Flexural behavior of BFRP reinforced seawater sea-sand concrete beams with the TRE shell under the coupled action of dry-wet cycles and load

In order to study the effect on the flexural behavior and durability of the textile reinforced engineered cemen-titious composites (TRE) shell for specimens under a dry-wet environment, the basalt fiber reinforced polymer (BFRP) reinforced seawater sea-sand concrete beams composited the TRE shell were subjected to the dry-wet cycles and the coupling of dry-wet cycles and the sustained load. The failure pattern, ultimate bearing capac-ity, deflection and crack width of composite beams under different dry-wet cycles, TRE shell shapes and sus-tained loadings were studied, and the ductility of beams with the TRE shell was further evaluated by energy and deformation. The experimental results showed that all composite beams with the U-shaped TRE shell suffered from the failure of concrete crushing. During the test, the interface of the TRE shell and concrete was debonded for all beams with the TRE shell, and the deformation of beams with TRE shell recovered after unloading. The ultimate bearing capacity of beams decreased slightly with the dry-wet cycles, while the deflection and crack width of the specimens hardly changed significantly. The ultimate bearing capacity of beams with the TRE shell decreased with the stress level of the sustained loading, whose stiffness increased and the cracks became sparse. Crack width decreased with the suatained load before the interface debonding, but the opposite phenomenon occurred after the interface debonding. From the ductility evaluation, the energy absorption index of beams with the U-shape TRE shell is higher than that of the BFRP reinforced seawater sea-sand concrete beam, indicating that TRE shells can effectively improve the energy dissipation capacity of beams.