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.