Strengthening of existing infrastructure with concrete screws as post-installed reinforcement

In many parts of the world, infrastructure has reached a critical age. Due to enviromental influences, higher loads or changes of code regulations many structures in this field show a lack of resistance concerning shear, punching and bending. During the last decade a new strengthening system for existing structures based on the use of so called concrete screws was developed. These special concrete screws are installed in predrilled holes in the concrete structrues and act as post-installed reinforcement. The big advantages of this system are a significant rise of the resistance of the existing structures, the easy and fast installation without disturbance of the traffic and the low costs of the measures. The contribution deals with the development of the strengthening method especially for shear and punching loads, the laboratory tests and numerical investigations. Also a design approach based on Eurocode provisions is presented. These calculation rules and installation principles are embedded in a technical approval order to allow the application for all practical engineers. Finally some best practice projects of bridges, tunnels and parkdecks strengthened with this method will be presented. Especially when we look at the upcoming questions regarding sustainability, minimizing CO2-emissions and the efficient use of natural resources the extended use of existing structures by strengthening these structures will gain a huge importance in the future.