Arches and their types

An arch is a structure that spans a space and supports structure and weight above it. Arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture and their systematic use started with the Ancient Romans who were the first to apply the technique to a wide range of structures.

The most common true arch configurations are the fixed arch, the two-hinged arch, and the three-hinged arch.

The fixed arch is most often used in reinforced concrete bridge and tunnel construction, where the spans are short. Because it is subject to additional internal stress caused by thermal expansion and contraction, this type of arch is considered to be statically indeterminate.

The two-hinged arch is most often used to bridge long spans. This type of arch has pinned connections at the base. Unlike the fixed arch, the pinned base is able to rotate, allowing the structure to move freely and compensate for the thermal expansion and contraction caused by changes in outdoor temperature. Because the structure is pinned between the two base connections, which can result in additional stresses, the two-hinged arch is also statically indeterminate, although not to the degree of the fixed arch.

The three-hinged arch is not only hinged at its base, like the two-hinged arch, but at the mid-span as well. The additional connection at the mid-span allows the three-hinged arch to move in two opposite directions, and compensate for any expansion and contraction. This type of arch is thus not subject to additional stress caused by thermal change. The three-hinged arch is therefore said to be statically determinate. It is most often used for medium-span structures, such as large building roofs. Another advantage of the three-hinged arch is that the pinned bases are more easily developed than fixed ones, allowing for shallow, bearing-type foundations in medium-span structures. In the three-hinged arch, thermal expansion and contraction of the arch will cause vertical movements at the peak pin joint but will have no appreciable effect on the bases, further simplifying the foundation design.

Arches have many forms, but all fall into three basic categories: circular, pointed, and parabolic. Arches can also be configured to produce vaults and arcades.

Arches with a circular form, also referred to as a rounded arch, were commonly employed by the builders of ancient history. Ancient Roman builders relied heavily on the rounded arch to span large, open areas. Several rounded arches placed in-line, end-to-end, form an arcade, such as the Roman aqueduct.

Pointed arches were most often used by builders of Gothic-style architecture. The advantage to using a pointed arch, rather than a circular arch, is that the arch action in a pointed arch produces less thrust at the base. This innovation allowed for taller and more closely spaced openings, typical of Gothic architecture. (2700)

Тема 5.  Работа. Деловая переписка. (Work and formal correspondence)

I. Pronounce the following words and word combinations, try to memorize them:

CV (curriculum vitae)	[kəˈrɪk.jʊ.ləm vitai]	резюме, краткая биография
earn	[ɜːn ]	зарабатывать
full-time job	[fʊl taɪm dʒɒb]	работа на полный рабочий день
occupation	[ɒk.jʊˈpeɪ.ʃən]	профессия, род занятий
part-time job	[pɑːt taɪm dʒɒb]	работа на неполный рабочий день
retire	[rɪˈtaɪə(r)]	оставлять должность
salary	[ˈsæləri]	заработная плата за месяц
wage	[weɪdʒ]	заработная плата за день, неделю

II. Match the jobs with the definitions

architect bricklayer carpenter painter erector foreman joiner plumber shop-hand

1. someone whose job is making and repairing wooden objects 2. someone whose job is to build walls, buildings with bricks 3. someone whose job is to repair water pipes, baths, sinks 4. someone whose job is to design buildings 5. a skilled worker who is in charge of a group of builders at the construction site 6. someone who makes wooden doors, window frames 7. a worker at the construction site 8. someone who builds or repairs houses or other things 9. someone whose job is painting houses, walls, roofs

III. Match the questions with the possible answers. There are two answers for each question.

1. What are you going to do when you graduate from the university? 2. Why did you choose that? 3. What job would you never want to do? 4. Why?

a) I’d hate to be a plumber. b) I want to be an architect. c) Because I love designing structures. d) I could never be a writer. e) Because I don’t like working alone. f) I’m not sure yet, but maybe a foreman. g) Because I am responsible and would like to be in charge of group of builders at the construction site. h) Because I am not good at fixing and repairing things.

IV. Work with a partner. Ask him or her questions from Exercise IV then change over.

V. Match the beginnings and endings of the sentences.

1.​ Matt does things quickly and always really well. 2.​ Ted has lots of ideas. 3.​ Irene doesn’t need other people to help her. 4.​ Holly has a lot of training and experience. 5.​ Ralph does the things he has got to do. 6.​ Mary has suitable knowledge, experience and qualifications for her job.

a)​ She is very independent. b)​ He is very responsible. c)​ She is qualified. d)​ He is really efficient. e)​ He is very imaginative. f)​ She is a skilled person.