【文章內(nèi)容簡介】 or the abutments was made necessary by the settlement of the connecting raised trackbeds as a result of the pressible subsoil which might subject the piles to bending. Prestressedconcrete driven piles turned out not to be able to absorb these bending moments. The columns under the Ushaped bridge ends are coupled crossways with a beam constructiondue to the horizontal forces that are diverted there via the guiding constructions. In order to be able to quantify the interaction of the track with the substructure, a tracklongitudinal forces program has been developed in which the whole system is divided intodiscrete ponents by means of the following elements: rail elements。 ballast elements。 bridge elements。 bearing elements。 pile elements。 foundation elements. The bridge system is physically described with these elements, and the acpanyingparameters are entered for each type. Generally, CWR track is used. If, however, the expanding bridge lengths bee too great, ‘pensation’ welds or pensation constructions, in which the track has overlapping ‘tongues’ and so is free to undergo deformation, must be used due to the rail forces reachingtoo high a level as a result of braking forces and temperature effects. At the location of one of the intermediate supports, bridge section VI is suspended from apylon construction where the bridge is also fixed horizontally. Due to the high stiffness of thisconstruction, this determines the free expansion length to the abutment. This length is greaterthan 60 m, the maximum free expansion length to an abutment for ballasted track. For thisreason two pensation welds are used at the abutment. Prestressing The Ushaped bridges are constructed from prestressed concrete. The following can be distinguished: longitudinal prestressing in the Ushaped beams, through which the beam’s ownweight, the permanent load and the working load are diverted。 cross prestressing of the Ushaped ends in the base. This absorbs the shear tensionsthat are generated as a result of the longitudinal prestressing. For the 167 m long trackcrossing section VI, a 27strand longitudinal prestressing systemwas chosen with strands 216。 15,2 mm, FeP 1860. Eight units are used for each beam. For thecross prestressing, the BBRV system, which is not liable to wedgesettlement, was chosen. This was due to the relatively short length (approx. m), which means that the effect ofwedge settlement would have been too great on the extent of the prestressing. The average prestressing level in the Ushaped bridges is between and N/mm2. An additional plication arose at the pylon where the bridge is suspended with vertical guycables. There are three guy cables for each Ushaped beam which are carried via steelconduit