Flexural Strengthening of RC Beams with Prestressed CFRP Strips: Development of Novel Anchor and Tensioning System

Abstract External prestressing with carbon fiber-reinforced polymer (CFRP) strips is currently a well-developed and widely used technique to strengthen reinforced concrete structures subjected to bending. This paper presents the development and experimental investigation of a novel anchor and tensioning system for the flexural strengthening of RC elements with prestressed CFRP strips. The research on anchorages comprised a series of small-, medium-, and full-scale tensile tests, which resulted in the development of a new anchorage type with a tensile capacity of 200 kN, as well as the relevant tensioning device. This new system was subjected to comprehensive tests on RC beams in the laboratory, in which the efficiency, feasibility and ergonomics of the system were examined. The CFRP prestressed beams exhibited a more than 50% higher carrying capacity than that of the reference beam without strengthening. They also proved to have lower deflections as well as a lower number of cracks. As a result of the research, an effective strengthening system was developed and examined in the laboratory. Its efficiency and feasibility were also confirmed in the field tests on a strengthened existing bridge, and recently it has been successfully implemented in practice.