土木工程建筑桥梁外文翻译---欧洲桥梁研究-建筑结构(编辑修改稿)

土木工程建筑桥梁外文翻译---欧洲桥梁研究-建筑结构(编辑修改稿)内容摘要：

ne masonry arch bridges originally constructed for horse drawn traffic. This is less mon in other parts of Europe as many of these bridges were destroyed during World War 2. Concrete bridges A large stock of concrete bridges was constructed during the 1950s, 1960s and 1970s. At the time, these structures were seen as maintenance free. Europe also has a large number of posttensioned concrete bridges with steel tendon ducts preventing radar inspection. This is a particular problem in France and the UK. Steel bridges Steel bridges went out of fashion in the UK due to their need for maintenance as perceived in the 1960s and 1970s. However, they have been used for long span and rail bridges, and they are now returning to fashion for motorway widening schemes in the UK. Research activity in Europe It gives an indication certain areas of expertise and work being undertaken in Europe, but is by no means exhaustive. In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio. The example relates to the identification of voids in posttensioned concrete bridges, using digital impulse radar. Posttensioned concrete rail bridge analysis Ove Arup and Partners carried out an inspection and assessment of the superstructure of a 160 m long posttensioned, segmental railway bridge in Manchester to determine its loadcarrying capacity prior to a transfer of ownership, for use in the Metrolink light rail system.. Particular attention was paid to the integrity of its posttensioned steel elements. Physical inspection, nondestructive radar testing and other exploratory methods were used to investigate for possible weaknesses in the bridge. Since the sudden collapse of YnysyGwas Bridge in Wales, UK in 1985, there has been concern about the longterm integrity of segmental, posttensioned concrete bridges which may be prone to ‘brittle’ failure without warning. The corrosion protection of the posttensioned steel cables, where they pass through joints between the segments, has been identified as a major factor affecting the longterm durability and consequent strength of this type of bridge. The identification of voids in grouted tendon ducts at vulnerable positions is recognized as an important step in the detection of such corrosion. Description of bridge General arrangement Besses o’ th’ Barn Bridge is a 160 m long, three span, segmental, posttensioned concrete railway bridge built in 1969. The main span of 90 m crosses over both the M62 motorway and A665 Bury to Prestwick Road. Minimum headroom is m from the A665 and the M62 is cleared by approx m. The superstructure consists of a central hollow trapezoidal concrete box section m high and 4 m wide. The majority of the south and central spans are constructed using m long precast concrete trapezoidal box units, posttensioned together. This box section supports the in site concrete transverse cantilever slabs at bottom flange level, which carry the rail tracks and ballast. The center and south span sections are of posttensioned construction. These posttensioned sections have five types of prestressing: 1. Longitudinal tendons in grouted ducts within the top and bottom flanges. 2. Longitudinal internal draped tendons located alongside the webs. These are deflected at internal diaphragm positions and are encased in in site concrete. 3. Longitudinal macalloy bars in the transverse cantilever slabs in the central span . 4. Vertical macalloy bars in the 229 mm wide webs to enhance shear capacity. 5. Transverse macalloy bars through the bottom flange to support the transverse cantilever slabs. Segmental construction The precast segmental system of construction used for the south and center span sections was an alternative method proposed by the contractor. Current thinking suggests that such a form of construction can lead to ‘brittle’ failure of the entire structure without warning due to corrosion of tendons。