Technical challenges in the design of prestressed concrete precast beams with dry and smooth joints in bridge construction

A third terminal is currently being built at Frankfurt Airport. The connection of Terminal 3 to the main complex of the airport will be by means of a new, autonomous passenger transport system (PTS), which is to run on an elevated viaduct over a length of about 2.5 km. As one type of construction form for the viaduct, up to 40 m long girders are designed as prestressed concrete precast beams. Their special feature is the way in which individual girder elements are joined – the segments are fully precast with smooth, dry and non-toothed joints in the factory and joined together by means of post-tensioning. Unlike the load transfer in conventional, keyed joints with shear keys arranged on the segment face, the shear resistance in plane, smooth joints is generated exclusively by the friction generated by the clamping force across the joint. Even though there already are findings and experiences with smooth joints which are transferring loads via friction (e. g. in wind turbines), the special feature of the PTS in Frankfurt is the first application of this design principle in bridge construction by Max Bögl for a highly frequented track with high fatigue loads. This paper deals with the special features of design and verification as well as the high demands on the smooth joint in the manufacturing process.


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