Ex. 3 Are these statements true or false?

1. The cost of the mechanical and electrical systems in buildings has decreased at a greater rate.

2. The growing use of power has increased the amount of wiring that must be installed in buildings.

3. The conduits are lo­cated only in the hung ceiling space.

4. Some buildings, particularly in remote locations, are equipped with their own primary electrical generating systems.

5. The usual method of carrying away waterborne waste is through piping connected to the sewer system inside the building.

Ex. 4 Answer the questions.

1. What greatest improvements in building construction are known?

2. Why may some areas in a building need to be cooled even in winter?

3. Why has the cost of the mechanical and electrical systems in buildings increased at a greater rate?

4. What are engineering systems controlled by?

5. What has increased the amount of wiring that must be installed in buildings?

6. Where do main cables run?

7. Why has the electrical power required in buildings increased?

8. Why are emergency power generators installed in an increasing number of buildings?

9. What are some buildings, particularly in remote locations, equipped with?

10. What is the major form of vertical transportation in high-rise structures?

11. What is necessary to provide in a building?

12. What is disposal of wet and dry wastes in buildings accomplished by?

13. What is new technology aimed at?

TEXT 5

Ex.1 Read the text and translate it into Russian.

STRUCTURE

The major elements of a building include the following: the foundation, which supports the building and provides stability; the structure, which supports all the imposed loads and transmits them to the foundation; the exterior walls, which may or may not be part of the primary supporting structure; the interior partitions, which also may or may not be part of the primary structure; the environmental-control systems, including the heating, ventilating, air-conditioning, lighting, and acoustical systems; the vertical transportation sys­tems, including elevators, escalators, and stairways; communications, which may include such subsystems as intercommunications, public address, and closed-circuit television, as well as the more usual telephone-wiring systems; and the power, water supply, and waste disposal systems.

The basic elements of any ordinary structure are the floors and roof (including horizontal supporting members), columns and walls (vertical members), andbrac­ing (diagonal members) or rigid connections used to give the structure stability.

With low buildings the variety of possible shapes is much greater than with taller buildings. In addition to the familiar box shape, which is also used in very tall buildings, low buildings may use cathedral-like forms, vaults, or domes. A simple single-story structure might consist of a reinforced-concrete slab laid directly on the ground, exterior masonry walls supported by theslab (or by a spread footing cast continuously around the perimeter of the building), and a roof. For low buildings, the use of interior columns between masonry load-bearing walls is still the most common construction method. Spaced columns supported by the slab or by individual spread footings may be used, how­ever; in that case the exterior walls can be supported by or hung between me col­umns. If the roof span is short, abutting planking made of wood, steel, concrete, or other material can be used to form the roof structure.

Each structural material has a particular weight-to-strength ratio, cost, and dura­bility. As a general rule, the greater the roof span, the more complicated the structure supporting the roof becomes and the narrower the range of suitable materials. De­pending on the length of the span, the roof may have one-way framing beams or two-way framing (beams supported on larger girders spanning the longest dimension). Trusses can be substituted for either method. Trusses, which can be less than 30cm (12in) or more than 9m (30ft) deep, are formed by assembling tension and compression members in various triangular patterns. They are usually made of timber or steel, but reinforced concrete may be used.

The structure of a simple one-story building may also consist of the wall and roof framing combined by being either fastened together or shaped in one piece. The possible structural shapes arc almost infinite and include the three sides of a rectangle fastened together into a unit called a bent, the familiar church form of vertical sides and sloping roof, the parabola, and the semicircle or dome.

The supporting structure and exterior walls, floor, and roof may also be made as a unified whole, much like a rectangular pipe with closed or open ends. These forms may be cast in reinforced plastic.

By far the most common form of building structure is the skeleton frame, which consists essentially of the vertical members and combined with a horizontal framing pattern. For tall buildings, the use of load-bearing walls with horizontal framing members has declined steadily; nonload-bearing curtain walls are used most frequently.

The skeleton frame most often consists of multiples of the construction. For structures up to 40 stories high, reinforced concrete, steel, or compos­ite-reinforced concrete and steel can be used in a variety of ways. The basic ele­ments of the steel skeleton frame are vertical columns, horizontal girders spanning the longer distance between columns, and beams spanning shorter distances. The frame is reinforced to prevent distortion and possible collapse because of uneven or vibratory loads. Lateral stability is provided by connecting the beams, columns, and girders; by the support given the structure by the floors and interior walls; and by diagonal bracing or rigid connections between columns, girders, and beams. Reinforced concrete can be used in a similar way, except that concrete shear walls would be used instead of diagonal bracing to provide lateral stability.

Newer techniques of constructing moderately high buildings include inserting prefabricated units within the skeleton frame; cable hanging; and stacking.

For the insertion technique, a stable skeleton frame may be constructed with a utility core that includes fire stairs, elevators, plumbing, piping, and wiring. Prefabricated boxlike units then can be inserted in the openings between the horizontal and vertical framing. Major changes in the future use of the building could then be made by removing and replacing the boxlike units.

In hanging a vertical utility core is built, and strong horizontal roof framing is anchored to the top of the core. All floors below, except at ground level, are supported by attaching them to the core and to tension members hung from the roof framing. After the core is complete, the floors are built from the top down.

Stacking is a construction technique in which prefabricated, box-like units are raised by cranes and placed on top of and alongside each other and then are fastened together.

For buildings over 40 stories, typically steel had been considered the most ap­propriate material. However, recent advances in the development of high-strength concretes have made concrete competitive with steel. Tall buildings often require more sophisticated structural solutions to resist lateral loads, such as wind, and earthquake forces. One of the more popular structural systems is the exterior struc­tural tube, which was used in the construction of the World Trade Center (411 m/1350 ft) in New York City. Here, closely spaced columns connected rigidly to the horizontal spandrel beams on the perimeter of the building provide sufficient strength to resist loads and the stiffness to minimize lateral deflections. The struc­tural tube has now been used with concrete and with composite construction con­sisting of structural steel members encased in reinforced concrete.

For very tall buildings, the mixing of steel and concrete is becoming more popular. The high strength-to-weight ratio of steel is excellent for the horizontal spanning members. High-strength concretes can economically provide the compression resistance needed for vertical members. In addition, the mass and internal damping properties of the concrete assist in minimizing vibration effects, which are potential problems in very tall buildings.