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?
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 bed aligned 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. In-situ concrete 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
| Modal verbs | Ways of using | Examples | Equivalents | Ways of using | Examples |
| Can/could | Выражает: a)умение b) разрешение c) вероятность в настоящем или в будущем | She can speak fluent German. Can/could I interrupt for a moment? Of course, I could be wrong. | Be able to (am/is/are/ was/were able to) | Выражает: a)умение b) разрешение | She is able to speak fluent German. Am I able to interrupt for a moment? |
| May/Might | Выражает: a) разрешение (в первом лице: формальный стиль) b) вероятность в настоящем или в будущем | May I speak to you for a moment? There may be a storm later. | Be allowed to(am/is/are/ was/were allowed to) | Выражает: a) разрешение | She is allowed to go to parties on weekends. |
| Must | Выражает а) обязанность б)запрет в) логическую необходимость | I must go home now. It’s late.(=I have decided this) You mustn’t smoke in here. He’s not answering his phone. He must be in a meeting. | Have to /have got to Don’t have to Should/ shouldn’t =Ought to/ought not to | Выражает необходимость в силу обстоятельств (приходится, нужно) Выражает совет, пожелания | I’ve got to be at work early tomorrow morning. (=my boss decided this, I have an early meeting) You don’t have to buy a ticket if you don’t want to. You should be in bed by now. (=this is the right thing). =You ought to be in bed now. You shouldn’t eat so much chocolate. (=it’s not a good idea). |
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