Development of Strip Anchoring for CFRP Strengthening System

Prestressing of reinforced concrete structures with CFRP strips is highly effective and currently developing method of strengthening. Mechanical anchorages are usually used in this technology in order to introduce and permanently maintain prestressing force in the CFRP strips. The paper presents the results of static tests of CFRP strips anchorages used in strengthening system recently developed in Poland. The system consists of two main elements: mechanical steel anchorages mounted on both ends of a single CFRP strip and a relevant tensioning device. The tests included two types of anchorages: N-type with hybrid bonded/riveted joints between steel plates and CFRP strips and S-type with bonded/bolted joints. Both types of anchorages have been tested in axial static tests in five series. The anchorages in subsequent series were modified based on the test results and the conclusions of previous series. The main goal of the tests was to establish the carrying capacity and the efficiency of the anchorages. The experimental results allowed for significant increase of anchorages carrying capacity in comparison with initial design and showed that the S-type anchorages exhibited a higher values of carrying capacity as well as higher level of homogeneity.