A novel damped substructure outrigger (DSO) system for seismic response control of high-rise buildings

Damped outrigger (DO) systems are widely recognized as effective passive control schemes in mitigating the vibration response of high-rise buildings under earthquakes. The disconnection between the outer outrigger and perimeter column in DO systems, however, still presents a potential threat to structural safety. Therefore, a new type of damped substructure outrigger (DSO) system is introduced in this study. The DSO system is composed of a main structure and substructure, where the main structure includes the perimeter column, outriggers, and core tube. The substructure is formed by a conventional shear-type structure. A simplified analysis methodology is proposed for simulating the seismic behavior of the DSO system, wherein the DSO system is simulated using a cantilever beam incorporating a damped substructure and multiple rotational spring-dampers. The proposed analysis methodology is validated through a numerical example, demonstrating a high level of concurrence with the finite element method and yielding precise results. The optimal design of the DSO system is conducted based on the H ∞ criterion, aiming to simultaneously balance the seismic response of both the main structure and substructure. The analysis reveals that the performance index is substantially affected by the stiffness ratio, with a higher performance index generally observed when there is a larger stiffness ratio. The control performance of the DSO system is examined via a series of shaking table tests. It is confirmed that, in comparison to conventional outrigger (CO) systems, the DSO system exhibits superior control performance in mitigating structural seismic responses. Moreover, the main structure of the DSO system demonstrates enhanced control performance compared to its substructure.