Development of Non-metallic Anchorage System for FRP Tendons

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The authors have newly developed a non-metallic anchorage system using highly expansive material. The results obtained in this study are summarized below.(1) Non-metallic anchoring devices can be made of CFRP reinforcement and epoxy resin mortar.(2) Double layr CFRP spiral reinforcement is able to resist the inner expansive pressure up to more than 40 MPa of highly expansive material. The CFRP spiral hoop inside with congested pitch is also effective to resist tensioning force of tendon.(3) Axial stiffness, needed to resist the prestressing force, can be obtained by reinforcing with CFRP strand/rod. Reinforcement ratio of 4-5% is found to be appropriate from the viewpoints short/long term displacement and workability of resin mortar grouting.(4) Ultimate load of the non-metallic anchoring devices in compression is more than 400 kN.The prestressing force about 100kN is safe.(5) The decrease of prestressing force is mainly caused by the slippage of CFRP tendon at the end of anchoring device. However, the influence of slippage on the decrease of prestressing force becomes negligibly small when the length of tendon will be much longer in practice.(6) The prestressing system with newly developed non-metallic anchoring devices is considered as a practical method.