Design and Construction of a double-curved railway overpass and 3-track tubular arch

摘要

The new railway connection between Brussels Airport and the North of Belgium is being built inrnthe available space of the central reservation in between both driving directions of the E 19rnmotorway from Brussels to Antwerp. Among other important structures, this new line alsorncomprises two particular steel bridges. Both have been especially designed for the particularrngeometry of each crossing and according to the requirements for erection.rnThe overpass at Zemst allows the new railway to cross one driving direction of the motorway, asrnthe tracks change location from the central reservation towards the town of Mechelen. Hence, it isrncompletely located in a curved track alignment and constitutes a skew crossing. Due to theserncharacteristics, a continuous closed-section steel structure with 2 lateral edge members, including arncurved cross-section was designed. The central span is supported by 2 single bearings, thusrnrequiring all torsion to be resisted by the double bearings at both ends of the steel structure. Inrnaddition, the live loads being able to introduce lifting reactions at both ends, the hollow parts of thernstructure had to be ballasted by a concrete filling near both ends. The typical cross-section of thernbridge was mainly inspired by the torsion moments appearing in the steel girder. The superstructure,rnwelded from workshop prefabricated parts was welded near the building site and subsequently putrnin place by using movable hydraulic jacks.rnThe bridge across the Woluwe Lane carries 3 tracks, the two lateral ones being located above twornmain steel tube arches, whereas the central track is supported by a composite bridge deck, hangingrnbelow these arches. The connection between each bridge deck and the steel arches consists ofrnalmost vertical tube struts. During design, particular care has been given to the node detailing in thisrntubular bridge. In addition, the Woluwe Lane is an integral bridge, having no bearings or joints.rnDuring construction, lateral buckling of the arches had to be prevented by temporary lateralrnsupports. Erection of the tubular arches, particularly in assuring correct thrust forces in the mainrnarches, has required increased effort during construction.