Development, Shake Table Testing, and Design of FRP Seismic Restrainers

The development and performance of fiber-reinforced polymer (FRP) fabrics as an alternative to steel for restrainers to reduce bridge relative movements at hinges during earthquakes was explored. Glass, carbon, and hybrid (glass/carbon) restrainers were developed and tested on a representative in-span hinge using a shake table at the large-scale structures laboratory at the University of Nevada, Reno. The components of the study presented in this article are: (1) the FRP restrainer development and testing; (2) comparisons among FRP, steel, and shape memory alloy restrainers; and (3) development and evaluation of a simple restrainer design method and a numerical example. Important findings of the study were that compared to steel restrainers, the FRP restrainers were effective in substantially reducing the relative hinge displacements and pounding at hinges. The method to develop the flexible portion of the FRP restrainers and the bond to superstructure was successful in accomplishing the target performance. The proposed restrainer design method provides a rational yet simple tool to design FRP or other types of restrainers.