Find in Text 7A the paragraph saying about reinforced concrete regarded as one of the major structural materials in buildings and translate it into Russian.

Read aloud paragraph 6 of Text 7A.

Explain the following references.

a) They may be used in both residential and commercial
buildings as structural and aesthetic materials.

What does the pronoun they refer to?

b) They are engineered for long spans and are doubled up in
places where a wall will be aligned over them.

What does the pronoun they refer to?

c) It is a strong and stiff material. What does the pronoun // refer to?

d) // can be quickly fabricated and erected. What does the pronoun it refer to?

e) It is used almost exclusively to support roofs What does the pronoun it refer to?

f) they can be made to act compositely with the concrete. What does the pronoun they refer to?

g) These include beams of rectangular cross section, hollow
floor slabs, and single- and double-stem T shapes.

What does the pronoun these refer to?

 

Underline or mark the main ideas of Text 7A and retell it in English.

19. Skim Text 7B "Beams" and try to understand what it is about and what information is known to you.

•TEXT 7 В

Beams

A beam is a structural element that is capable of withstanding load primarily by resisting bending. The bending force induced into the material of the beam as a result of the external loads and external reactions to these loads is called a bending moment.

Beams generally carry vertical gravitational forces but can also be used to carry horizontal loads (i.e. loads due to an earthquake or wind). The loads carried by a beam are transferred to columns, walls, or girders, which then transfer the force to adjacent structural compression members.

Beams are characterized by their profile (the shape of their cross-section), their length, and their material. In contemporary construction, beams are typically made of steel, reinforced concrete or wood. One of the most common types of steel beam is the I-beam or wide-flange beam (also known as a universal beam or, for stouter sections, a universal column). This is used in steel-frame buildings and bridges. Other common beam profiles are the C-channel, the hollow structural section beam, the pipe, and the angle.

Internally, beams experience compressive, tensile and shear stresses as a result of the loads applied to them. Typically, under gravity loads, the original length of the beam is slightly reduced to enclose a smaller radius arc at the top of the beam, resulting in compression, while the same original beam length at the bottom of the beam is slightly stretched to enclose a larger radius arc, and so is under tension. Above the supports, the beam is exposed to shear stress.

6. Зак. 312

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UNIT 7. STRUCTURAL ELEMENTS | 163

 

There are some reinforced concrete beams that are entirely in compression. These beams are known as prestressed concrete beams, and are fabricated to produce a compression more than the expected tension under loading conditions. High strength steel tendons are stretched while the beam is cast over them. Then, when the concrete has begun to cure, the tendons are released and the beam is immediately under eccentric axial loads. This eccentric loading creates an internal moment, and, in turn, increases the moment carrying capacity of the beam. They are commonly used on highway bridges.

Mathematical methods for determining the beam forces (internal forces of the beam and the forces that are imposed on the beam support) include the moment distribution method, the force or flexibility method and the direct stiffness method.

Most beams in reinforced concrete buildings have rectangular cross sections, but the most efficient cross section is a universal beam. A universal beam is only the most efficient shape in one direction of bending: up and down looking at the profile as an I. If the beam is bent side to side, it functions as an H where it is less efficient. The most efficient shape for both directions in 2D is a box (a square shell), however the most efficient shape for bending in any direction is a cylindrical shell or tube. Efficiency means that for the same cross sectional area (volume of beam per length) subjected to the same loading conditions, the beam deflects less. Other shapes, like L (angles), С (channels) or tubes, are also used in construction when there are special requirements.

Give a brief overview of the structure and contents of Text 7B.

Relate each heading to the corresponding paragraph of Text 7B.

 

a) Beam profiles.

b) Beam forces.

c) A bending moment.

 

d)Beam shapes.

e) The stresses experienced by a beam.

f) The loads carried by a beam.

g) Prestressed concrete beams.

22. Read Text 7C "Framing Construction" and answer the questions. Discuss your answers with your groupmates.

a) What sort of building technique is framing?

b) What members does wall framing include?

c) What are the common methods of framing?

d) What is post and beam framing characterized by?

e) What is specific of balloon framing?

f) What does platform framing consist in?

g) Why is a multiple stud post used at exterior corners?
h) What supports the upper floors, ceiling and roof?

i) What are loadbearing and non-loadbearing walls?

j) What are lintels constructed of?

k) When are the assembled sections nailed together?

• TEXT 7C

Framing Construction

Framing is a building technique based on structural members which provide a stable frame to which interior and exterior wall coverings are attached and covered by a roof comprising horizontal ceiling joists and sloping rafters (together forming a truss structure) or manufactured pre-fabricated roof trusses — all of which are covered by various sheathing materials to give weather resistance.

Wall framing in house construction includes the vertical and horizontal members of exterior walls and interior partitions, both of bearing walls and non-bearing walls. Studs, wall plates and lintels serve as a nailing base for all covering material and support the upper floor platforms, which provide the lateral strength along a wall. The platforms may be the boxed structure of a ceiling and

6*

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roof, or the ceiling and floor joists of the storey above. There are three historically common methods of framing a house.

—Post and beam framing is now used in barn construction.

—Balloon framing using a technique suspending floors from the walls was common until the late 1940s, but since that time platform framing has become the predominant form of house construction.

— Platform framing often forms wall sections horizontally on the
sub-floor prior to erection, easing positioning of studs and
increasing accuracy while cutting the necessary manpower. The top
and bottom plates are end-nailed to each stud with two nails. Studs
are at least doubled at openings, the jack stud being cut to receive
the lintels (headers) that are placed and end-nailed through the
outer studs.

Wall sheathing, usually a plywood or other laminate, is usually applied to the framing prior to erection, thus eliminating the need to scaffold. A multiple-stud post made up of at least three studs is generally used at exterior corners and intersections to secure a good tie between adjoining walls and to provide nailing support for the interior finish and exterior sheathing. Corners and intersections, however, must be framed with at least two studs. Nailing support

for the edges of the ceiling is required at the junction of the wall and ceiling where partitions run parallel to the ceiling joists.

A two-story wooden-frame house under construction — the location of the upper floor platform is readily discerned by the wide joists between the floors, and the upper structure rests on this platform.

Wall framing in house construction includes the vertical and horizontal members of exterior walls and interior partitions. Studs, wall plates and lintels serve as a nailing base for all covering material and support the upper floors, ceiling and roof.

Exterior wall studs are the vertical members to which the wall sheathing and cladding are attached. They are supported on a bottom plate or foundation sill and in turn support the top plate. Interior partitions supporting floor, ceiling or roof loads are called loadbearing walls; others are called non-loadbearing or simply partitions. Interior loadbearing walls are framed in the same way as exterior walls.

Lintels (headers) are the horizontal members placed over window, door and other openings to carry loads to the adjoining studs. Lintels are usually constructed of two pieces of lumber separated with spacers to the width of the studs and nailed together to form a single unit. The preferable spacer material is rigid insulation.

The complete wall sections are then raised and put in place, temporary braces added and the bottom plates nailed through the subfloor to the floor framing members. Once the assembled sections are plumbed, they are nailed together at the corners and intersections. A strip of polyethylene is often placed between the interior walls and the exterior wall, and above the first top plate of interior walls before the second top plate is applied to attain continuity of the air barrier when polyethylene is serving this function. A second top plate usually laps the first plate at the corners and partition intersections and, when nailed in place, provides an additional tie to the framed walls.

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'--- il SECTION 4
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—II LISTENING AND SPEAKING

23. Listen to the Text "A Horizontal Support".

a) Answer the questions that follow.

1. What is a beam?

2. What materials can beams be made of?

3. What forces are beams usually subjected to?

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UNIT 8

4. What conditions are reinforced beams used under?

5. What elements can beams rest on?

 

b) Check your answers with your groupmates and Tapescript 7A of the Text. Look up the words you do not know in the dictionary.

c) Retell the Text about beams.

d) Tell your groupmates about beams based on the information to be collected.

24. Listen to the Text "Roof.

a) Which of these statements are true and which are false?

1. The roof design depends on the climate of the place in which a building is located.

2. The roof of a building protects people from rain and sun.

3. Where it often rains, the roof slopes steeply.

4. It is convenient to live in a house with sloping sides.

5. Triangular frameworks are called trusses.

6. In the Middle Ages the wooden frame of the roof was hidden by a ceiling.

7. The hammer-beam roof increased the effect of height and space.

8. The waterproof covering of a pitched roof is made of thick slabs of baked clay.

9. Sheets of weatherproof roofing-felt help to keep out rains.
10. When a roof covers a large space, wood trusses are used.

b) Check your answers with your groupmates and Tapescript 7B of the Text. Look up the words you do not know in the dictionary.

c) Retell the Text about different types of roofs.

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