Fundamental considerations for the design of non-linear viscous dampers

Abstract

SUMMARYTwo interrelated issues related to the design of non-linear viscous dampers are considered in this paper: structural velocities and equivalent viscous damping. As the e!ectiveness of non-linear viscous dampers is highly dependent on operating velocities, it is important to have reliable estimates of the true velocity in the device. This should be based on the actual relative structural velocity and not the commonly misused spectral pseudo-velocity. This is because if spectral pseudo-velocities (PSV) are used, they are based on design displacements (S " S ) and are thus fundamentally di!erent from the actual relative structural velocity. This paper examines the di!erence between these two velocities, and based on an extensive study of historical earthquake motions proposes empirical relations that permit the designer to transform the well-known spectral pseudo-velocity to an actual relative structural velocity for use in design. Non-linear static analysis procedures recommended in current guidelines for the design of structural systems with supplement damping devices are based on converting rate-dependent device properties into equivalent viscous damping properties based on an equivalent energy consumption approach. Owing to the non-linear velocity dependence of supplemental devices, an alternative approach for converting energy dissipation into equivalent viscous damping is advanced in this paper that is based upon power consumption considerations. The concept of a normalized damper capacity ( ) is then introduced and a simple design procedure which incorporates power equivalent linear damping based on actual structural velocities is presented.

Computational and rapid expected annual loss estimation methodologies for structures

“…To further address these issues, this study has adopted modified damping approximations proposed by Lin and Chang [21] coupled with the reduction in equivalent viscous damping due to the pinched nature of the real hysteresis curves, as introduced by Pekcan et al [22]. Based on recent studies by Lin and Chang [21], confirmed by Lin et al [23], and modified herein as part of the present study, the damping-related reduction factors, B a , B v , and B d can be calculated as a function of effective damping,  eff as follows: The damping factor for the constant spectral velocity range, B v can be calculated by linear interpolation between B a and B d based on period or spectral displacement.…”

“…Based on recent studies by Lin and Chang [21], confirmed by Lin et al [23], and modified herein as part of the present study, the damping-related reduction factors, B a , B v , and B d can be calculated as a function of effective damping,  eff as follows: The damping factor for the constant spectral velocity range, B v can be calculated by linear interpolation between B a and B d based on period or spectral displacement. Total effective viscous damping,  eff , can be estimated by using the method proposed by Pekcan et al [22]:…”

Spectral analysis and design approach for high force‐to‐volume extrusion damper‐based structural energy dissipation

“…Pekcan et al [7] investigated the seismic performance of a class of dampers conforming to Equation (1). Across a broad spectrum of response, they showed that such …”

“…where 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 F o r P e e r R e v i e w (7)- (9); T = the period of the structure; and T d = the period at the junction of the constant spectral velocity and displacement portions of the spectra. Using Equation (10) accelerationperiod seismic demand spectra for normal soil (where PGA = F v S 1 and F a S s = 2.5F v S 1 ) are presented in Figure 10.…”

Transient Fokker-Planck Equation With SPH Method - Application in Seismic Design

“…The nonlinear viscous force is characterized by the damper exponent α typically ranging from 0.2 to 1 [29] and η the damping coefficient (related to the generalized mass of the system). The excitation is modelled by a white noise W (t) modulated by a time window a(t) defined as…”