سیستمهای دمپری یکپارچه در ساختمانهای بلند
Abstract
1. Introduction
2. Background
3. Motion performance based-design
4. Simulation methods
5. Application of the PBD methodology on a case study building
6. Conclusions
Acknowledgement
Appendix A. Spectral approach for wind load time series simulation
References
Abstract
The application of performance-based design (PBD) is gaining increasing interest in the wind engineering community. A popular design approach to minimize wind induced vibrations in flexible civil structures is to size structural stiffness and supplemental damping systems in order to restrict the motion to a given threshold for providing safety and comfort, while ensuring that structural components meet strength requirements. In this paper the PBD paradigm is extended to wind excited tall buildings equipped with motion control systems. The objective is to improve the design of damping systems under different wind events while considering maximum acceleration as performance measure. In addition, since the installation of damping devices implies additional costs (e.g., installation and maintenance costs) while it helps decreasing the costs associated with performance failure, a life-cycle analysis (LCA) is integrated in the PBD. In the LCA framework, the percentage of building occupants affected by discomfort and motion sickness caused by excessive wind-induced vibrations is considered to account for the consequences of different target performance levels. The developed PBD is applied to a 39-story building that has documented issues with excessive vibrations under wind events. The wind load is simulated as a multivariate stochastic process, in the time domain. Two passive vibration mitigation strategies are investigated: viscous and friction dampers, both designed to meet the target performance levels. LCA are conducted for the building equipped with each damper type, and benchmarked against the one without dampers. Results show that the PBD leads to a rational and economically effective approach for the design of the damping systems in wind excited tall buildings.
Introduction
Performance-based design (PBD) has shown to be an effective philosophy to create risk consistent designs within the seismic engineering community [1–۳]. In the past years, numerous attempts have been made to extend the application of PBD to other hazards such as wind load [4–۶], fire [7], vehicle collision [8,9], and seismic pounding [10]. In wind engineering, many of the proposed PBD procedures have been devoted to tall buildings, with particular focus on the serviceability limit states [11–13]. The use of passive supplemental energy damping systems to improve the performance of high-rise structures under wind load is now widely accepted [14,15]. However, a PBD methodology that integrates the design of passive damping systems in a tall building has yet to be developed. In motion engineering, the idea of PBD is to minimize structural vibrations by appropriately sizing supplemental damping systems in order to restrict the motion to a given threshold for providing safety and comfort, while designing the structural stiffness to ensure that structural components meet strength requirements [16]. This requires the development of a PBD procedure for tall buildings that includes the design of the motion control devices. Passive damping systems, such as tuned-mass damping, viscous damping, and base-isolation, are widely used to enhance the structural performance under natural hazards. Some of the attractive features of this technology are the high reliability of the devices, the robustness against possible mechanical failures, and their inherent stability. In the wind hazard case, passive damping systems are generally designed for a predominant wind speed, without considering temporal and spatial variations of the wind load throughout the life span of the structure [17–19].