Cyclic experiments and global buckling design of steel-angle-assembled buckling-restrained braces

Abstract

Compared with traditional BRB, the steel-angles-assembled buckling-restrained brace (SAA-BRB) is an innovative BRB with light-weight, accurate control of the geometrical dimensions, easy installation and convenient disassembly. The SAA-BRB is composed of an external restraining system and a cruciform-sectional inner core. The external restraining system is assembled by four steel angles with the connection of high-strength bolts, and the spacers are installed between the inner core and the restraining system. In this study, the hysteretic behavior of SAA-BRB was investigated by experiments and finite element (FE) simulations. Firstly, three SAA-BRB specimens with different restraining ratios were tested under cyclic loads to investigate the hysteretic performance. It was found that all specimens exhibited stable responses and satisfactory energy-dissipating capabilities during the whole loading process. Then, a refined FE model was established, and its validity in predicting the hysteretic responses of SAA-BRB was verified by the experiments. Moreover, based on the yielding criteria of the outmost fiber for the restraining member section, a design formula for the restraining ratio requirements to avoid global buckling of the SAA-BRB was deduced.Finally, extensive parametric analysis was conducted to verify the accuracy of the design formula by changing the geometric dimensions (the restraining ratio) of models. It was found that the proposed formula for the restraining ratio requirement could lead to a conservative prediction with reasonable accuracy, thus providing valuable references for global buckling design of SAA-BRBs in engineering practice.

Experimental of buckling restrained brace hysteretic performance with carbon fiber wrapped in concrete

“…Although the law of stiffness degradation is basically the same, there are differences in the stiffness values under the same displacement, which are mainly related to the frictional connection effect and the time when the anti-buckling supports enter buckling, and also related to the symmetry of the structure and supports. This phenomenon shows that buckling restrained braces can increase stiffness under small displacement, decrease equivalent stiffness under large displacement and increase energy consumption, which is conducive to reducing earthquake action [14,15].…”