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Read the dialogues. Point out new and important information for you
A.: What did the early houses in Great Britain look like?
B.: Most of them were round and built of wood.
A.: Do you know whether those houses were plastered?
B.: Sure, they were. A plastered house is warmer and looks nicer.
A.: How did the light come into those early houses?
B.: Well, as you know, there were no windows in such houses.
A.: What do you mean?
B.: That’s exactly what I mean: those early houses had no windows.
A.: Then how did the light come in? Through the roof?
B.: Yes, through the roof. There was a special hole in the roof for that purpose.
A.: I suppose they covered up the hole when it rained.
B.: Right you are! It’s exactly what I was going to tell you.
A.: There was a time when the height a building was limited to four and five storeys, wasn’t they?
B.: You are quite right! There was such a time.
A.: Do you happen to know the reason why that was so?
B.: It was so because the walls of a building had to carry the whole framework and the roof of a building.
A.: At present the frame carries the walls, doesn’t it?
B.: Sure, it does. A structural steel framework has completely done away with the need for thick masonry walls.
A.: It looks as if the primary function of walls in general has been changed.
B.: Definitely so. Builders of high-rise structures rest the walls of the structure independently upon a so-called skeleton.
A.: Do you think the walls of such a building could be built from the roof downward?
B.: Why not? They no longer support the structure. The walls are, so to say, no more than curtains.
Perform the conversation in pairs. Then make up your own dialogues
Read the text and tell about forces acting on any member of a building. Answer the question: What kind of stresses do you know?
Text 3 B
The ultimate purpose of building is to create a stable structure. In mechanical terms, structures are stable when all their parts are in a state of equilibrium, or rest. Walls and roofs can buckle, crack, or collapse if they are not properly designed. These movements are caused by forces that tend to push or pull bodies in a given direction. Forces acting on any member (part) of a building are, first, its own weight and, second, furnishings, wind, etc. Their action encounters a reaction in opposing forces that hold the member in place by resisting at its joints. These forces may be active in all directions, and they must be balanced for stability. They tend to crush, pull apart, and bend the member – in other words, to change its size and shape.
Within the member itself there are forces, too, that tend to resist any deformation. They are called stresses, and they very according to the strength of materials and the form of the member. The kinds of stress under consideration are compression, which resists crushing; tension, which resists pulling apart; and bending, which occurs when one part of a member is in compression and the other is in tension.
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