Text a. Trusses

The Romans also used another structural type that has proved basic to large construc­tions in the nineteenth and twentieth cen­turies – the truss. The traditional truss was made up of timbers arranged in triangular shapes or cells.

The triangle, by virtue of its built-in geometry, cannot be changed in shape without distorting or bending one of its sides. Hence, by adding triangle to tri­angle, it is possible to construct extended figures that are quite strong despite being relatively light. Wooden trusses were used in a wide variety of forms for roof construction in Roman buildings and continued to be used during the Middle Ages. One superb example of medieval wooden truss construction is the hammer-beam truss roof of Westminster Hall, London, built in 1394-99 by Henry Yevele and Hugh Herland and spanning 68 feet (20.7 meters); it is the broadest wooden span of medieval times. The great Gothic cathedrals such as Amiens were covered by such a wooden roof over the rib vault.

During the nineteenth century, many new forms of trusses were devised, often identified by the name of the engineer who first used them. The truss, particularly when built up of steel members, proved capable of great spans, and hence was used to enclose vast spaces. An example is the Galerie des Machines, the largest of the buildings in the international exhibition held in Paris, in which a series of curved arch trusses spanned 377 feet (114.9 meters). Here, as with any arch, there were considerable lateral forces at the base, but massive buttresses were made unnecessary because the ends of the arched trusses were connected by steel rods just beneath the floor.

Exercise 4. Translate the words:

prove, identify, truss, timber, roof, rib, span (v., n.), member, cathedral, type, shape, cell, bend, distort, arrange, form (v., n.).

Exercise 5. Choose the right translation from A to B:

A: arrange, devise, despite (in spite of), triangle, use, construction, span, form, vault, exhibition.

B: несмотря на, изобретать, треугольник, строительство, форма, использовать, пролет, свод, размещать, выставка.

Exercise 6. Are these meanings correct or incorrect? Correct the mistakes:

distort – размещать

bend – соединять

devise – поддерживать

member – главный

cathedral – церковь

cell – ячейка

roof – крыша

from – форма

capable of smth (doing smth.)

timber – бетон

steel – железо

beam – стержень

Exercise 7. Translate the following word combinations:

structural type, triangular shape, built-in geometry, roof construction, the Middle Ages, medieval wooden truss construction, hammer-beam truss roof, rib vault, steel members, curved arch trusses, massive buttresses, steel rods.

Exercise 8. Read and translate text B with a dictionary. Write a summary of the text.

Text b.

Many new materials are familiar to us over centuries. We are pretty well acquainted with the advantages and disadvantages of wood. We know that glass is transparent, but in some ways it is rather brittle. Glass has the advantages of cheapness, rigidity and chemical inertness. We are aware that most metals can stand severe handling, but some of them rust. But such materials as plastic materials are not found in nature. Some years ago plastics were little more than laboratory curiosities. Today plastics are conceived in the laboratory of the chemical plant. But plastic is formed by extrusion or injection molding under very high pressure. It can be molded into any desired shape. Organic plastics are divided into two general groups: thermosetting and thermoplastic. The thermosetting group becomes rigid through a chemical change that occurs when heat is applied. These plastic cannot be remolded. The thermoplastic group remains soft at high temperatures and must be cooled before becoming rigid. This group is not used generally as a structural material. Plastics are rapidly becoming important construction materials because of its great variety, strength, durability and lightness. The high strength to weight ratio of some plastic offers big field in the coming age of space travels and rockets. Plastics are light. The same benefits of light weight coupled with good strength and absence of corrosion offer tremendous potential as alternative to traditional building materials. A given volume of polythene weighs less than one-eighth of an equal volume of iron and less than half of the same volume of aluminum. The following of plastics are usually shared by all plastics lightweight, corrosion resistance, electrical and thermal insulation.

Exercise 9. Translate from English into Russian. Define the syntax functions of the underlined words.

1. The Romans also used another structural type.

2. The traditional truss was made up of timbers arranged in triangular shapes or cells.

3. The triangle cannot be changed in shape.

4. It is possible to construct extended figures that are quite strong.

5. Wooden trusses were used in a wide variety of forms for roof construction in Roman buildings and continued to be used during the Middle Ages.

6. It is the broadest wooden span of medieval times.

7. During the nineteenth century, many new forms of trusses were devised, often identified by the name of the engineer who first used them.

8. Wooden trusses were used in a wide variety of forms for roof construction in Roman buildings and continued to be used during the Middle Ages.

Exercise 10. Translate the words:

ферма, древесина, размещать встроенный, искажать, сгибать, крыша, ребро, определять, элемент.

Exercise 11. Note in the texts of this unit:

1. Noun groups

2. Modal verbs

3. Participle II

4. ing-forms