Unit 3. Structure of Buildings

Before you read the text, discuss the following questions with your group mates or teacher.

1) Do you know what structural systems are?

2) What parts of a building can be made from wood?

3) How does laminated veneer lumber function?

4) What are I-joists used for?

5) What advantages do manufactured trusses have?

6) Why is steel one of the major structural materials?

7) What structural shape do you know?

8) How are steel frames erected at the building site?

9) What is in-situ concrete used for?

10)

Text: Structural Systems

The structures of buildings are mostly skeleton frames of various types. New domestic housing in many parts of the world today is commonly made from timber-made construction. Wood products are becoming a bigger part of the construction industry. They may be used in both residential and commercial buildings as structural and aesthetic materials. In buildings made of other materials, wood is still found as a supporting material, especially in roof construction, in interior doors and their frames, and as exterior cladding.

Laminated veneer lumber functions as beams to provide support over large spans, such as removed support walls and places where dimensional lumber is not sufficient, and also in areas where a heavy load is bearing from a floor, wall or roof above on a short span. Wood I-joists are used for floor joists on upper floors. They are engineered for long spans and are doubled up in places where a wall will bedaligned over them. Glued laminated beams are created by gluing the faces together to create beams. By gluing multiple, common sized pieces of lumber together act as one larger piece of lumber. Manufactured trusses are used in home construction as a prefabricated replacement for roof rafters and ceiling joists. It is seen as an easier installation and a better solution for supporting roofs as opposed to the use of lumber struts and purlins as bracing.

Steel is one of the major structural materials in buildings. It is a strong and stiff material. It can be quickly fabricated and erected. The lightest and most efficient structural shape is the bar (or open web) joist, a standard truss made with angles for the top and bottom chords, joined by welding to a web made of a continuous bent rod. It is used almost exclusively to support roofs and can span up to 45 meters. The standard rolled shape are frequently used as beams and columns, the wide flange, or W-shape, being the most common. Where steel beams support concrete floor slabs poured onto a metal deck, they can be made to act compositely with the concrete.

Reinforced concrete is also a major structural material in buildings. Insituconcrete is used for foundations and for structural skeleton frames.  

Precast concrete structural members are fabricated in the control conditions in a factory.

• GRAMMAR FOCUS

 Modal verbs                                                             Модальные глаголы

Choose the correct alternative

a) If you like, I can/may make an appointment for you to see Dr. Krall tomorrow.

b) Passengers mustn’t/don’t have to smoke while on board the plane.

c) Don’t let Sylvie climb that tree. She can/might fall.

d) You probably shouldn’t/mustn’t keep your passport in that pocket: it should/could easily be stolen.

e) I’m afraid Karen can’t/couldn’t come to the party tomorrow because she’s got flu.

f) Oh no! It mustn’t/can’t be seven o’clock already! Jill and Graham will be here in fifteen minutes!

g) I absolutely ought to/have to leave the house at six if I want to be at the station by six-thirty.

h) Be careful, that pot’s very heavy. You have to/could hurt your back.

Find the mistakes and underline them. Then write the correct sentences.

1. I can’t to come to your Christmas party next week.      I can’t come

2. Do you can ride a bicycle?

3. They say she cans run very fast.

4. Could they to go to the air show tomorrow?

5. We can’t visit the folk dance festival yesterday.

6. He didn’t can get to the school ball last Saturday.

Rewrite the sentences with perhaps or maybe, without changing the meaning.

1. I may play football next Saturday. (perhaps)

Perhaps I will play football next Saturday.

2. He might come with us to the New Year’s Dance. (maybe)

3. Chelsea might win the Champion League. (perhaps)

4. They may invite us to their engagement party. (maybe)

5. She might go to the Easter Races without you. (perhaps)

6. We may put up the Christmas decorations tonight. (maybe)

4. Write the rules by completing them with you must (+) or you must not (-)

1. drive on the left in Britain. (+)             You must drive on the left in Britain.

2. cross the road at the zebra crossing (+)

3. walk on the grass (-)

4. smoke inside the restaurant (-)

5. wear a seat belt when you drive (+)

6. go out without your identity card (-)

Tick the correct sentences.

1. a)(˅) Notice: Deep water. You must not swim here.

b)( ) Notice: Deep water. You don’t have to swim here.

2. a)( ) Mother: You mustn’t get up early tomorrow. There is no school.

b)( ) Mother: You don’t have to get up early tomorrow. There is no school.

3. a)( ) Teacher: You mustn’t run in the corridors. It’s dangerous.

b)( ) Teacher: You don’t have to run in the corridors. It’s dangerous.

4. a)( ) Policeman: You mustn’t drive so fast. It’s 50-km-per-hour zone.

b)( ) Policeman: You don’t have to drive so fast. It’s 50-km-per-hour zone.

5. a)( ) Classmate: You mustn’t give in your essay until Friday. There’s lots of time.

b)( ) Classmate: You don’t have to give in your essay until Friday. There’s lots of time.

6. a)( ) Judge: I’m banning you from driving for 12 months. You mustn’t drink and drive again.

b)( ) Judge: I’m banning you from driving for 12 months. You don’t have to drink and drive again.

Replace the phrases in bold with a modal verb phrase. Sometimes there is more than one possible answer.

1. Is it true that cats are able to see in the dark?     ______can______

2. It’s necessary for you to wear sunscreen when you go to beach. ________

3. It’s impossible for it to be that expensive. I’m sure there is a mistake. ______

4. Do you think it’s the right thing for me to buy Alex a birthday present?______

5. The doctor said I’m not allowed to lift anything heavy. ______________

6. It’s possible that we’ll be a bit late tonight. ________________

7. It’s not necessary for you to join the team if you don’t want to. ___________

8. Frank’s not in his office. I suppose it’s possible that he’s at lunch. _________

9. Come on, put those books away – it’s not a good idea for you to be studying at this time of night. ___________