Seismic Performance of High-Rise Structure Incorporating Frame-Core Decoupling and Inter-Story Isolation Mechanisms

Abstract

To improve the seismic performance of the frame-core structure for high-rise buildings, the frame and the core may be decoupled via flexible damping connections that are installed throughout the building height. Although the frame-core decoupling shows proper mechanical feasibility, the all-height decoupling between the frame and the core enlarges the drift demand of the former at the lower stories, while the function of the flexible decouplers on such stories is not fully demonstrated. Given these drawbacks, a novel frame-core system is proposed in this paper. The proposal is characterized by: 1) conventional rigid connections between the frame and the core at the lower stories, 2) flexible damped frame-core connections at the upper stories, and 3) inter-story isolation (ISI) in the frame at the bottom level with flexible frame-core connections. The structural configuration ensures a well-controlled frame drift, a reduced inertial load transmitted from the frame to the core, and an enlarged energy-dissipation of the flexible frame-core connections. By detailing the structural configuration and constructing the stiffness and damping matrices, the dynamic properties, seismic response, and energy dissipation characteristic of the proposed structural system are analyzed. Several key parameters that may influence the performance of the structure, e.g. properties of the inter-story isolation, flexibility and damping of the frame-core connection, among others, are discussed. Response history analyses show that: by incorporating both the frame-core decoupling and the ISI, the structure exhibits a hybrid aseismic mechanism, and the seismic demand of the system notably decreases. The energy-dissipating efficiency of the flexible decouplers significantly increases. Though a better seismic-mitigation performance is obtained when the position of the isolation layer gets lower, it is promising to set the ISI in the middle of the frame given the effective collaboration of the frame-core decoupling and the ISI mechanisms.

Keywords: high-rise structure, frame-core structure, substructure decoupling, viscoelastic damper, inter-story isolation, building mass damper