| FRP cables have been used as tendons for pre-stressed concrete or ground anchors. The tensile load relaxation of FRP cables is usually verified by stress relaxation tests for 1,000hours in a laboratory. However, demonstrative data for long term behaviour of FRP cables have not been sufficiently provided, and more empirical studies are required, particularly for stress relaxation. The authors have carried out outdoor exposure tests for 17 years to verify the long-term durability. FRP cable specimens using carbon, aramid, glass, and vinylon fibers, exposed various conditions such as several initial prestressing tensile load, with/without direct sunlight radiation and salt splash conditions. The specimens were retrieved and investigated with several properties including the residual prestressing tensile load. The results suggest that practical durability of carbon and aramid FRP cables seems to be still good, but initial loading level should be carefully considered for glass and vinylon FRP in the case tensile load permanently applies. |
