Flexural behavior of seawater sea-sand coral concrete-UHPC composite beams reinforced with BFRP bars

A new type of cost-efficient concrete beam that is suitable for island environments, namely, a seawater sea-sand coral concrete (Coral-SWSSC)-ultrahigh-performance concrete (UHPC) composite beam reinforced with basalt fiber-reinforced polymer (BFRP) bars, was proposed in this paper. In these beams, the top 1/8 of the Coral-SWSSC was replaced with UHPC, and both the longitudinal bars and the stirrups were BFRP reinforcements. In addition, a new type of BFRP-wrapped steel tube (BWST) was placed in the tension zone of the beams as additional tensile reinforcement to further increase the performance. The test results showed that compared with the pure BFRP bar-reinforced Coral-SWSSC beams, the new hybrid beams exhibited much better comprehensive bending performance. The ultimate bending capacity, ultimate displacement, and energy consumption were effectively improved by adopting the UHPC replacement layer alone, and the flexural stiffness was improved significantly by adopting the BWST alone. However, when the UHPC replacement layer and the BWST were adopted simultaneously, the abovementioned performance metrics were all improved. The new hybrid beam proposed in this paper has good future application prospects in remote island environments. (C) 2020 Elsevier Ltd. All rights reserved.