Enhance the Resilience of Steel Outrigger by Equipping GFRP Tendons and Viscoelastic Material

Seismic resilience has emerged as a trend in the seismic design of buildings, with self-centering components or systems used as an effective method to improve seismic resilience. The outrigger is an essential component for resisting the lateral load in super-tall buildings. However, the diagonal member of the traditional outrigger is prone to buckling, resulting in excessive residual deformation and repair difficulties after earthquakes. A novel self-centering outrigger (SCO) with desirable energy dissipation and self-centering capacity is proposed in this paper. In the SCO, the traditional steel diagonal member is replaced with a new self-centering viscoelastic brace (SCVB). The seismic performance of the SCVB with a total length of 2.2 m is investigated using the low cyclic loading test, with results demonstrating that the SCVB exhibits a flag-shaped hysteretic response. Based on the experiment results of SCVB, a refined finite element model of the proposed SCO is developed to evaluate the seismic performance, then the hysteretic responses of the traditional outrigger and SCO under different load conditions are compared. Results show that the hysteretic curve of the proposed SCO is flag shaped, with stable stiffness and desirable energy dissipation and self-centering capacities. Even at a large loading displacement, a small amount of residual deformation will occur, but it is reduced by 75.52% compared to a traditional outrigger, while the strength is increased by 14.37%. Finally, the influence of the key parameters of SCVB on the hysteretic behavior of SCO are discussed, providing reference for future seismic design of the SCO.