Optimal Placement for Buckling-Restrained Braces in Super Tall Building Structures Based on Grid Shear Deformation

Buckling-restrained braces (BRBs) dissipate dynamic energy by plastic metallic axial deformation. The energy dissipation capacity depends on the amplitude of axial deformation of the BRBs. The number of BRBs in certain project is commonly limited due to budget constraint. It is always desirable that the BRBs are to be installed in those places which can maximize the energy dissipation during earthquake. For super tall buildings, it is common practices that the BRBs are to be installed in those stories which large story drifts. The storey drift of certain floor is composed of two kinds of deformation, say the rigid body displacement and racking (shear) deformation. This paper proposes to use grid shear deformation (GSD) of each floor for the optimal placement of BRBs due to the fact that only shear deformation will induce energy dissipation. An optimal placement method was developed based on GSD in this study. A super tall building with belt truss frame core-wall structural system is exemplified to show the effectiveness of the proposed GSD based optimal BRBs optimal placement method. The results show that the optimal BRB placements obtained by the proposed GSD method match well with the theoretically best placements which can maximize the energy dissipation. The proposed GSD method can be generally applied for the optimal placement of BRBs in super tall buildings.