Read the text and make up a bridgework glossary in Russian
Humankind has been constructing bridges since ancient times. The early human felled trees and put stones for crossing rivers or gullies, and the earliest bridges were probably nothing more than different rocks or logs thrown across the gap. As civilization advanced, people discovered ways to use a mixture of lime with cement, sand and water for binding stones by mortar to construct longer and stronger bridges. Bridge builders gained skills and experience in incorporating other natural and fabricated materials such as iron, steel, and aluminum into the structures they built.
Currently, bridge engineers define a bridge as a raised structure made out of wood, stone, brick, concrete or steel that links two opposite sides without making contact with the roadway, body of water, depression or any other obstacle beneath it. The bridge types include beam, cantilever, arch, and suspension structures according to the gap they span and the loads they have to carry. Their classification is according to the following criteria:
Criterion Number 1. (The primary function of the bridge roadway)
1.1 Railway bridges (trains).
1.2 Motorway (highway) bridges (vehicles, trucks, cars).
1.3 Footbridges (pedestrian bridges) (pedestrians, bicycles).
1.4 Town bridges (city trains, monorail, transit guideway).
1.5 Pipe lines.
1.6 Metro bridges.
1.7 Combined or road-cum-rail bridges (for different modes of transport).
Criterion Number 2. (The superstructure material) (fig.3.1)
2.1 Timber (wooden) bridges (fig. 3.1a) (logs, squared beam, plywood).
2.2 Masonry bridges (fig. 3.1b) (brick, rock).
2.3 Reinforced-concrete bridges (fig. 3.1c) (precast, cast-in-place, pretensioned, prestressed concrete, posttensioned).
2.4 Metal bridges (fig. 3.1d) (cast iron, steel, aluminum, bolted, welded, prefabricated, riveted).
2.5 Steel reinforced concrete bridges (composite bridges).
2.6 Suspension bridges (fig. 3.1e; 3.2a).
2.7 Cable-stayed bridges (fig. 3.1f; 3.2b).
|a – Timber Bridge||b – Masonry Bridge|
|c – Reinforced Bridge||d – Steel Bridge|
|e – Suspension Bridge||f – Cable-stayed Bridge|
Figure 3.1 Bridge classification by the superstructure material
Out of the main materials used in bridge building – wood, stone, steel and concrete, steel has had the greatest impact on modern bridge engineering. Bridge builders prefer exclusively reinforced and prestressed concrete, which contain steel bars or mesh. Suspension and cable-stayed bridges which use flexible ropes or cables as the main supporting element can also be regarded as representatives of metal bridges because their cables are made out of steel wire strands. Curved cables are used for suspension bridges (fig. 3.2a), and straight diagonal cables carry the main span in cable-stayed structures (fig. 3.2b).
Figure 3.2 Bridge classification
a – Suspension bridge (висячий мост); b – Cable-stayed bridge (вантовый мост);
c – Beam bridge (балочный мост); d – Arch bridge (арочный мост);
e – Rigid frame bridge (рамный мост); f – Beam-cantilever bridge (балочно-консольный мост); g – Combined half-through bridge (комбинированный мост с ездой посередине);
h – Through lattice bridge (сквозная ферма с ездой понизу); i – Drawbridge (разводной мост);
j – Pontoon bridge (понтонный мост)
Criterion Number 3. (The structural system)
3.1 Beam bridges (fig. 3.2c), (a freely supported slab or girder construction resting on piers).
3.2 Arch bridges (fig. 2d), (a curved structure producing a horizontal thrust through impost to piers). Arched spans give the bridge enhanced rigidity and strength.
3.3 Rigid frame bridges (fig. 3.2e) (a rigid frame structure with the horizontal deck slab made monolithic with the vertical abutment walls).
3.4 Cantilever bridges (fig. 3.2f) (a structure with projecting cantilever arms).
3.5 Combined systems (fig. 3.2g) (several simple structures: beam and arch).
3.6 Truss (lattice structure) (fig. 3.2h)
|a – Deck Bridge||b – Through Bridge|
|c – Half-through Bridge||d – Pontoon Bridge|
Figure 3.3 Bridge Classification according to Position of Traffic
Criterion Number 4. (Cross section or the position of traffic)
4.1 Deck bridges (fig. 3.2c, d and e; 3.3a).Their structural components are under the deck, so deck bridges need space beneath. This bridge type is the best for driversas they can clearly see the surroundings.
4.2 Through bridges (fig. 3.2h; 3.3b). Their structural components obstruct the view because they are above the deck. This bridge type is suitable for railway bridges.
4.3 Half-through bridges (fig. 3.2g; 3.3c).
Criterion Number 5. (The span length)
5.1 Short bridges (6 – 25 m).A span, which is less than 6 m, is a culvert.
5.2 Intermediate span bridges (25 – 100 m).
5.3 Long span bridges (more than 100 m).
Criterion Number 6. (The number of spans)
6.1 Single-span bridges.
6.2 Double-span bridges.
6.3 Three-span bridges.
6.4 Multi-span bridges.
Criterion Number 7. (Bridge service life)
7.1 Permanent bridges (80 – 100 years).
7.2 Temporary bridges (about 10 – 15 years).
7.3 Short-term bridges (For two/three days or for a year).
Next to the above-mentioned bridge types there are movable bridges (fig. 3.2i) (drawbridges, leaf bridges, opening bridges, pivot bridges), floating bridges (raft bridges) (fig. 3.2j; 3.3d) and ferries. The drawbridge, or bascule, is the best known; it may be single or double-leaf. For exceptionally long spans, the pivot, or swing bridge, which revolves around a vertical axis on a pivot pier, is suitable, but it limits navigation. In practice, the basic forms can take turns in one structure. The principle factors determining bridge choice include span, location and site conditions, availability of materials and labour, maintenance, loading conditions, appearance and cost.
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