1、 - I - 外文翻译 Quick fix: replacement of an old wooden bridge in St Petersburg was completed earlier this year. Rising traffic levels and development demands led to an old tramway bridge being rebuilt as a cable-stayed crossing in the Russian city of St Petersburg. The new Lazarevsky Bridge across the
2、Malaya Nevka was opened to traffic earlier this year, replacing an old wooden structure which was built for trams but recently had only been used by pedestrians. The bridge is located in Petrograd district and connects Krestovsky and Petrogradsky Islands along Pionerskaya and Sportivnaya Streets, bo
3、th of which are importanat links for local traffic. When it was built in 1949, the crossing was called the Koltovsky Bridge, after the adjacent Malaya Nevka river embankment. But in 1952, it was renamed to commemorate the legendary Russian admiral Mikhail Lazarev. The embankment and the bridge were
4、redesignated the Admiral Lazarev Embankment and Lazarevsky Bridge respectively. Built to the design of engineer VV Blazhevich, the original bridge had 11 spans, the central one being a single-leaf drawspan. It was originally designed for trams and was the only tramway bridge in the city at that time
5、. Its total length was 141m and its width was 11m, the deck consisting of metal baulks and wooden plank flooring. The timber post piers rested on piled foundations of steel pipes. But in 2002 the tramway was closed and since then, the bridge has only been used by pedestrians. Its location meant that
6、 Lazarevsky Bridge served the western part of the city-the Petrograd districts including Krestovsky island. All the road traffic to Krestovsky island used the main Krestovsky Bridge which as a consequence was considerably overloaded. Since the Lazarevsky Bridge carried no vehicular traffic it was no
7、t considered part of the road network of the district. But plans to build a new stadium at the Seaside Victory Park on Krestovsky Island just 3km from the bridge site meant that a reliable transport connection to the rest of the city was required. The local authority decided that reconstruction of t
8、he Lazarevsky Bridge was the best way to provide this. The size of new bridge was determined based on the predicted traffic levels, taking into account the prospective development of the district. According to the forecast, the annual II average daily traffic intensity on Lazarevsky Bridge will rise
9、 to 16,000 vehicles per day by 2025. Peak loads occur during major sporting events at the stadium when the bridge will be required to help relieve the area of traffic within one hour. This traffic flow includes 4,500 to 5,000 cars, so even if the Petrovsky Bridge were to be rebuilt, the Lazarevsky B
10、ridge needed two lanes of traffic in both directions in order to do this. Taking into consideration the fact that the timber structures of the bridge had been in use for more than 55 years, if the bridge reconstruction had been restricted to the widening and strengthening of the existing superstruct
11、ure and piers, it would not have ensured the longevity of the fixed bridge and might have led to high operation costs. Another consideration was that the appearance of a multi-span structure with bulky piers would not have fitted into the architectural style that is emerging with construction of mod
12、ern buildings on Krestovsky Island and the adjacent embankments. As a result, the decision was taken to completely demolish the existing bridge and replace it with a new structure on the same alignment. As part of the project, some of Sportivnaya Street on the right bank had to be widened, and impro
13、vement of the adjacent area was also included. The history of the project dates back more than a decade to 1998, when JSC Institute Strojproect won the tender to carry out a feasibility study into the reconstruction of Lazarevsky Bridge and its approaches. Even at this time, the architect Igor Sereb
14、rennikov had developed an original architectural concept of the bridge which involved use of a cable-stayed system. This concept was approved by the citys committee for development but financial problems meant that the design was suspended for seven years before it resumed. In 2003, the project was
15、included in the target programme of design and survey works, and the tender for design development was officially announced. Again these works were awarded to JSC Institute Strojproect. The reconstruction design was completed in 2007 and was received positively by the State Expert Review Board； cons
16、truction began at the end of that year. The structural concept of the bridge was approved based on the comparison of technical and economical options. One of the main restrictions was the strict limitation on the superstructure construction depth. On the one hand, it was limited by the need to maint
17、ain III underbridge clearance for navigation, while on the other hand the deck level was governed by the height of Admiral Lazarev Embankment, which could not be raised, according to the requirements of the committee for protection of monuments. To meet these almost incompatible conditions it was ne
18、cessary to make the longitudinal profile of the deck with a vertical curve of radius 1,000m, a radius which is allowable only for very constrained conditions. But even with this minimum vertical curve radius, the limitation for the deck construction depth remained fairly strict-it had to be 1.4m at
19、the maximum. This condition could be met either by a classic five-span continuous beam scheme or by a cable-stayed system. The costs of both options are practically the same but the cable-stayed option was preferred as it was considered more attractive from the architectural point of view. Another b
20、enefit was that it would take less time for construction as there was no need for intermediate piers to be built in the river bed. The unconventional appearance of the structure, particularly the shape of the tower and its asymmetric arrangement with its single span, put demands on the design abilit
21、ies of the engineers from JSC Institute Strojproect, requiring them to cope with non-standard problems. One such problem was the need to provide the required rigidity to the deck while at the same time minimising its weight in order to decrease the moments in the tower elements and balance the syste
22、m. Hence a single-span cable-stayed bridge with steel deck, orthotropic carriageway slab and a steel tower was selected for construction. The deck is supported by two rows of stays, with five stays in each row. The cable stays pass through the tower and are anchored in the reinforced concrete slab o
23、f the counterweight which is located beyond the bridge abutment on Krestovsky Island. The front arch of the tower, which is inclined towards the riverbed, carries the dead anchorages by which means the cable stays and backstays are secured. Tensioning of both sets of cables was carried out by means
24、of active anchors located at the deck and in the counterweight slab. To minimise the total width of the deck, the anchorages are removed to the front surfaces of the main beams. The optimum force distribution in the tower elements was obtained by means of the arch shape that became sharper and elong
25、ated in the transverse section of the bridge. The deck consists of a system of longitudinal and transverse H-beams connected via the orthotropic slab with its U-shape stiffeners. The anchorages are located along the transverse beams. At the tower, the deck is rigidly fixed and at pier one it rests on Maurer spherical
