Experimental Investigation of the Hysteretic Performance of Dual-Tube Self-Centering Buckling-Restrained Braces with Composite Tendons

This paper presents the results of experimental testing a novel dual-tube self-centering buckling-restrained brace (SC-BRB) with pretensioned basalt fiber-reinforced polymer (BFRP) composite tendons. Cyclic tensile experiments are first conducted on two sets of BFRP tendons with different diameters. The results confirm that the BFRP tendons have a stable cyclic elastic modulus and sufficient elongation capacity, making them suitable for use as the self-centering tendons in SC-BRBs. Quasi-static experiments are performed using two dual-tube SC-BRB specimens with different core plate areas. Before the failure of the self-centering system, both specimens stably exhibit the expected flag-shaped hysteresis response, with a relatively small residual deformation. The internal forces in the BFRP tendons and the gaps between the tubes and the end plates are measured to validate the performance of the self-centering system. Both specimens meet the requirements for ultimate ductility and cumulative ductility in braces. For a similar initial pretension, a greater core plate area results in greater residual deformation; however, the cumulative energy dissipation and the equivalent viscous damping are also greater.