Fatigue performance of anchorage for CFRP tendons affected by water infiltration

This study is concerned with the effect of moisture on the fatigue performance of the anchorage for CFRP tendons. Series of tests were carried out on the pre-conditioned adhesively bonded anchorages and wedge-bonded anchorages so as to investigate the fatigue behavior of anchorages under different moisture and loading conditions. The structural responses of the moisture-conditioned anchorages were analyzed during cyclic loading, including the temperature rise in the anchor zone, sleeve strain, tendon slippage, and residual ultimate tensile capacity (UTC). Thereafter, the trend of water infiltration in the anchor zone was inspected. The results show that the structural responses of the anchorage are influenced significantly by the stress ratio and the moisture condition, regardless of whether the anchorage is adhesively bonded or wedge-bonded. Moisture-conditioning leads to the increase of the temperature rise and the tendon slippage. Moisture-conditioned anchorages have a much smaller sleeve strain compared to the dry anchorages under the same cyclic loading conditions. Moreover, a lower the stress ratio will intensify the detrimental effect of moisture-conditioning; thereby resulting in a severer degradation in the UTC. The water absorption of the anchorage is linearly related to the square root of the immersion duration in the early stage of water immersion. The increase of water absorption induces the decrease of Young's modulus and the tensile strength. It consequently weakens the fracture toughness of bonding medium, which accounts for the degradation of the UTC of the anchorage. (C) 2020 Elsevier Ltd. All rights reserved.