یک روش طراحی پارامترهای ميراگر ويسکوالاستيک
Abstract
1- Introduction
2- The development of the EPRRC
3- Design of the VED parameters
4- Design example and verification
5- Conclusion
References
Abstract
The traditional design method of the elastic response reduction curve (ERRC) was used to design the parameters of the viscoelastic damper (VED), where the plastic behavior of the primary structure is neglected. Considering the structural plastic behavior, in this study, a direct design method is proposed to obtain the parameters of VEDs based on the elastic-plastic response reduction curve (EPRRC), which can illustrate the relationship between damper parameters and the response reduction effect in the elastic-plastic stage. First, the ERRC is developed to the EPRRC, and the differences between them are compared using the displacement and acceleration response difference ratios, which demonstrate an overestimated response reduction effect of VEDs in the elastic-plastic stage using the ERRC. Then, the corresponding design procedures are given based on the EPRRC by referring to the direct displacement-based design theory. Finally, a benchmark model is used to illustrate the effectiveness of this proposed design method by conducting a time history analysis. The analysis results indicate that the target story drift of the structure can be satisfied under different earthquake intensities using VEDs. Thus, based on this study, the development of the EPRRC can be considered worthwhile, and the proposed design method of VED parameters is easy to implement and is effective.
Introduction
Passive control systems using energy dissipation devices have been demonstrated to be effective for seismic damage mitigation of structures [1–4]. Four kinds of devices, friction dampers, metallic yield dampers, viscous dampers and viscoelastic dampers (VEDs), are often used. Among these devices [5–10], VEDs provide both supplemental damping and stiffness and show the characteristics of the phase angle difference of the force-displacement relationship, thus, in some ways, they are more difficult to apply in design and practical use than other devices. A typical VED usually consists of flaky viscoelastic materials bonded with steel plates. When relative shear deformation takes place in the viscoelastic materials, the energy caused by dynamic loads is then dissipated. Due to effective energy dissipation capacity from low to high displacement [11], VEDs were used to reduce the structural vibration caused by different kinds of dynamic loads, such as winds, earthquakes and even human activities. The practical projects of VEDs in resisting wind-induced vibration began in the 1960s [12], and the application of VEDs for reducing the seismic responses of civil engineering structures began in the 1990s [13,14]. Recently, VEDs have been recommended to mitigate human-induced vibrations [15]. Additionally, for fire-damaged structures, VEDs are also applied for vibration control [16]. A number of experiments and theories have been improved by scholars such as Shen and Soong [17], Chang et al. [18], Tsai [19] and Xu et al. [20], who have demonstrated that the mechanical properties of VEDs strongly depend on temperature and frequency, thus complicating the analysis and design of structures with the addition of VEDs. Consequently, to effectively simulate the practical application of VEDs, classical rheological models and fractional derivative models are often suggested to describe the VEDs [21–26]. In the frequency domain, Lewandowski and Pawlak [21] combined the widely used response spectrum theory for structures mounted with fractional VEDs. In the time domain, using the generalized Maxwell model and Laguerre polynomial approximation technique, the computation time of dynamic analyses for structures with VEDs is clearly reduced [27]. Therefore, the reasonable model and appropriate theory have been recognized to be effective and feasible for the application of VEDs in practical engineering.