IMPROVED SUSTAINABILITY IN POST-TENSIONING BY REPLACEABLE INTERNAL UNBONDED TENDONS

The bridge design with external Post-tensioning has been established and applied successfully in the last two decades. In Germany consequently the development moved towards using unbonded tendons also internally. In comparison with solely externally prestressed structures the lever arm in box girders can be improved significantly and the application is also interesting for massive cross section design like T-beams. On basis of its established SUSPA-Wire Ex system for external Post-tensioning DSI has developed SUSPA-Wire internal with a fully restressable and replaceable tendon meeting the requirements of a suitable PT-system for the new concept of PC structures. Several pilot projects have been carried out in the last years. The replaceability has been proven recently on a road bridge project in South Germany on a tendon of some 84 m length. The insitu test has been supervised by an independent laboratory and additionally reviewed by an accredited expert.