Post-tensioning systems for the strengthening of structures

Abstract

Exponentially increasing loads, aging of bridges and new design and construction specifications request the strengthening of numerous bridges and concrete structures throughout Europe. Based on a continuous development and optimization for strengthening applications today a variety of post-tensioning systems are available in order to compensate the specific local and global lack of former design methods and to improve the existing infrastructure for years to come. Summarizing the different external and internal post-tensioning systems depending on the specific strengthening application and stressing force range this report provides an overview of today’s wire, strand and bar tendon based systems focussing on corrosion protection methods, installation and stressing aspects. A high quality standard, fast and secure installation under traffic in combination with flexible project related solutions consequentially caused over the last years a development to factory prefabricated tendons shipped already corrosion protected and ready-to-use to the construction site. Referring to executed projects in Germany and Belgium the report points in detail to the different post-tensioning related strengthening applications and presents in examples special aspects of the installation process. In longitudinal direction external tendons are commonly installed to increase the resistance of the structure against traffic loads. Prefabricated wire based tendon systems provide solutions with a minimal intervention to the existing structure. New external prefabricated bar tendon systems offer solutions for local deficits in shear resistance induced by insufficient shear reinforcement. The combination of optimized post-tensioning systems in strengthening projects therefore helps to comply with the demands for a reliable, economical and sustainable infrastructure.