Enhanced service life of existing infrastructure buildings by use of concrete screw anchors as post-installed shear reinforcement

Abstract

In the last decades, traffic on railways and roads has increased significantly in Central Europe. On the other hand, the existing infrastructure mainly origins from the late 1950s to the 1970s. This applies also for the existing bridge and tunnel infrastructure which is now up to 60 years old. Due to this age and new standards in the current codes, quite often the amount of shear reinforcement does not fulfil the current design code rules. As a replacement of existing structures is often highly unsustainable, methods to improve the shear strength are needed. Therefore, a new system for post-installed shear reinforcement by the use of concrete screws was developed at the University of Innsbruck in the last years. The idea is to use concrete screw anchors - already known as anchoring element - aspost-installed reinforcement. In over 60 shear tests with girders and slabs the excellent applicability  of concrete screw anchors as post-installed shear reinforcement has been proven. Also shear tests with cyclic loading were performed prove the use for dynamically loaded structures, such as bridges. Based on these test results a design approach was determined to meet the Eurocode-2 assessment standards.Several pilot-projects with concrete screws have been realised in Austria and Germany. For example a rail-road-bridge over a German highway with a remaining service life of zero years was strengthened to a new service life of over 20 years. Also a city-centre tunnel in Munich which was erected below a historic building is currently strengthened under ongoing traffic in the tunnel using concrete screw anchors as post-installed reinforcement.