Архитектура Аудит Военная наука Иностранные языки Медицина Металлургия Метрология
Образование Политология Производство Психология Стандартизация Технологии
VI. Make the precis of the text
Text 5. CABLE-STAYED BRIDGES
Cable-stayed bridgesresemble suspension bridges. Both have roadways that hang from cables, and both have towers. In a cable-stayed bridge, however, the cables that support the roadway are connected directly to the towers.
A cable-stayed bridge may be used if its foundation can support only one tower. Most cable-stayed bridges have three spans, but some have one tower and two spans. The most efficient cable-stayed bridges have a main span about 700 feet (210 meters) long.
The cables of a cable-stayed bridge may be linked from the roadway to the towers in several ways. The cables may extend from various points on the roadway to the tops of the towers, forming a radiating pattern. The cables form a fan pattern, also called a harp pattern, if they are connected from a variety of points on the roadway to several points on the towers. It the cables are attached from one point on the roadway to various points on the towers, they form a star pattern.
Moveable bridges have a roadway that is moved entirely or partially to provide enough clearance for large ships to pass. There are three types of moveable bridges, bascule bridges, vertical lift bridges, and swing bridges. A bascule bridge tilts upward to open. Some bascule bridges open at one end, and others the middle. A vertical lift bridge has a roadway that extends between two towers. The roadway rises between the towers, and ships pass underneath. A swing bridge is mounted on a central pier. The bridge swings sideways to enable ships to pass.
Vertical lift bridge
I. Decide whether the following statements are true or false according to the text:
1. Cable-stayed bridges resemble cantilever bridges.
2. In cable-stayed bridge the cables that support the roadway are connected to the towers.
3. A cable-stayed bridge may be used when its foundation can support two towers.
4. Most cable-stayed bridges have 3 spans and two towers.
5. The cables may be linked from the roadway to the towers in several way.
6. If the cables are connected from a variety of points on the roadway to several points on the towers, they form a star pattern.
7. There are four types of moveable bridges.
8. A bascule bridge tilts backward to open.
9. A vertical lift bridge has a roadway that extends between two towers.
10. A swing bridge is mounted on a central tower.
II. Answer the questions:
1. What type of bridge do cable-stayed bridges resemble?
2. How are cables connected?
3. What is the design of most cable-stayed bridges?
4. When do the cables form a fan pattern?
5. When do the cables form a star pattern?
6. What are the types of moveable bridges?
7. How do bascule bridges operate?
8. Where is a roadway situated in a vertical lift bridge?
9. Where is a swing bridge mounted?
10. Why does it move sideways?
III. Insert the words from the list:
cables, speed, anchorages repair, waterways, impractical, intermediate-length, variation, lower cost, replacement, traffic, costly, frame, spans
1. Cable-stayed bridges represent a ... of the suspension bridge.
2. A cable- stayed bridge is constructed in much the same way as a suspension bridge is, but without the main … .
3. Cable-stayed designs are used for … spans.
4. Advantages the cable-stayed bridge has over a standard suspension bridge include a … construction and … since … are not necessary.
5. There are no massive cables, as with suspension bridges, making cable … or …simpler.
6. Movable bridges are usually found over heavily traveled ….
7. A vertical-lift bridge consists of a rigid … held between two tall towers.
8. Moveable bridges are generally constructed over waterways where it is either … or too … to build bridges with high enough clearances for water … to pass underneath.
9. Vertical-lift bridges are useful for longer …, but they must be built so they can be lifted high enough for tall ships to pass underneath.
IV. Fill the correct preposition:
to hang … sth, to be connected … sth, to be linked … sth, to extend … sth, the top … sth, to be attached … sth … sth, to be mounted … sth
V. Fill in the gaps with a suitable derivations of the word given on the right:
Последнее изменение этой страницы: 2016-03-16; Просмотров: 451; Нарушение авторского права страницы