Добавил:
Upload Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз: Предмет: Файл:
Учебное пособие. Английский язык в профессии.docx
Скачиваний:
181
Добавлен:
09.06.2015
Размер:
796.93 Кб
Скачать

1) Find the equivalents:

world obstacles; sea currents; boundary dimensions; seabed silt; maintenance costs; bridge supports; weather conditions; railway tunnel; travel time

2) Choose the best variant:

1. There always was a choice between bridging and tunneling in … over or under a large waterway.

a) crossing b) crippling c) cruising

2. Bridges require lower maintenance … than tunnels.

a) corrosion b) corrugations c) costs

3. Tunnels are much … as compared to the bridge crossing.

a) saving b) saver c) safer

4. Weather conditions cannot influence the … through tunnels.

a) traffic b) transfer c) transit

5. The cost of the tunnel under the English … is enormous.

a) Cheddar b) Channel c) Canal

3) Find the opposites to the words:

gathering _____________

slow _________________

drawback_____________

allow_________________

bound (adj.) ___________

lessening _____________

small________________

shallow _____________

4) Are the sentences True or False? Correct the wrong ones:

1. ______ The Straits of Gibraltar separates Europe from Africa.

2. ______ The under clearance of the bridges must be over 60 m high not to prevent shipping.

3. ______ For the first time the Bosporus was bridged in 1973.

4. ______ Tunnels require lower maintenance costs.

5. ______ Vessels can navigate much easier if there are no bridges.

6. ______ The Bosporus bridge managed to withstand the wind blows up to 162 km per hour.

References: http://www.bris.ac.uk/civilengineering/bridges/Pages.html

Unit 3. Reinforced Concrete Bridges.

Vocabulary.

reinforced concrete — железо-бетон

possess — обладать

substitute — заменить

ribbed - ребристый

work in compression — работать на сжатие

reinforcement — арматура

competitive — конкурентоспособный

beforehand — заранее

prestressed — преднапряженный

jack—домкрат bughole — дыра

Concrete being an artificial stone possesses the same good qualities as natural stones. It works well in compression and bad in tension. That is why concrete has substituted natural stone in arch bridges because an arch works in compression.

At the beginning of the 19-th century concrete was reinforced by metal bars. The idea was to transfer the tension stress from the concrete to the reinforcement. This resulted in a new building material, which is known as reinforced concrete.

At present reinforced concrete bridges are widely spread because this building material is in line with short and medium spans (up to 40 – 60-m). It is also rather competitive with metal for long span structures.

The reinforced concrete spans are of a great variety because of their ability to work in compression and tension as well as flexure. It is used for producing simple beams, continuous beams, cantilever-beam systems, arches, frames and combined systems (arch + beam or arch + truss), etc.

The builders use monolithic reinforced concrete laid in situ, prefabricated reinforced concrete, which is made at the works beforehand and the bridge is assembled in-situ from the reinforced concrete segments. Prefabricated mon­olithic concrete is the combination of both mentioned types. To make the reinforced concrete highly strong and stiff it is prestressed by jacks and reinforcement of high strength wire.

Sometimes to re­duce the structure weight they substitute the most usual coarse aggregate such as crushed rock, pebbles, and gravel by slag and bloating clay. This results in light concrete.

In comparison with other building materials the bridges made of reinforced concrete offer the following advantages: a substantial saving of steel, which is scarce to supply; elimination of maintenance cost as compared with metal bridges; greater rigidity as against metal bridges; long useful life (80 – 100 years); the variety of structural forms improving bridge appear­ance and architecture.

The disadvantages of the reinforced concrete bridges may be the following: great dead weight; great labor-consuming character of the bridge segments producing; hidden bugholes may cause dangerous complications and they are difficult to be reconditioned; difficulties of concrete laying in winter.

Answer the questions:

1. Is there any difference between concrete and reinforce concrete?

2. What is the best length for the reinforced concrete spans and why?

3. What structural model is most preferable for the reinforced concrete bridges?

Exercises: