8. Match the definitions with the appropriate words.

1. shell a) connected pieces forming the lower part of a truss

2. truss b) sloping unit of a truss

3. top chord c) units, assembled in three dimensions

4. bottom chord d) vertical piece of a truss

5. strut e) spanning and space-enclosing element

6. post f) element consisting of a series of triangles lying

in one plane

7. joints h) connected pieces forming the upper part of a truss

8. space frame g) place where individual pieces of a truss intersect at

9. Fill in the gaps with the words from the text.

1. А shell is a spanning and space-enclosing element of … form.

2. A shell has got a thickness less than was usual for the … and mass-concrete forms.

3. Straight pieces of metal or timber form a series of triangles lying in a single … .

4. A triangle cannot be … by stress.

5. The most important … are lighter framed equivalents of domes and vaults.

6. The ribs in fully developed timber-framing systems were aligned radially and … .

7. The shell, together with the … tensile membrane or cable net, will continue to play an important role.

10. Replace the words in bold type into their contextual synonyms given below.

1. The usual role in a building is carrying a roof - in place of the dome, vault, beam, or slab.

2. A triangle cannot be distorted by stress.

3. The individual pieces intersect at truss joints.

4. The joints of a space frame need not be rigid.

5. The most important space frames are lighter framed equivalents of domes or slabs spanning in two or more directions simultaneously.

6. In fully developed timber-framing systems the ribs were aligned radially and circumferentially.

7. A truss is a structural member usually fabricated from straight pieces of metal or timber

(stiff, at the same time, produced, to be arranged in a line, to be deformed, tie, supporting)

11. Answer the questions to the text.

1. What is a shell?

2. What is its purpose?

3. How it may be curved?

4. What requirements should be taken into consideration when it is necessary to achieve the reduction in thickness?

5. What does the term ''truss'' mean?

6. What are the elements of the truss?

7. What is a space frame?

8. How is a load at any point of the space frame distributed?

12. Identify the type of the given trusses. Explain the difference between the Pratt and the Warren truss systems.

13. With your partner, discuss the main features of trusses and space frames. Use the following words and word combinations.

The assemblies of linear members; axial tension or compression; ties; three-dimensional; to be distributed in all directions; the true timber truss; wrought iron; space frames; the rib; to be aligned radially and circumferentially; the outer covering; to be regarded as; airframe structures; the most efficient use of material.

Unit 7 Roofs

Text: Roofs

Grammar:

• Modal verbs and their equivalents (Синявская, p. 404 – 406)

• Word-forming suffix of nouns: -ing