Structural elements. 1. What types of arches do you know.

Warming-up

1. What types of arches do you know?

2. What building materials were used for the construction of arches?

Read the text and say about the early forms of arches and the later development.

ARCHES

Throughout most of architectural history, the arch has been the chief means of overcoming the spanning limitations of single blocks of stone oi lengths of timber.

There were three types of arches in ancient architecture. One, which survives today in Mycenean cyclopean construction, consisted of only three rough blocks of stone, the central one somewhat larger than the gap between the other two and wedged between them. A second, of.which monumental examples survive in Egypt from the 3^rd millennium ВС, consisted of only two long blocks inclined toward one another as an inverted V-shape. This form was probably constructed even earlier in timber. The third, of which surviving examples are very widespread, was what is commonly known as the false or corbelled arch.

None of these early forms was very efficient. Spans rarely exceeded 6 ft. 6 in. (2 m). The spanning of substantially wider gaps called for true arches constructed on centering from large number of bricks or stone voussoirs. Small true brick arches appeared first in Mesopotamia and Egypt.

From the first century AD the Romans began to use concrete in place of cut stone for all the longer spans.

Later brick and stone arches departed from Roman precedents mainly in adoption of other profiles. Of these, the most important were the pointed profiles of most Islamic and of Gothic arches. The Islamic form appeared first and was preceded by a Sassanian form of roughly parabolic profile. The chief merit of the pointed profile was probably the ease with which it could be used in ribbed vaults of any plan shape and, without aesthetic inconsistency, throughout structures that vaulted in this way.

Early cast-iron arches of the late 18^th and early 19^Ih centuries all closely resembled braced timber arches. Later steel and reinforced-concrete arches have usually been given the necessary stiffness simply by the adoption of an I-shaped, boxlike, or tubular cross section.

Vocabulary

rough — грубый

somewhat — отчасти, до некоторой степени

gap — промежуток

to wedge — закреплять клином

inclined — наклонный

inverted — перевернутый

span — расстояние (между опорами арки свода)

to exceed — превышать

voussoir — клинчатый камень

to depart — отступать

inconsistency — несовместимость, несообразность

merit — достоинство

braced — укрепленный

stiffness — жесткость

tubular — трубчатый

/. Circle a), b), or с) to complete the sentences.

1. The spanning of substantially wider gaps... true arches constructed

on centering from large number of bricks.

a) received b) called for c) exceeded

2. From the first century AD the Romans began... concrete in place

of cut stone for all the longer spans.

a) to bring b) to erect c) to use

3. The chief merit of the pointed profile... the ease with which it could

be used in ribbed vaults of any plan shape.

a) proved b) was c) resembled

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