Xie, Zhao, and Meng 2020
A dual tube self- centering buckling- restrained brace system (SC- BRB) is fixed with frictional fuses in order to increase the energy dissipation capacity of the system, while decreasing the residual deformation. Two versions of the fuses are first tested in order to optimize the system in place in the final specimens, and then ¼- scale specimens of twelve story buildings are loaded into an actuator to undergo quasi-static cyclic loading.
System Concept
The SC- BRB system consists of an inner and outer tube that are located along the core of the building. The two systems in place in the SC-BRB system are the energy- dissipation system and the self- centering system. The energy- dissipation system consists of two parallel core plates that are connected to the inner and outer tubes through welded connections. There are also filled plates welded to the inner tubes in order to prevent in-plane buckling of the plates. The self-centering system consists of the inner and outer tubes as well, along with basalt fibre-reinforced polymer tendons (BFRP tendons) in order to maintain the system’s centering capacity.
The frictional fuse is an experimental annexation to this system. It consists of two outer friction plates clamped to an inner friction plate at one end, and bolted to the beam system on their other end. The frictional fuse is used to increase the deformation capacity of the system by absorbing seismic energy through deformation in order to protect the beam system from inelastic deformation.
Experimental Study, Results and Discussion
The first experimental study performed within this paper was a test on two test specimens of the frictional fuse system. The two fuses, Specimen A and Specimen B, were fixed to the seat of the tested machine on one end and fixed to an actuator on the other end. The different tests performed on the test specimens were to adjust the bolt torque in order to adjust the sliding frictional force, and then to compare the performance of the different test specimens under different amplitudes of load conditions. It was found that the performance of each specimen was stable unless the frictional contact surface was too small, under which conditions the frictional surface will corrode and the frictional coefficient will decrease.
Following the test studies of the two different fuses, two specimens at a ¼- scale of the SC-BRB fixed with Specimen A of the frictional fuse were also fixed to an actuator and were tested under quasi-static cyclic load conditions. The actuator was fixed with a displacement gauge and force sensor in order to determine both the axial stress and interstory drift of the specimens. The experimental study was used to verify the increase in deformation capacity and seismic energy dissipation of the SC-BRB system with the frictional fuses. The frictional fuse did prevent the fracture of the BFRP tendons, and increased the energy dissipation capacity of the system, though there was some residual deformation in the beams. It is suggested that the fuses only be activated at a high displacement in order to prevent the deformation of the beam system.
Reference
Xie, Q., Zhao, Z., and Meng, S. (2020). “Experimental Investigation of the Hysteric Performance of Self-Centering Buckling-Restrained Braces with Friction Fuses,” Engineering Structures, 203. 109865.