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2023年全國碩士研究生考試考研英語一試題真題(含答案詳解+作文范文)_第1頁
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1、<p>  Shake Table</p><p>  A shake table can be used to test the resistance of structures to seismic shaking. It can also be used to demonstrate the sensitivity of structures of different heights to the

2、 frequency of the ground motion.</p><p>  The shake table pictured below, which was designed and built by John Lahr with expert advice from Tom Tompkins.  It is based on a lightweight platform that is c

3、onstrained to move in just one direction. The platform is made from a 10 inch by 10 inch piece of foam-core board. Hollow metal tubes are connected to the left and right edges with hot glue. Metal rods (made from welding

4、 rods) are slid through the tubes and the ends of the rods are held firmly by wooden blocks. The blocks are hot glued to</p><p>  Click for larger image </p><p>  At this point in the constructi

5、on, the shake table platform is able to slide about an inch back and forth on the rods. It should move freely, without binding on the rods. </p><p>  I use a variable speed drill to shake the table. An alter

6、native to a variable speed drill is a single speed drill connected to an electronic speed control, such as the one sold by MLCS Ltd.  Their speed control unit is shown on their web site:  http://www.mlcswoodwor

7、king.com/Pages/speedcon.html , or they may be contacted at 1-800-533-9298.</p><p>  WARNING:I want to thank Greg Nowak (gregorysroom@yahoo.com) for the message that he sent on 2/22/2001 from  conc

8、erning leaving the shake table running for a long period of time.  The table should not be operated unattended and the 110 V power should always be disconnected when not in use.</p><p>  Paraphrasing Gr

9、eg: "There should be a big warning on any plans for an earth quake  simulation mechanism that uses a motor of any sort, as it could be dangerous if  not designed and operated properly.  About 10 years

10、 ago at a Cal Poly State University SLO open house (Poly Royal) an Architecture or Engineering student used a power drill set on low speed and left his earthquake machine running. It overheated and a fire erupted that ba

11、sically burned down a few class rooms."</p><p>  A rod with a U-shaped bend is mounted parallel to one side of the platform so that it is free to rotate. One end of a stiff wire is bent in a loop around

12、 the bottom of the U while the other end is shaped like a hook and is attached with strapping tape to the edge of the table.  A more durable and flexible alternative to strapping tape is to attach a square piece of

13、automobile inner tube with dimensions of about 2 x 2 inches to the edge of the table.  The rubber is folded over and glued to the to</p><p>  This arrangement will cause the platform to move back and fo

14、rth as the rod is rotated. The variable speed drill is attached to the rod by its chuck. The handle of the drill is also firmly attached to the plywood base. </p><p>  Construction details are posted for two

15、 shake table designs.</p><p>  To demonstrate the need for a diagonal element to give a wall shear resistance, I use 6-inch long pieces of wood or plastic with magnets mounted at each end. I have attached Ve

16、lcro to the platform and mating Velcro to a "base block." The base block has magnets mounted at each end. A basic wall, consisting of two verticals and a horizontal element, can be built on the base. This wall

17、will fall down during an earthquake. If, however, a diagonal element is added (made from a longer magnet stick, wh</p><p>  I usually provide one long magnet stick to be used as the diagonal and three short

18、magnet sticks and challenge the students to build a strong wall. Eventually they discover that a diagonal element is crucial. </p><p>  Here is a photograph of the shake table. To the left of the table is a

19、 piece of plastic (cut from a fluorescent light diffuser) with four "fingers" of varying length. When this is vibrated on the shake table, one can experiment with the effect of shaking frequency on the amplitud

20、e of motion of "buildings" of varying heights. </p><p>  Below are three photos of the shake table:  one with the magnetic sticks and two with a flexible building.</p><p>  Click

21、here for some additional information on use and construction of "magnetic sticks."</p><p>  At the May, 2000, open house of the USGS in Menlo Park, CA, Bob Page demonstrated some additional buildin

22、g issues using the shake table.   (Click to enlarge) </p><p>  He added some posts to one side of the building so that a string could be wrapped to form x-braces for each floor.  Below

23、are pictures of the building with and without the </p><p>  x-bracing.    (Click to enlarge) </p><p>  Bob also demonstrated a design feature of some modern buildings, namely &q

24、uot;base isolation."  The foundation of a building with base isolation allows the ground to move rapidly back an forth while the building stands nearly still.  To illustrate this, Bob used two jars partly

25、filled with water.  One was attached firmly to the shake table </p><p>  while the other was allowed to slide back and forth within a plastic tray.       (Click to enlarge) &l

26、t;/p><p>  Click HERE for some more information on base isolation.</p><p>  Classroom Exercises that use a Shake Table</p><p>  Larry Braile, a Purdue University seismologist, has deve

27、loped a fun classroom contest in which groups of 4 or 5 students design, build, and test buildings.  Although each group starts with the same construction materials, it's amazing how many different designs resul

28、t!  Also, check out Larry's other projects at Purdue. </p><p>  Instructions for building "water towers." </p><p>  Simulating wood-frame, masonry, and steel frame buildings:

29、ideas from MCEER (Multidisciplinary Center for Earthquake Engineering Research). </p><p>  Shake Tables in the Classroom</p><p>  Each year Frank Devereaux and Dan Argentar use a shake table to

30、test the building skill of their students during their unit on plate tectonics.  Here are some photos of the shake table being used in 2000 and 2001.  Dan has created an extensive web site with detailed informa

31、tion on this unit to aid any other teachers who may want to provide a similar unit of study.</p><p>  Other Shake Tables</p><p>  Coral Clark suggests, "Here is a link to a shake table that

32、 uses 4 rubber balls, 2 rubber bands, and 2 stiff boards (such as cut apart binders or thin plywood scraps).  It is about as simple as you can get for preliminary investigations. "http://www.raft.net/resources

33、/ideas/Shake%20Table.pdf   </p><p>  Dennis Ambrisco, Eleanor Omdahl, and I developed a display at the Denver Federal Center that includes two shake tables. </p><p>  Check out this g

34、reat site from IDEERS for more information and science projects related to earthquake resistant design. </p><p>  The Exploratorium also has shake table plans and links to additional sites.</p><p&

35、gt;  Here's a story and video about a huge shake table!SAN DIEGO, April 28, 2000 ?The two-story home twisted and creaked, books fell from a shelf, light fixtures swayed and a flower pot crashed to the ground as a ma

36、jor earthquake rocked a university laboratory. </p><p>  Damage Examples</p><p>  Ferndale, California, 1992</p><p><b>  振動臺</b></p><p>  振動臺能用來測試建筑物對于

37、地震振動的抵抗力,也能用來表明不同高度建筑物對地面運動頻率的靈敏度。</p><p>  下面是振動臺的圖片,它是有John Lahr并且加上Tom Tompkins的專業(yè)建議所設(shè)計和建造的。它是基于一個被限制只能向一個方向移動的輕質(zhì)平臺。這個平臺是有一10*10英寸大小的泡沫型心板做成的??招慕饘俟苁怯脽崮z連接左右兩邊的。金屬桿(已制成的焊接桿)是在空心金屬管中滑動的,桿的末端被木制的塊牢牢地栓住。木塊被熱膠粘

38、在夾板底部。</p><p>  用建造的觀點來看,振動臺平臺是能夠在桿上來回滑動的。它沒有固定在桿上,應(yīng)該自由移動。</p><p>  我在振動臺上使用了一個變速鉆孔機。對變速鉆孔機的一個選擇是一個單一速度的鉆孔機連接一個電子控速裝置,比如MLCS有限公司出售的一臺。他們的速度控制個體被展示在他們的網(wǎng)站上,網(wǎng)址為:http://www.mlcswoodworking.com/Page

39、s/speedcon.html,或撥打1-800-533-9298能聯(lián)系到他們。</p><p><b>  警告:</b></p><p>  我想要感謝Greg Nowak(gregoyroom@yahoo.com)因為他在2001年2月22日發(fā)布的關(guān)于長時間遠離運行著的振動臺的消息。振動臺不應(yīng)該在沒有人看管的情況下運作,而且在沒有使用的情況下,110伏的電壓應(yīng)該

40、被斷開。</p><p>  Grey解釋說:“在任何關(guān)于地球地震模擬裝置的計劃上應(yīng)該有嚴重的警告,使用任何種類的發(fā)動機,同樣地如果沒有適當?shù)卦O(shè)計和操作它可能是危險的。大約在10年前在Cal Poly</p><p>  State 大學(xué)SLO開放室(Poly王室的),一個建筑或工程學(xué)生使用一個設(shè)置在低速擋的電力鉆孔機,然后他離開了他的正在運行的地震儀。它由于過熱而噴出火把那很稀少的教室基

41、本上燒成平地?!?lt;/p><p>  U型桿被水平地裱好在平臺的一邊,所以這一邊能自由的旋轉(zhuǎn)。硬金屬絲的一端被彎曲成一個環(huán)并繞在U型桿的底部,同時另有端被彎成一個鉤,它被聯(lián)接帶連接在振動臺的邊緣。選擇一個更持久和更有韌性的聯(lián)結(jié)帶是用于連接汽車內(nèi)部的帶有立體感的大約2*2英寸的正方形管與振動臺的邊緣的。橡膠被折疊并粘在振動臺的頂部和底部的。熱膠能夠很好的為我工作。讓大于3/的橡膠粘住超出振動臺的部分,并燒一個洞穿過

42、這部分,然后硬金屬絲被彎曲穿過這個洞并插入橡膠中。</p><p>  這種排列將導(dǎo)致平臺來回移動隨桿的旋轉(zhuǎn)。變速鉆孔機由它的夾盤與桿連接。鉆孔機的把手也被膠合板底座緊緊連接。</p><p>  振動臺的兩種設(shè)計的建造詳細資料被記錄著。</p><p>  為了表明對角線要素對墻壁的抗剪力的需要,我使用6英寸長的兩端用磁鐵裱好的木塊或塑料塊。我把Velcro粘在平

43、臺上,使Velcro與底座塊相配。底座的每一端都用磁鐵裱好?;緣Ρ谑怯卸怪本€和一水平線要素組成,它是被建立在底座上的。這墻在地震中將會倒塌。但是,如果加上對角線要素(已制成的較長的磁鐵棍,這已被提供),這時墻將抵抗強烈地振動。</p><p>  我經(jīng)常提供一長磁鐵棍去作對角線和三個短磁鐵棍,并且挑戰(zhàn)學(xué)生去建造堅硬的墻壁。最后他們發(fā)現(xiàn)對角線要素是至關(guān)重要的。</p><p>  這里有

44、振動臺的照片。</p><p>  左邊的振動臺是一塊塑料(拍自攝影師)帶有可改變長度的四“手指”。當它在振動臺上振動時,它能測試在可改變高度的“建筑物”的廣闊運動上的振動頻率的影響。</p><p>  下面是振動臺的三張照片:一個帶有磁鐵棍和兩個帶有柔性的造型。</p><p>  2000年5月,在Menlo公園的USGS的開放室,CA Bob Page闡明一

45、些額外的使用振動臺的建造論文。</p><p>  他增加了一些關(guān)于建筑物的一面的記錄,所以這一系列為每一層可能被包裝成X-支柱。下面是帶有和不帶有X-支柱的圖片。  </p><p>  Bob也闡明一些現(xiàn)代建筑的一個設(shè)計特性,既“底部隔離”。一個帶有底部隔離的建筑物的地基允許地面快速來回的移動。而建筑物卻幾乎靜止不動。為了說明

46、著,Bob使用了兩個罐子。一個緊緊的粘在振動臺上而另一個裝在一個塑料盤里被迫來回滑動</p><p>  使用振動臺的教室練習(xí)</p><p>  Larry Braile是Purdue大學(xué)的一個地震學(xué)家,他發(fā)展一個娛樂教室比賽,在比賽中4個或5個人一組,這些學(xué)生設(shè)計,建造和測試建筑物。雖然每一組用同樣的餓建筑材料開始,但是驚奇的是設(shè)計的結(jié)果是多么的不同!</p><p

47、>  “水塔”建筑的介紹。</p><p>  模擬木造的,石造的和鋼造的建筑:來自MCEER(地震工程研究的多學(xué)科中心)的點子。</p><p><b>  教室里的振動臺</b></p><p>  Frank Devereaux和Dan Argentar每年都會用一臺振動臺來測試他們的學(xué)生在他們各自的盤子建筑學(xué)中的建筑技能。這里是一

48、些在2000年和2001年曾被使用過的振動臺的照片。Dan建立了一個廣大的網(wǎng)站,在這個單元上有詳細的信息去幫助其他可能想提供相似的學(xué)術(shù)的教師。</p><p><b>  其他的振動臺</b></p><p>  Coral Clark建議,“這是振動臺的一個環(huán)節(jié),這個振動臺使用了4個橡皮球,2個橡皮帶和2塊硬木板(例如剪切夾或薄夾板片)。它大概就和你能夠獲取的預(yù)備調(diào)

49、查一樣簡單。</p><p>  Dennis Ambrisco,Eleanor OmdahlHE 我在包含有兩臺振動臺的Dennis Federal中心開拓了一個展示。</p><p>  從大網(wǎng)站IDEERS可以獲得更多與地震抗震設(shè)計有關(guān)的信息和科研項目。</p><p>  勘探對也有振動臺計劃而且與另外的網(wǎng)站連接。</p><p> 

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