Учебное пособие 1894
.pdfopening angle - угол раскрыва; угол раствора trunnion – ось качания, ось поворота resembling – аналогичный
rocking chair – кресло-качалка refinementулучшение, очищение
folding bridge – складной мост, откидной мост, подъёмный мост drawbridge –подъемный, разводной
curling bridge – скручивающийся мост conceive – постигать, понимать collapse - сжимать
conceale скрывать, утаивать piston – поршень
octagonal shape – восьмиугольная форма cable – канат, трос
mountдержатель; крепление; опора, стойка; основание. benefit – преимущество, выгода, польза
restriction – ограничение vessel – судно
retractable bridge – отводной мост submersible bridge – погружной мост
tilt bridge –мостовое полотно поворачивается на концах по концам на определенный угол
swing bridge –разводной мост с подъемным механизмом, располагающимся под мостом
VII. Name the types of movable bridges
UNIT 3
TRUSS BRIDGE
I.Read the text and answer the questions.
1.What is the main difference between truss bridges and beam or girder ones?
2.What is a truss?
3.Where may the trusses be placed?
4.Why are truss bridges used for railroads and military bridges?
Truss bridges are similar to beam or girder designs but are capable of supporting heavier loads. The sides of the bridge are made from a series of triangles that form a steel web known as a truss. The trusses may be placed below the deck so that traffic rides overtop, or they may be placed on either side to allow vehicles to pass between the trusses. Truss bridges have a high strength-to-weight ratio due to their triangular structure. They are often used for railroad and military bridges because
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they are cost-effective and capable of supporting heavy loads.A truss is constructed of a simple supporting lattice-work of triangles that support the beam or the span by adding rigidity. It increases the beam's ability to dissipate the compression and tension forces. The members of a truss are the chords or horizontals, verticals and diagonals, which will only act in compression or tension.(fig. 9).
Fig. 9. Truss bridge
Piles or pilings are the vertical members of a truss bridge. They are long columns of wood or steel driven into the ground to support vertical loads. The members are pinned together at the nodes where the straight members meet. This allows for some movement of the members without snapping (fig. 10).
Fig. 10. Three-sided truss:
а) diagram б) profile
в)intermediate fixing of take-up г) end fixing of take-up;
1 - tensive elements of a string
Word list profile – сечение
intermediate fixing of take-up – промежуточное крепление натяжного устройства end fixing of take-up концевое крепление
tensive elements of a string –напрягающие элементы затяжки
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II. Try to make the text using the following questions as a plan:
1.What does lattice-work of triangles support. How does it act
2.What are the members of a truss? When do they act
3.What are piles or pilings? Why do they move without snapping
III. Find English equivalents to the expressions from the text.
строительный материал __________________________________________
базируется на простоте строительства ______________________________
податливый и упругий ___________________________________________
строительные лесоматериал _______________________________________
в форме эстакады ________________________________________________
The initial popularity of the truss bridge was based primarily on its simplicity of construction and economics of building the bridges. In the 1800s, wood was cheap and plentiful. Wood was an ideal construction material because it was flexible and elastic to some degree and could withstand the variety of forces that acted against it. The early truss bridges were built from wooden timbers and were constructed in trestle forms where they were composed of a braced framework of timbers, piles or steel beams built to carry roads or railroads over a depression in the landscape topography
IV. Find the information about Iron Bridge (G.B. Wales) in internet and describe the bridge
Fig.11 Iron bridge
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V.Translate the abstracts from English into Russian using t he word list.
Compression and Tension Forces
Compression and tension are seen in a bridge in the road deck, which shortens on top as traffic weight loads bear down directly on it. The compression on the upper side of the decking causes t he underside to go into tension and stretch. The diagonals and horizontal members of a truss transfer the forces to the pilin gs. At these points, most of the downward load or weight of compression applied to th e structure is dissipated or transferred into the earth. Dissipation means to spread the force out or transfer it to a larger area so that no one point bears the entire concen trated focus of the force (fig. 12).
Fig. 12 Arrows are forces on hinges
VI. Complete the sentences using the following words only once.
To shorten, shortening , com pression, forces, bears down, lengthens, lengthening Forces Acting on Truss Bridges
a)There are two major forces that act on bridges: _____________ and tension.
b)The compression force __ __________on an object ___________or compress it, while tension is the directly opposing force that __________and stretches the object.
c)A spring is a good example of a simple mechanism that works w ith both________.
d)Compression pushes the c oils together, thus ____________the
spring and tension pulls the coils further apart, __________the spring (fig. 13)
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Fig. 13. Arrows suggest forces acting on the structure
VII. Read the text. Name the forces which cause stress on bridges. Characterize them orally.
Other Forces Acting On Truss Bridges
Other forces, such as torsion, resonance and seismic forces from earthquakes cause stresses on bridges. Torsion is a rotational or twisting force produced during storms with high hurricane or near hurricane strength winds. Truss construction allows the winds to blow through both the substructure and the superstructure of the road deck so that torsion is minimized.
Resonance refers to standing waves that can run through a bridge causing it to fail through fatigue. Fatigue refers to the repeated bending up and down of horizontal members causing them to fail. A simple example when an army marches across a bridge, the soldiers are ordered to "break step" so that the cadence is broken and wave forms cannot set up. The simple truss construction disperses forces through the members so that no single member can be overstressed in this manner.
Seismic waves caused by earthquakes move through the ground and perturb the surface in all three dimensions. Waves move back and forth, up and down and from side to side and it's very difficult for any structure to resist this kind of punishment.
Truss bridges are just as vulnerable as any other structure to this kind of failure. Railroads have replaced almost all truss bridges in areas prone to seismic disturbance (fig.14)
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.
Fig. 14. Other forces acting on truss bridges
Word List
strength-to-weight ratio - отношение предела прочности к массе cost-effective – доходный, прибыльный, рентабельный lattice-work – решетчатая ферма
rigidityжесткость, твердость
to dissipate – рассеивать, разгонять tension forces - сила [усилие] натяжения tension – напряженное состояние pilings – забивка свай
pin – прикреплять node – узел
snap - защёлка; (клепальная) обжимка; зажим
intermediate fixing – промежуточная закрепление (фиксация) take-up – натяжное приспособление
construction material - строительный материал simplicity of construction простоте строительства flexible - податливый
elastic - упругий
trestle forms - в форме эстакады
a braced framework of timbersжесткая деревянная рамная конструкция to carry roads or railroadsподдержание автодорожного или железнодорожного полотна plentiful - изобилующий, изобильный, обильный
depression - оседание, понижение; углубление 3) выбоина (дороги) ; впадина,
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UNIT 4
PREFABRICATED STEEL BRIDGE SYSTEMS
I. Read the text. Choose from the list A-E the headlines which best suit each part of the text that follows. There is an extra headline which you do not need to use.
A – Emergency bridge B – Temporary bridge C - Permanent bridge D -Beam bridge
С - Prefabricated Steel Bridge
Title: _____________________________________
1. prefabricated steel bridges are utilized to divert traffic during bridge repair, rehabilitation, construction, or replacement. These bridges are installed as a temporary structure during construction and then disassembled and stored until used again as a temporary structure. (fig. 15).
Fig. 15
2.Title:_______________________________________________
…bridges also are needed from a security standpoint, and due to man-made nonterrorist hazards like ship impact, truck impact, fire, and blast. Natural disasters such as hurricanes, mudslides, fires, and tornados can destroy a bridge by washout or collapse. Typical prefabricated bridges can be erected much faster than the time of constructing a cast-in-place structure. Moreover, with the increased threat to our nation's infrastructure due to terrorism, these systems could be utilized in a time of national emergency. (fig. 16).
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Fig. 16
Title________________________________________________
It was built as the third permanent bridge across the Neva between 1897 and 1903 by the French firm "Batignolles". It is 582 meters long and 23.6 meters wide.
Former names of the bridge are Equality Bridge (Russian: мост Равенства, 19181934), and Kirovsky Bridge(fig. 17).
Fig. 17
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4 Title___________________________________
:.… structure requires a design service life of 75 years. A major objective of this study is to provide recommendations that will increase the use of prefabricated steel bridges as permanent bridges. The systems in use today have evolved greatly from the original designs conceived over 60 years ago. Today, the designs are longer, wider, stronger, and more durable. Allowance for the rapid replacement of decks or entire superstructures makes the prefabricated bridge industry an attractive option. Also, as they gain widespread acceptance and use, mass production of the systems will make them more economical.
I.Are the sentences True or false? Correct those which are wrong.
T/F
A permanent structure are utilized to divert traffic during bridge repair, rehabilitation, construction, or replacement
Typical prefabricated bridges can be erected much faster than the time of constructing a cast-in-place structure
The systems in use today have evolved over75 years.
The temporary bridges are installed much faster than the time of constructing a cast-in-place structure.
II. Find English equivalents in the text, using the word list in the unit. привлечение заводского производства ________________________________
обеспечение комплектующими _______________________________________
изготовленные на заводе (готовые) ___________________________________
массовое производство _____________________________________________
временные затраты на строительство __________________________________
экономическая выгода ______________________________________________
проектировщики – новаторы _______________________________________
изготовление цельных сборных конструкций пролетных строений сборные составные блоки __________________________________________
содержание транспортного контроля __________________________________
плиты настила (ездовым полотном) __________________________________
стройплощадка ___________________________________________________
возведенные на месте ______________________________________________
полоса отвода моста _______________________________________________
управление проектами ______________________________________________
время строительства на площадке _____________________________________
обходные пути _____________________________________________________
перевозка товаров __________________________________________________
The involvement of the prefabrication industry in steel bridge construction is primarily in providing components that are prefabricated in a factory. Through mass
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production and reduction of on-site construction time, economical benefits are most often achieved.
Innovative bridge designers and builders are finding ways to prefabricate entire segments of the superstructure. Prefabricated composite units include steel elements prefabricated with a composite deck, transported to the project site, and then erected in place. Prefabricated systems could also be constructed in the right-of-way along side of the bridge and then lifted into place. Such prefabrication offers advantages of easier constructability, reduced on-site construction time and therefore reduced maintenance of traffic control and detours to the traveling public and transportation of goods.
IV.Translate the text from ex. I about the permanent bridges from English into Russian in written form.
V.Name the main peculiarities which differ one bridge described in the text from another. Do it orally.
Word List
allowance - денежное содержание, учёт; допуск, поправка (при измерении) benefit – выгода, прибыль
blast – сильный порыв ветра
collapse - продольный изгиб; сплющивание; разрушение , потеря устойчивости components - комплектующие
composite - составной conceive – постигать, понимать
constructability - управление проектами - detours - обходные пути, объезд disassemble - демонтировать, разбирать
divert – отводить, отклонять; изменять маршрут durable – надежный, прочный
emergency bridge – вспомогательный (аварийный ) мост entire – целый, полный
erectустанавливать, возводить goods товаров
hazards - опасность, риск; опасное положение hurricanes - ураган
installустанавливать maintenance содержание
mass production - массовое производство mudslides - оползень
permanent bridge – постоянный (высоководный) мост prefabricate – изготавливать заводским способом project site - стройплощадка
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