Bearing behavior and serviceability evaluation of seawater sea-sand concrete beams reinforced with BFRP bars

Abstract

Currently, the combination of fiber reinforced polymer (FRP) and seawater sea-sand concrete (SWSSC) is becoming a popular research topic. In this paper, the bearing behavior and serviceability evaluation of SWSSC beams reinforced with basalt FRP (BFRP) bars were studied. A total of 10 beams with lengths of 2100 mm, widths of 180 mm, and heights of 300, 250 and 350 mm were constructed. The experimental parameters included the reinforcement ratio, section height, bar diameter and bar type. The test results were discussed in terms of failure modes, bearing capacity, deflection and crack width. With an increase in the reinforcement ratio, the failure mode of the specimen transitions from tensile failure, to balance failure and ultimately to compressive failure. The flexural capacity, crack width and deflection of the FRP-SWSSC beams are much higher than that of a steel-SWSSC beam. Increasing the reinforcement ratio or the section height can increase the bending stiffness of the beam, which consequently increases the bearing capacity and reduces the strain, deflection and crack width of the beams. However, beams with similar axial stiffnesses exhibit similar flexural behaviors. BFRP bars with smaller diameters have better bonding properties with the concrete, thus reducing the crack width, while the bearing capacity and deflection are not affected. The curvature limit of 0.005/d can meet the deflection and crack width serviceability requirements of BFRP-SWSSC beams. In addition, the experimental results are compared with the existing design specifications, and at 0.3Mn, both the ACI 440.1R-15 and GB 50608-10 specifications underestimate the deflection value of the test beam, while the CSA S806-12 specification conservatively overestimates the deflection value of the beam.