Vocabulary notes

beam балка, брус, перекладина

to bend изгибать, сгибать

to sag провисать; прогибаться

to stretch растягиваться; простираться

to compress сжимать

tensile stress растягивающее напряжение

tension напряжение; растяжение; натяжение

magnitude величина, размер; значение (цифровое)

virtue сила действия

to string подвешивать провода

to anchor закреплять

squeeze сжатие; сдавливание

to pour отливать; заливать (бет. смесь)

to relieve выпускать (газ); понижать (давление)

formwork опалубка

shear срезание, срез

EXERCISES

I. Read the text, translate it into Russian.

II. Discuss the advantages of prestressed concrete.

Prestressed beams, arch beams, slabs and shells

The prestressing of these structural systems may be achieved in two ways:

a) Pretensioning of the reinforcing before the concrete is hardened.

The steel is tensioned against exterior anchors and embedded in fresh concrete. When, after certain, curing process, the concrete is sufficiently hardened to carry the stretching forces, the steel is released from the prestressing bed, thus inducing compressive stresses in the concrete as a result of the bond between the embedded steel and concrete.

b) Pretensioning of the reinforcing after the concrete is hardened.

The prestressing wires or cables are pulled through ducts or grooves left for them in the concrete member or are surrounded by a sheath of thin sheet metal before the concrete is placed, in order to prevent bond prior to pretensioning.

When the concrete is hardened sufficiently, the wires or cables are tensioned by jacks acting against the ends of the concrete member. During the pretensioning the wires or cables are held in predetermined positions by means of special spacers. After the prestressing load is applied to the cables or wires, they are grouted in under high pressure for protection against corrosion and to establish bond.

Economic consideration. The economy of various structures for a given span and live load depends primarily on the dead load of the structure, the total coast of materials used, the man-hours required for construction, and the cost of maintenance.

Vocabulary notes

hard жесткий, твердый

to harden затвердевать

to embed вставлять; внедрять; монтировать

curing(concrete) выдерживание (бетона)

bond связь; соединение; сцепление

duct канал (для арматуры)

groove желобок; паз

jack домкрат

spacer распорка

grout раствор

EXERCISES

I. Answer the following questions:

1. What different groups of prestressed structures do you know?

2. What is the main difference between them?

3. How is the prestressing of the beams, arch beams slabs and shells achieved?

4. What are the main economic considerations of prestressing?

II. Make a brief summary of the text.

Building industry

Building is the process of constructing buildings as distinct form of the art of science of designing buildings, which is architecture.

The building industry has developed from the process of using natural materials for building simple shelters in early times to the complex industrial process of modern times. Many of the materials used today are made in factories and are often partly put together before they even reach the building site.

Large Modern Buildings. When we look at the buildings around us we may put them into two groups: large commercial, industrial, of institutional buildings, and the smaller, residential buildings in which many people live.

The large buildings of the first kind may be “high rise” buildings, which in extreme cases can be described as “skyscrapers”. There are special techniques used in building skyscrapers. Other large buildings such as factories, warehouses, schools, and hospitals also have to be built of materials that will bear heavy weights. Often it is desirable to produce spaces inside without posts or supporting walls. Arches, called trusses, are used to span the area to be left open. These may be made of wood, metal, or reinforced concrete. Concrete is a material used frequently in modern buildings, especially this kind of large commercial building. Another way to span a large space is to use a dome, which may be made of plastic or glass, as well as concrete or metal.