Glass-fiber reinforced polymer (GFRP) reinforcement is being used in bridge decks as a replacement for steel reinforcement. It is thought that since the GFRP reinforcement does not corrode, it can be a more sustainable material for reinforced concrete structures. Limited research has been performed to quantify the time-variant capacity of GFRP reinforcement embedded in concrete and thus the applicability of the environmental factor found in American Concrete Institute (ACI) 440 is questionable. A Bayesian approach was used to develop time-variant probabilistic capacity models based on data of the capacity of GFRP reinforcement embedded in concrete for a period of 7 years. These models are used herein to assess the time-variant structural reliability of a bridge deck. The results on the ability of GFRP-reinforced bridges to withstand future loads can be used to optimize the allocation of resources for maintenance, repair, and rehabilitation for the design and construction of sustainable bridge systems.