Study on influence factors of bearing capacity and serviceability of BFRP reinforced seawater and sea-sand concrete beams

To improve the bearing capacity and service performance of BFRP-reinforced seawater and sea-sand concrete beams, it was proposed to use textile-reinforced ECC (textile reinforced ECC, TRE) to partially replace concrete in the tension zone to limit the development of cracks and deflections. The research parameters included the reinforcement ratio, section height, reinforcement diameter and composite layer. The results show that the increase of the reinforcement ratio (or axial stiffness) and the section height leads to an increase of the bearing capacity, and a decrease of the deflection and crack width. The use of BFRP bars with a smaller diameter can reduce the crack width, but has no significant effect on the bearing capacity and deflection. The TRE composite layer can improve the cracking load and bearing capacity to a certain extent. In addition, the TRE composite layer can effectively delay the stiffness degradation and reduce the deflection and crack width of the beam in service stage. These effects increase with the increase of composite layer thickness and the number of textile layers. Compared with the control beam, the deflection and crack width of the composite beams under service load are reduced by up to 63.2% and 71.3%, respectively. Finally, based on the section analysis method, the calculation method of the bearing capacity and the formula of the optimal reinforcement ratio of textile for the TRE composite beam was given. The calculated values of the bearing capacity are in good agreement with the test values, with the relative error being generally below 16%. © 2021, Editorial Office of Journal of Building Structures. All right reserved.