橋梁設(shè)計(jì)外文翻譯--荷蘭跨線高架橋-wenkub
2023-05-18 13:35:45 本頁(yè)面
【正文】 spans were determined by the remaining space between sections I and VI and costoptimisation. Section II crosses the polder drainage pool. Section VI, with a length of 167 m, crosses the two existing and the two future tracks. Thespans range between and m, with the supports staggered under the side beams. Allbridges have been made from prestressed concrete. To limit the construction height, it was decided to employ a Ushaped crosssection (fig. 2). The track floor lies low between the two loadbearing perimeter beams with a breadth of . The height of the beams is m for the small spans and m for the larger. Theappearance of a gradual transition from low to high beams is caused by walls that increase inheight at the ends of the low beams, connecting to the high beams. The track construction consists of a continuous ballast bed. Only for the transition fromsection VI to the track bed are two pensation welds used in the rails to absorb changes inlength due to temperature shifts. At the other joins between the bridge sections the rails run continuously through. The lack of space at the site means that the crossing angle with the tracks that are to be newlylaid is only 10 degrees. In addition, points are projected to be positioned in the tracks passing underneath, so that no columns can be located between the new tracks. For such situations, ‘pergola constructions’ are often built, consisting of long rows of columns along the trackwhich support a concrete deck with a span direction perpendicular to the tracks passingunderneath. The pergola would in this situation be 160 m long and vary between 14 m and 28m in width. For aesthetic and economic reasons, an innovative solution has been developed: Thesuspension of the crossing Ushaped bridge from a pylon which is constructed over the tracksthat will be running underneath (fig. 3). This creates a transparent construction thatguarantees a view of the countryside and clearly expresses the forces at work. This bridge isthe first of its kind in the Netherlands. Despite the high construction cost of the pylon, the total cost of the solution chosen is lowerthan for a pergola. The suspension from the pylon is such that the forces in the Ushaped bridge work as evenlyas possible and high peak stresses are avoided. The load from the Ushaped beams is divertedto the three suspension cable anchors per beam underneath. The cables run via conduitsthrough the beams to the intersection of the ridge beam and the slanting pylon columns (fig. 4). The horizontal loads from the bridge are fed directly to the columns of the pylon via ridgeslocated on the outside of the Ushaped beams. 4. CONSTRUCTION ASPECTS Static system superstructure The flyover is constructed from six bridge sections. The bridge
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