Short- and long-term performance of the novel additional aluminum alloy ribs anchored CFRP reinforced pretensioned PC beams

Abstract

The anchorage shortage in FRP (fiber reinforced polymer) reinforced pretensioned prestressed concrete (PPC) elements has frequently led to the uncontrollable slippage. To provide a practical answer to this issue, an innovative additional aluminum alloy ribs (ARs) anchorage was developed. This study mainly investigated the effect of the ARs anchorage on the performance of the CFRP reinforced PPC beams subjected to flexural loading. Two kinds of loading types (i.e. short- and long-term loading) and two sustained loading levels (i.e. 40% and 75% of the short-term capacity) for the tested beams were included. The results indicated that ARs anchorage could shorten the transfer length and improve the short-term diagonal concrete cracking load in PPC beams by as much as about 20%. In addition, the ARs anchorage presence was capable of reducing the long-term slip by more than 2 times after the beams were loaded up to 120 days, and meanwhile delaying the diagonal concrete crack width increase by up to 70.9%-86.4%. Due to such merits, a less long-term prestressing loss was found and the long-term deflection of the beam was decreased by 50.8%–82.9%. More significantly, one of the unanchored PPC beam failed by complete bar slippage after being loaded for 146 days, whereas the ARs anchored beams have successfully sustained the 584-day loading and showed a convergent slip development. Finally, two calculation methods for the FRP reinforced beams were adopted to predict the long-term deflection of the tested beams, and the analytical and experimental results were compared and analyzed.