Long-term behavior of CFRP prestressed concrete beams

This paper presents an experimental program designed to examine the long-term behavior of carbon fiber reinforced polymer (CFRP) pretensioned concrete beams under sustained load conditions. The test program consists of three beams prestressed with CFRP rods and one beam prestressed with steel prestressing strands. The pretensioned beams were subjected to a sustained load of 53 kN (12 kips). Deflections and prestressing reinforcement strains at midspan were monitored for a period of 651 days. An analytical model was developed to predict the time-dependent behavior of the pretensioned beams. The experimental results show satisfactory behavior of CFRP pretensioned beams compared to the steel pretensioned beam. The ratio of long-term to instantaneous deflection at midspan was observed to increase with the level of prestress force. The steel pretensioned beam exhibited higher long-term midspan deflections than the companion CFRP pretensioned beams.