Self‐centering viscoelastic diagonal brace for the outrigger of supertall buildings: Development and experiment investigation

Summary This paper aims to improve the seismic performance of outriggers within supertall buildings and eliminate the defects of obvious degradation of stiffness, low energy dissipation capacity, and large residual deformation after the buckling of traditional diagonal members by presenting a new type of outrigger. The traditional profiled steel diagonal member is replaced with a self‐centering viscoelastic diagonal brace (SC‐VEDB) in the proposed outrigger, providing enhanced energy dissipation and self‐centering capacity. The new SC‐VEDB is composed of the inner and outer steel tubes, viscoelastic materials, and prestressed tendons. Energy dissipation capacity is produced by the shear deformation of viscoelastic materials, whereas prestressed tendons provide the self‐centering capacity. The working mechanism of SC‐VEDB is first theoretically analyzed. Following this, two specimens with a length of 2.2 m were designed, fabricated, and tested under low cyclic reversed loadings within different frequencies and pretension forces. The results confirm that the hysteretic curve of SC‐VEDB has a typical flag shape, which imparts the stable stiffness, good energy dissipation, and self‐centering capacities. The activation force of SC‐VEDB is mainly determined by the initial pretension force, and the post‐activation stiffness predominantly depends on the stiffness of the prestressed tendons. Moreover, SC‐VEDB has better repairability, and the initial hysteretic behavior of the component can be quickly recovered by replacing the damaged prestressed tendons. A refined finite element model for SC‐VEDB is established to predict its hysteretic behavior, and the numerical simulation corresponds well with the experimental results. The maximum relative error of the initial elastic stiffness and ultimate strength is approximately 4.6% and 1.3%, respectively, which verifies the accuracy of the SC‐VEDB numerical simulation method.