Research on the durability of FRP-bonded concrete beams subjected to a performance probabilistic design method

FRP-bonded concrete enhances the structural strength and extends the service life, yet durability challenges remain pronounced. Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) are employed to bond precast cracked concrete beams. Three adverse environments are established: freeze–thaw cycle, sulfate erosion, and salt-freeze coupling erosion conditions. The degradation patterns of specimens under single erosion and coupled erosion environments are compared using electron microscopy, mass loss analysis, load–displacement curves, and bottom strain measurements. The disparities in degradation mechanisms between coupled and single erosions are also examined. The findings reveal a noteworthy disparity in mass loss between a singular freeze–thaw cycle environment and a salt-freeze coupled environment. Following 400 h of exposure to three adverse conditions, the strength deterioration in CFRP-bonded concrete flexural specimens amounted to 42.0%, 14.6%, and 66.3%, respectively. Similarly, GFRP-bonded concrete flexural specimens exhibited strength losses of 52.3, 21.9, and 67%. Significantly, the degradation induced by salt-freeze coupled erosion surpassed that of individual adverse conditions. This phenomenon is attributed to sulfate intensifying crack damage on the FRP-concrete bonding surface caused by freeze–thaw cycles. The instability of specimen strength due to erosion over time is considered by applying the performance probability design method, leading to the correction of test results. Ultimately, a highly accurate prediction model for the strength of FRP-bonded concrete beams under three adverse environmental conditions is developed.