbers... built into the structure. If the earthquake is minor, then the building can be
programmed to sway gently, and the people and everything else inside get a safe ride. But during high-magnitude
earthquakes, the shock absorbers can freeze the building to prevent it from shaking at all. So
the beauty of the concept is that the computer sensors work very quickly, reacting within one one-thousandth
of a second, and they can run on battery power since the electrical system usually fails during an
earthquake. Will the concept work? Well, the National Science Foundation is supporting more research Q51
into the potential of pistons, and the results so far are promising.
选项
A、Cross-bracing
B、Shear cores
C、Bolting
D、Base isolators
答案
A
解析
Cross-bracing
转载请注明原文地址:https://tihaiku.com/zcyy/3947988.html
相关试题推荐
"EnvironmentalScienceClass"[img]2012q1/ct_etoefm_etoeflistz_1592_20121[/img][
"Professor’sOffice"[img]2012q1/ct_etoefm_etoeflistz_1586_20121[/img][br]What
"Professor’sOffice"[img]2012q1/ct_etoefm_etoeflistz_1586_20121[/img][br]What
"Professor’sOffice"[img]2012q1/ct_etoefm_etoeflistz_1586_20121[/img][br]Whyd
[img]2012q1/ct_etoefm_etoefspeaka_2094_20121[/img][originaltext]StudentAOh,
[img]2012q1/ct_etoefm_etoeflistz_0334_20121[/img][br]Whatisthepurposeofgr
[img]2012q1/ct_etoefm_etoeflistz_0334_20121[/img][br]Accordingtotheprofesso
[img]2012q1/ct_etoefm_etoeflistz_0334_20121[/img][br]Whydoestheprofessorsa
[img]2012q1/ct_etoefm_etoeflistz_0334_20121[/img][br]Whatdoestheprofessorm
[img]2012q1/ct_etoefm_etoeflistz_0327_20121[/img][br]Whatistheprofessor’so
随机试题
DespiteDenmark’smanifestvirtues,Danesnevertalkabouthowproudtheyar
SecretsofGrade-AParentsA)WhenCareyGrahamstartedGradeOne,hego
Thesungivesofflightandwarmth,______(这使植物生长变为可能)whichmakesitpossiblefor
运动神经纤维末梢释放Ach属于:( )A.主动转动 B.异化扩散 C.单纯
(2021年真题)在未获得董事会席位的情况下,股权投资基金有时会希望委派人员出任
关于股票质押式回购业务的相关规则,下列说法正确的是()。A.证券公司代理进行
男性,54岁,既往有哮喘及冠心病史,咳嗽咳痰喘息来急诊室。体检:BP140/90
根据我国《担保法》的规定,不得抵押的财产有( )A.土地所有权 B.抵押人所
有机磷中毒时,可使A.胆碱酯酶活性减少 B.胆碱酯酶活性增加 C.乙酰胆碱释
下列影响施工质量的因素中,属于材料因素的有()。A.计量器具 B.工程设备
最新回复
(
0
)