填空题
When the Tacoma Narrows Bridge opened for traffic on 1 July 1940, it was celebrated as a major engineering achievement. Even before construction was completed, however, flaws in the design were apparent; workers sucked on lemon slices to avoid motion sickness as the structure swayed in the relatively mild winds. Engineers tried three different revisions during construction to address the vibration problem. Initially, tie-down cables were anchored to fifty-tonne bulkheads on the river banks. These were ineffective, as the cables soon detached. Then a pair of inclined cable locks was introduced to connect the main cables to the bridge deck at mid-span. These stayed throughout the bridge"s lifespan, but did nothing to reduce vibration. A further measure—the installation of hydraulic dampers between the towers and the floor system—was nullified because the dampers were compromised when the bridge was sand-blasted before painting.
Tacoma Narrows Bridge
-Disaster Strikes
-Disaster Strikes
When the Tacoma Narrows Bridge opened for traffic on 1 July 1940, it was celebrated as a major engineering achievement. Even before construction was completed, however, flaws in the design were apparent; workers sucked on lemon slices to avoid motion sickness as the structure swayed in the relatively mild winds. Engineers tried three different revisions during construction to address the vibration problem. Initially, tie-down cables were anchored to fifty-tonne bulkheads on the river banks. These were ineffective, as the cables soon detached. Then a pair of inclined cable locks was introduced to connect the main cables to the bridge deck at mid-span. These stayed throughout the bridge"s lifespan, but did nothing to reduce vibration. A further measure—the installation of hydraulic dampers between the towers and the floor system—was nullified because the dampers were compromised when the bridge was sand-blasted before painting.
填空题
Complete the notes below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
Write your answers in boxes 14-16 on your answer sheet.
Engineers used various techniques while building the bridge to reduce wobble:
● they attached ____1____ to heavy blocks on the shoreline
● they fastened main cables to the middle of the ____2____
● ____3____ were placed between the tallest parts of the structure and the deck.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
Write your answers in boxes 14-16 on your answer sheet.
Engineers used various techniques while building the bridge to reduce wobble:
● they attached ____1____ to heavy blocks on the shoreline
● they fastened main cables to the middle of the ____2____
● ____3____ were placed between the tallest parts of the structure and the deck.
填空题
Complete the table below.
Choose ONE WORD ONLY from the passage for each answer.
Write your answers in boxes 17-19 on your answer sheet.
Choose ONE WORD ONLY from the passage for each answer.
Write your answers in boxes 17-19 on your answer sheet.
| Mode of Vibration | Description | ||||||||||||||||||||||||||||||||||||
| 4 | moves repeatedly to the left and right | ||||||||||||||||||||||||||||||||||||
| 5 | up and down motion; like a wave | ||||||||||||||||||||||||||||||||||||
| torsional | resembles motions of a 6 | ||||||||||||||||||||||||||||||||||||
填空题
Complete the summary below.
Choose NO MORE THAN TWO WORDS from the passage for each answer.
Write your answers in boxes 20-24 on your answer sheet.
____7____ is a series of actions leading to torsional oscillation. Various components move back and forth from the force of the ____8____ . Eventually the structure absorbs more ____9____ than it is able to disperse and the ____10____ increase in intensity until the structure collapses under the ____11____ .
Choose NO MORE THAN TWO WORDS from the passage for each answer.
Write your answers in boxes 20-24 on your answer sheet.
____7____ is a series of actions leading to torsional oscillation. Various components move back and forth from the force of the ____8____ . Eventually the structure absorbs more ____9____ than it is able to disperse and the ____10____ increase in intensity until the structure collapses under the ____11____ .
填空题
Choose TWO letters A-E.
Write your answers in boxes 25 and 26 on your answer sheet.
Which TWO of the following were on the bridge at the time of the collapse?
A. filming equipment
B. a small dog
C. Leonard Coatsworth"s daughter
D. a vehicle
E. Professor Farquharson
Write your answers in boxes 25 and 26 on your answer sheet.
Which TWO of the following were on the bridge at the time of the collapse?
A. filming equipment
B. a small dog
C. Leonard Coatsworth"s daughter
D. a vehicle
E. Professor Farquharson