Behaviour of BFRP tendon systems under cyclic loading and its influence on the dual-tube SC-BRB hysteretic performance

Abstract

Basalt fibre-reinforced polymer (BFRP) is an excellent pretensioned tendon material due to its high elongation, and it has been used in the self-centering buckling-restrained brace (SC-BRB). During previous experiments on SC-BRBs, although the BFRP tendon did not cause anchorage slip failure, pretension loss occurred. To determine the cause of the pretension loss, in this paper, cyclic tensile tests were conducted on multiple sets of BFRP tendon systems. Based on the experimental results, the pretension loss of the SC-BRB was due to the deformation of the colloid in the anchor under cyclic loading, and the regression formula of the colloidal deformation of the anchor was established. According to the results of a quasi-static experiment on a SC-BRB, the BFRP tendon can provide a reliable self-centering restoring force for the brace, and the accuracy of estimating the pretension loss based on the regression formula is demonstrated. Finally, a rheological model that can accurately describe the hysteresis performance of the SC-BRB and consider the pretension loss is established. Based on this model, the influence of the pretension loss on the brace performance is studied.