Semiactive Damping of Cables with Sag

Abstract

Cables, such as those used in cable-stayed bridges, suspension bridges, guy wires, transmission lines, and flexible space structures, are prone to vibration due to their low inherent damping characteristics. The mitigation of cable vibration is necessary to minimize negative impact. Transversely attached passive viscous dampers have been implemented on some cables to dampen vibration. However, it can be shown that only minimal damping can be added if the damper attachment point is close to the end of the cable. For long cables, passive dampers may provide insufficient supplemental damping to eliminate vibration problems. A recent study by the authors demonstrated that "smart" semiactive damping can provide significantly superior supplemental damping for a cable modeled as a taut string. This article extends the previous work by adding sag, inclination, and axial flexibility to the cable model. The equations of motion are given. A new control-oriented model is developed for cables with sag. Passive, active, and smart (semiactive) dampers are incorporated into the model. Cable response is seen to be reduced by semiactive dampers for a wide range of cable sag and damper location.

Theoretical exploration of a taut cable and a TMD system

“…(14), either ϕ i should be zero, or the damping ratio ξ should approach zero or infinity. Obviously, ϕ i = 0 is not a solution since it cannot satisfy Eq.…”

“…In addition, they pointed out the importance of damper-induced frequency shifts in characterizing the response of the cable-damper system. Johnson et al [14] discussed the performance of a general cable-semiactive damper system. In general, the dynamics for horizontal cable-viscous damper (anchored to deck) systems have been well investigated by previous researchers.…”

Development of a Self-Powered Magnetorheological Damper System for Cable Vibration Control

“…As a more promising solution, semi-active control has been proposed to enhance performance since it offers the capability of active control devices without the requirement of large power resources [2]. In particular, magnetorheological (MR) dampers have attracted extensive attention from In addition, the EMF induced by the generator is proportional to the velocity of the stay cable [32], which implies that both the supply EMF/current and the damping force will increase with the increase in cable vibration.…”

Adaptive Semiactive Cable Vibration Control: A Frequency Domain Perspective

“…However, the passive dampers may potentially lead to insufficient damping to other concerned modes without increasing the damper installation location that may undesirably affect the esthetics of the bridge [12,13], especially for very long cables. Alternative promising solution to cable vibration mitigation is semiactive control based on controllable magnetorheological (MR) dampers due to their real-time adjustable damping effect, fail-safe behavior, and superior energy dissipation over passive dampers [2,6,[14][15][16][17][18][19][20][21][22][23][24][25].…”

“…The optimal control methodology has been adopted in the semiactive cable damping system, based on either the linear quadratic regulator (LQR) control with available full state 2 Shock and Vibration feedback [24,25] or the linear quadratic Gaussian (LQG) control with state observation from noncollocated or collocated measurements [15][16][17][18][19][20][21]. The LQR or LQG control problem is usually treated from a time domain perspective by considering that the cable system model and its associated parameters are known.…”