A study of fiber-reinforced plastics for seismic bridge restrainers

Easily installed and inspected fiber reinforced plastic (FRP) as an alternative to steel for restrainer construction to reduce bridge hinge movements during earthquakes was examined. Glass, carbon, and hybrid (glass/carbon) restrainers were constructed and dynamically tested in the large-scale structures laboratory. Work included: (1) Tensile tests on FRP strips and on FRP/concrete bond versus loading rate; (2) FRP restrainer development, including dynamic testing; (3) Shake table data analysis and comparisons of FRP, steel, and SMA restrainer performance; (4) Development of a FRP restrainer design method. Findings confirm FRP restrainer potential for future implementation to structures. Results include: (1) FRP strength is strain-rate insensitive; (2) FRP/concrete bond strength is a function of concrete shear strength and is strain rate sensitive; (3) Flexible restrainer construction and restrainer/concrete bond methods are demonstrated; (4) A simplified FRP restrainer design method, more realistic than AASHTO, and that considers bridge structure dynamic characteristics, is proposed.