1) Find the equivalents:

железобетонный мост

заменять, замещать

пред напряженная арматура

заранее

обычная арматура

плитное пролетное строение

ребристое пролетное строение

раскос

жесткий нижний пояс балки

стенка

шпала

отверстия

отогнутый

домкрат

сварочная сталь

2) Choose the right answer:

1. Concrete has substituted natural stone in arch bridges because

A it works well in tension.

B it works well in bending.

C it works well in compression.

D it works well in torsion.

2. Prefabricated mon­olithic concrete is…

A. usually called monolithic reinforced concrete.

B. the combination of monolithic reinforced concrete and prefabricated reinforced concrete.

C. usually called prefabricated reinforced concrete.

D. the combination of monolithic reinforced concrete and prestressed concrete.

3. The disadvantages of the reinforced concrete bridges are

A a substantial saving of steel; elimination of maintenance cost; greater rigidity.

B the variety of structural forms; difficulties of concrete laying in winter; hidden bugholes.

C hidden bugholes; a substantial saving of steel; elimination of maintenance cost.

D great dead weight; difficulties of concrete laying in winter; hidden bugholes.

3) Divide the words into pairs:

metal

high-strength

bug

concrete

structure

prestressed

laying

wire

bar

concrete

holes

weight

4) Fill in the blanks:

erected, reinforced, design, spans, longest, are

1. The longest spans among lattice trusses … 63m in Russia.

2. The first concrete arch bridge was … in France in 1875.

3. The first … concrete bridges were constructed in 1877.

4. The earliest Russian reinforced concrete beam bridge was built to professor Belelyubsky’s … in 1893.

5. The … spans among continuous beam systems are 105 m in Japan.

6. The longest … among arch bridges are 228 m in the Ukraine.

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

Unit 4. Beam bridge.

Vocabulary.

Beam - балка

Compression – сжатие, компрессия

Tension - напряжение, натяжение, давление

Twisting – закручивание, скручивание

Bending – изгибание, кривизна

Tensile – прочность растяжения при изгибе

To span – соединять, протягиваться,

Dissipate – распределять, уменьшать

Piling – отсыпка, грунт

Daisy-chaining – последовательное соединение, гирляндная цепь

Lead-in

1. What is a bridge? What obstacles are usual to cross?

2. How long can bridges be? How do bridges differ?

3. What types of bridges according to their functions can you name?

4. Look at the illustrations. Which types of bridges do they match?

A.	E.
B.	F .
C.	G.
D.	H.

A beam bridge, sometimes called a girder bridge, is a rigid structure that consists of one horizontal beam supported at each end, usually by some kind of pillar or pier. In structural terms, it is the simplest type of bridge and is a popular selection because of its inexpensive construction costs. It began as a felled log supported by opposing river banks that was used to span a river or other body of water. Today, it is commonly made fromreinforced concreteorsteel beamsfor everything from pedestrian bridges to highway overpasses.

This type of bridge works on the principles of compression and tension, that’s why it needs a strong beam to resist twisting and bending under the weight it must support. When a load, for example a group of traveling cars, pushes down on the beam, the weight of the beam pushes down on the piers. The beam's top edge is pushed together as the result of compression, and tension causes the bottom edge to stretch and lengthen. The top reaches maximum compression while the bottom snaps under too much tension.

Many beam bridges for road construction are made from concrete and steel because these materials are strong enough to bear the forces of compression and tension. The distance a beam can span is directly related to its height, because higher beams offer more material to dissipate tension and need reinforcement.

In spite of reinforcements like concrete, steel, and trusses, this type of bridge is limited by its length, so they rarely span more than 250 feet (76.2 m). But daisy-chaining bridge sections allow to reach longer distances. One of the world's longest bridges is a continuous span beam bridge. It’s located in Louisiana as a pair of parallel bridges of the Lake Pontchartrain Causeway that measure almost 24 miles (38.5 km) long and are supported by 9,500 concrete pilings.

Answer the following questions:

1. What does a beam bridge consist of?

2. What loads does a beam carry by bending?

3. What materials are frequently used in beam bridge construction? Why?

4. Where are beam bridges most commonly used?

5. What does the distance of a span related to? Why?

6. What the world's longest beam bridges do you know?

Exercises: