Translate the following information into English using the terminology list.

В сложных геологических условиях, когда прочные грунты залегают на большой глубине, применяют фундаменты глубокого заложения. Данные фундаменты разделяются на следующие типы:

1. Свайные фундаменты, состоящие из свай (т.е. железобетонных элементов небольшого сечения 0,35х0,35 м, и значительной длины до 12-16 м) и ростверка, железобетонного элемента, объединяющего сваи (fig. 13.1e).

2. Фундаменты на сваях-оболочках отличающиеся от обычных свай тем, что являются пустотелыми цилиндрами диаметром до 3,0 м, и длиной до 30 м.

3. Фундаменты на буровых сваях, отличающиеся от свай-оболочек только способом погружения свай.

4. Опускные колодцы, представляющие собой железобетонную коробку, которая погружается до расчетной глубины (fig. 13.1f).

5. Кессонные фундаменты отличаются от опускных колодцев тем, что работа в них ведется под давлением сжатого воздуха, чтобы оттеснить воду из кессона. Данный способ сооружения фундаментов очень опасен для здоровья рабочих из-за перепада давления воздуха в атмосфере и в кессоне (fig. 13.1g).

В настоящее время не существует геологических и гидрологических условий, препятствующих возведению фундамента глубокого заложения, так как современные механизмы и технологии сооружения фундаментов и опор достигли высокого уровня.

The Terminology List

1. Arched falsework	a) опалубочные кружала
2. Casing	b) обсадная труба, опалубка
3. Concrete setting	c) усадка бетона, схватывание бетона
4. Deep foundations	d) фундамент глубокого заложения
5. Drilled pier, boring pile	e) буровая свая
6. Grillage	f) ростверк
7. Grouting mortar	g) тампонажный раствор
8. Hollow shaft	h) пустотелый цилиндр
9. Hollow-shell pile, encased pile	i) свая-оболочка
10. In situ concrete pile	j) набивная бетонная свая
11. Pile driver	k) свайный копер
12. Ram with concrete	l) бетонировать трамбованным бетоном
13. Shallow foundations	m) фундамент мелкого заложения
14. Sheet piling	n) шпунтовое ограждение/стенка
15. Shrinkage crack	o) усадочная трещина

Think of the answers to these questions. Give a reason to support what you say.

1. What loads do bridges carry?

2. In most cases, piers are built of concrete and reinforced concrete, aren’t they?

3. According to building methods, concrete piers may be subdivided into three groups. What are they?

4. What is the difference between monolithic and precast concrete piers? What do they have in common?

5. What do the building methods for bridge foundations depend on?

6. What construction technology is suitable for foundations on solid rock?

7. Why is the sheet piling built?

8. What sorts of operations are carried out for building a pier in a river?

9. What method is used to consolidate soil in the water?

10. What building materials are used for holding vertical piles in place?

Unit 14

SUPERSTRUCTURE ERECTION

Read the text and pay attention to the differences in the various techniques of superstructure erection.

The erection technique of a superstructure depends on the span type, its dimensions and material. The span length for motorway bridges usually varies between 6 and 42 m. In the case of railway bridges the spans may be up to 34.2 m long. For short spans the choice of bridge types is very wide even for heavy loadings. For medium spans, the choice is still wide enough, but for long spans, the choice is restricted to continuous lattice girder, cantilever lattice and steel lattice bridges. When the spans are in excess of 457.2 m, the stiffened suspension bridge is the only suitable form. The following erection techniques have been developed for building different bridge structures – simple setting of discontinuous beams; erection by protrusion; launch and balanced cantilever erection.

The simplest erection technique is used for single beam spans (fig. 14.1a). Standard reinforced concrete beams are produced by casting yards, shipped to the site, and set in place by cranes (fig. 14.1a). For short spans, steel beams are usually formed as a single unit. At the site, they are placed parallel to each other, with temporary forms between them so that a concrete deck can be cast on top. The beams usually have metal pieces welded on their top flanges, around which the concrete is poured. These pieces provide a connection between beams and slabs, thus producing a composite structure.

When a bridge is designed as a continuous one the builders put simple beams on two supports, which join them into a continuous beam. For longer spans, steel beams are made in the form of plate girders. A plate girder is an I-beam consisting of separate top and bottom flanges welded or bolted to a vertical web. While beams for short spans are usually of a constant depth, beams for longer spans are often deeper at the supports and shallower at mid-span. They are called haunched beams. Haunching stiffens the beam at the supports, thereby reducing bending at mid-span. In general, shorter spans are built with beams, hollow boxes (box girders), trusses and arches, while longer spans use cantilever, cable-stay, and suspension forms.

The next, span erection method is erection by protrusion. This method is used to construct very long bridge spans by employing reinforced concrete continuous girders, which are cast on the bank and then set to the place by pushing (fig. 14.1b). While being pushed, the girder works as a cantilever resisting the dead weight. As reinforced concrete has rather high density builders use a launching nose to reduce bending in the girder (fig. 14.1b). This technique has its disadvantages, which clearly limit its use: the concrete has to be prestressed in advance, and it needs time to reach a certain density.

Framed suspended bridges, framed flyovers and trestle bridges may be constructed by two methods. The first one uses the sliding formwork for building up the span with concrete (fig. 14.1c). It results in a monolithic structure. The next method represents a balanced cantilever erection of framed structures, from ready-made reinforced concrete units produced by the casting yards (fig. 14.1d).

This method is used for prestressed concrete bridges using a concrete cantilever in short segments. The previous segment, thus avoiding the need for falsework, while it is being cast, supports each new segment. The units are stuck together with an adhesive or cement. This construction method leaves no possibility for later correction, and the elements must be fixed exactly in the right position. For steel cantilever bridges, the steel frame is built out from the towers toward the centre and the abutments. When a shorter central span is required, it is usually floated out and raised into place. The deck is added last.

The most complicated construction technology is employed for arch bridges. The traditional method demands temporary piers and centering to reproduce the shape of the arch superstructure (fig. 14.2a). The precast reinforced concrete blocks are placed on an arch centering. The monolithic concrete arch is erected in a curved framework. The construction of arches afloat is a much more advanced technique (fig. 14.2b). The arches and semi-arches are assembled on the bank and transported to a barge, which carries these structures to the place.

One of the oldest engineering forms is the suspension bridge, which is constructed by mounting the roadway directly on the continuous steel cables. Cables are generally made of thousands of high-strength steel wires spun together, at the construction site. Spinning is done by rope pulleys that carry each wire across the top of the towers to the opposite anchorage and back. A traveling wheel carries the continuous cable strand from the anchorage on one side to the anchorage on the other side, where a crew receives the wheel, anchor the strand, and return the wheel, laying a fresh strand. The wires are bundled and from these successive parallel strands, a cable is built up and covered to prevent corrosion. When the cables are complete, suspenders are hung, and finally the deck is constructed – usually by floating deck sections out on ships, hoisting them with cranes, and securing them to the suspenders.

Construction of cable-stayed bridges usually follows the cantilever method. After the tower is built, one cable and a section of the deck are constructed in each direction. Each section of the deck is prestressed before continuing. The process is repeated until the deck sections meet in the middle, where they are connected. The ends are anchored at the abutments.

Exercises:

Find the relevant information in the texts to answer these questions.

1. What does the erection technique of a bridge superstructure depend on?

2. Which erection techniques are used for suspension spans?

3. What erection technique is employed for single beam spans?

4. Where are standard reinforced concrete beams produced?

5. Which erection technique is used for long continuous bridge spans?

6. Why do beams have metal pieces welded on their top flanges?

7. What is a plate girder?

8. What is a launching nose?

9. What are the disadvantages of erection by the protrusion method?

10. Do arch bridges need the most complicated construction technology?

Complete and translate the following sentences:

Usually metal spans are erected from (типовые балки) or (типовые решетчатые фермы). The length of a standard girder is 55 m, and of a unified lattice truss it is between 33 and 132 m. Both structures may be (разрезные или неразрезные) ones. (Металлические балки) are lighter than those made of reinforced concrete, so they may be mounted by one or two (кран). When a girder is 55 m long, it is cut into four blocks to facilitate its delivery to the (строительная площадка). A temporary pier is specially built in the middle of the span. These blocks are placed by cranes on (временная опора и постоянная опора) (fig. 14.1a). They (соединяться) by high strength bolts (earlier the builders drove rivets).

Standard trusses are mounted of separate elements: top and bottom chords of a truss (раскосы, подвески, стойки, диагональные связи). A part of the span can be mounted on temporary piers built under the (узлы фермы). Three or four segments are used as a (противовес) for further span erection. A (деррик-кран) moves along the mounted top chord using the cantilevering method. The truss joint elements are jointed by (болты, фасонки, накладки) and other flat elements. Continuous metal girders may be erected as well as reinforced concrete beams by pushing them towards the designed position with a (домкрат).

The erection of a bridge superstructure afloat is one building technique. The superstructure’s blocks which are mounted at the plant site and delivered to the riverbank, by special heavy trucks, are transhipped to the (баржа). This operation is carried out with special equipment, and a barge carries the structures to the place.

Describe superstructure erection methods. Remember the following word combinations:

1. Built up concreting	a) навесное бетонирование
2. Built-up girder	b) составная балка
3. Cantilever erection	c) навесной монтаж пролета моста
4. Diagonal rod	d) раскос фермы
5. Diagonal brace	e) диагональные связи
6. Erection by protrusion	f) метод продольной надвижки пролета
7. False work	g) подмости
8. Float-on method	h) сборка на плаву
9. Gusset	i) фасонка
10. Haunched beam	j) балка с вутами
11. Launching girder (false nose)	k) аванбек, ферма для надвижки пролета
12. Panel point	l) узел фермы
13. Patch plate	m) накладка
14. Rope pulley	n) канатный шкив
15. Single beam	o) однопролетная балка
16. Standard girder	p) типовая балка
17. Tie	q) стойка решетки фермы
18. Vertical web	r) вертикальная стенка балки

Unit 15

BRIDGE MAINTENANCE

Read the text and make a list of the main ideas you should remember as a future bridge designer

The moment the bridge has been built is a celebratory occasion. The official who puts the structure into operation follows the celebration. The State Acceptance Committee is charged with the bridge availability status. Experts in the commission study all the documents and provide an on-site review and visual inspection of the bridge components. They examine them with geodetic devices to locate defects before they turn into a serious problem. The bridge is tested under static (fig. 15.1a) and dynamic (fig. 15.1b) overloading at every structural element. The welding and joints, which can change their initial position under an emergency load, are carefully examined. If the structure meets the standard requirements and the acceptance documents are signed, the bridge is transferred to the possession of the Railway and Motorway subdivisions.

The rules and demands for scheduled and emergency maintenance of R&M ES must be observed according to “Building Specifications” and provide safe operation during their service life of 80-100 years. A bridge supervisor performs all necessary engineering supervision and thorough inspection of long bridges. Short bridges and culverts are inspected by a maintenance supervisor. He or she heads a maintenance crew, which locates and fixes small damage and defects; cleans snow, slush and mud; determinates wear and deterioration of bridge components; fills in the forms and keeps detailed and accurate records of bridge inspections and testing. They also keep a written record of wear-out failures, which need general overhaul.

There are four assessment stages of a bridge condition: from zero to the third stage. The structure zero stage is its standard condition. The next stage means minor failures and damage, which can be repaired during maintenance or general overhaul. The third stage calls for reconstruction or complete replacement.

The Trans-Siberian Railway runs through permafrost areas, and bridges along this main trunk line require costly upkeep. As a lot of ice melts each summer constant maintenance includes track leveling on railroad bridges. In winter, extensive maintenance is also required to combat frost heaving when local displacements of 2.5 to 35 cm occur in roadbeds and bridges.

Bridge maintenance depends on the structure’s carrying capacity. Many R&M ES in Russia were built according to “Building Specifications” issued between 1884 and 1985. Currently the experts evaluate bridges according to superstructure and live load classification, and Building Regulations issued in 1985. When they compare bridge conditions, they draw conclusions about the operational efficiency under a modern live load.

Exercises:

Find the answers to these questions in the text.

1. What are the responsibilities of the State Acceptance Committee?

2. Why is it necessary to examine every structure?

3. When may the bridge be transferred to the railway subdivision?

4. Who performs the engineering supervision and inspection of long bridges?

5. What are the functions of a maintenance crew?

6. How many assessment stages can be defined in bridge conditions?

7. Why is constant bridge maintenance at the Trans-Siberian Railway required?

Complete the following sentences:

1. Bridge inspection involves ………………………………………

1. the inspection of bridge components and joints;

2. the verification of technical documentation;

3. the determination of forces in bridge elements.

1. The damage and defects of long bridges under operation are discovered by …

   1. the State Acceptance Committee

   2. a bridge supervisor

   3. a maintenance supervisor.

2. If a bridge is erected according to the Building Specifications issued in 1907..…………………………………………………………………………..

   1. this bridge can carry modern rolling stock.

   2. it is necessary to determine the bridge carrying capacity.

   3. it cannot provide safe passage for modern rolling stock.

Match the equivalents:

1. Availability status	a) подразделение
2. Building Specifications	b) ремонтная бригада
3. Engineering supervision	c) состояние готовности
4. General overhaul	d) земляное полотно
5. Frost heaving	e) контроль, проверка
6. Maintenance supervisor	f) разрушение вследствие износа
7. Maintenance crew	g) содержание, ремонт
8. Supervisor	h) текущее обслуживание, ремонт
9. Prove-out	i) строительные нормы
10. Roadbed	j) капитальный ремонт
11. Running service	k) пучение грунта при замерзании
12. Subdivision	l) технический надзор
13. Upkeep	m) мастер, смотритель
14. Wear-out failure	n) обходчик, дорожный мастер