Structural behaviour of small GFRP-reinforced seawater sea-sand fiber reinforced concrete culverts

This study investigates the structural behaviour of fiber-reinforced seawater sea-sand concrete (FR-SWSSC) culverts employing glass fiber-reinforced polymer (GFRP) bars as internal reinforcements. Eighteen small concrete culverts with a total width of 470 mm and two different total heights of 425 mm and 365 mm, conforming to the Australian standard were subjected to experimental evaluation. The study investigated various parameters, including fiber type (macro polypropylene (PPL), macro twisted polypropylene (TPPL), micro polyvinyl alcohol (PVA), and micro basalt (BA) fibers), fiber hybridization, compression GFRP reinforcement, crown thickness, haunches, and concrete compressive strength. A comprehensive analysis of culvert behaviour was conducted, encompassing load at first crack, crack propagation, load-displacement response at the mid-span of the crown, ultimate load-carrying capacity, energy dissipation, ductility, and failure mode. The results showed that punching shear at the crown was the prevalent failure mode for FR-SWSSC culverts. The ultimate shear capacity, cracking strength, and energy dissipation of culverts were significantly enhanced by the addition of fibers, particularly hybrid fibers (PVA/BA and PPL/PVA). Partial substitution of PPL fiber with PVA resulted in a substantial increase in ultimate strength compared to PPL fiber culvert. The performance and effectiveness of fibers, especially hybrid ones, were significantly influenced by the presence of compression GFRP reinforcement and reduced crown thickness. Haunches had a profound impact on the shear strength of GFRP-reinforced culverts and significantly altered the performance of fibers. This study demonstrates that FR-SWSSC culverts reinforced with GFRP bars and discrete fibres can serve as a sustainable alternative to conventional concrete culverts.