long-term behavior of frp-bar reinforced seawater sea sand concrete beams under load sustaining and environment weathering

Concerns have been raised regarding the long-term durability of frp-bar reinforced seawater sea sand concrete (swssc) members in coastal engineering structures. in this context, an experimental study was conducted to investigate the long-term flexural behavior of gfrp-bar reinforced swssc beams, which were subjected to sustaining loads and exposed to both natural and chamber-accelerated coastal environments. following the exposure period, twelve beams were tested under four-point bending loads. the results indicate that both the natural outdoor and chamber accelerated environments exhibited higher load-carrying capacity and lower deflection than the natural indoor environment. the load-carrying capacity showed an improvement ranging from 10.3% to 34.8%, while deflection decreased by 6.5% to 19.9% when compared to the indoor environment. however, the presence of seawater and sea sands in swssc beams resulted in a reduced load-carrying capacity compared to normal concrete (nc) counterparts, with the reduction reaching up to 15.8%. furthermore, an increase in the sustaining load led to decreased load-carrying capacity but increased deflection, with values of 26.0% and 11.0%, respectively. to evaluate the appropriateness of current modern design codes, the load-carrying capacity and ultimate deflection of both nc and swssc beams were calculated and compared with the test results. the analysis revealed that the american code aci440.1r-15 and chinese code gb50608-2020 exhibited a conservative approach in predicting bending moment capacity. additionally, the american code aci440.1r-15 and canadian code csa s806-12 underestimated the ultimate deflection, whereas the chinese code gb50608-2020 overestimated it. these findings provide valuable insights for designing coastal structures using gfrp-bar reinforced swssc materials. © the author(s), under exclusive licence to the iran university of science and technology 2023.