Semi-active tuned mass damper

SEMI-ACTIVE TUNED MASS DAMPER SYSTEM... 

Most of the above studies have related to the use of dynamic vibration absorbers in mechanical systems. While application ofthese systems in civil engineering structures, frequently known as tuned mass damper (TMD) systems, is expected to be different. In last decades, many research studies have been performed to show the effectiveness of the TMD system and the other control devices, derived from TMD, such as semi-active tuned mass dampers (STMDs) and active tuned mass dampers (ATMDs) in civil engineering community in reducing the structural responses, some of which are reviewed in the following. 

The tuned mass damper (TMD) system is a typical form of control devices including a mass, spring, and a viscous fluid damper, which can be attached to the main structure at one of its degrees offreedom. This system is one ofthe well-accepted devices to control flexible structures, particularly, tall buildings. In this passive control system, if its damping ratio or stiffness of the spring changes with time, then it is called a semi-active tuned mass damper (STMD). 

The equation of motion of the building with a semi active tuned mass damper (STMD) control device is the same as the structure with TMD, but in this case the damping ratio of STMD is a time varying, and can be expressed as which... 

Chey, M. H., Chase, J. G., Mander, J. B., Carr, A. J. (2009). Energy-dissipative semi-active tuned mass damper building systemsfor structural damage reduction. Paper presented at the International Symposium. 

Semi-active tuned mass damper systems. 19 Australasian Conference on Mechanics of Structures and Materials (ACMSM), Christchurch, New Zealand. 

Pinkaew, X, Fujino, Y. (2001). Effectiveness of semi-active tuned mass dampers under harmonic excitation. Engineering Structures, 23(7), 850-856. doi 10.1016/SO141 -0296(00)00091 -2... 

Liedes, T. (2009). Improving the performance of the semi-active tuned mass damper. University of Oulu. Finland Oulu University Press. 

Semi Active Tuned Mass Damper (STMD) In passive TMD system, if its damping ratio or stififiiess of the spring changes with time, then it is... 

Semi-active tuned mass dampers are similar to TMDs, but with the capability of varying then-level of damping. They are mainly used for wind vibration reduction. Another type of semi-active TMD is the semi-active variable stiffness tuned mass damper (SAIVS-TMD), where the stiffness is also controllable. Their performance is similar to that of AMDs but with less power consumption. 

Hrovat, D., Barak, P, Rabins, M. (1983). Semi-active versus passive or active tuned mass damper for structural control. Journal of the Engineering Mechanics Division, 109, 691-705. doi 10.1061/(ASCE)0733-... 

Introducing an additional mass-stiffiiess-damping element at the mass to modify the Eigen frequeneies (Figure 3a). There may be passive masses or active or semi-active systems using e.g. eontrol to accelerate the mass to minimise the deflection of the mass niy Such mass-stifl iess-damping systems are called compensators, absorbers or tuned mass dampers. 

Hybrid control refers either to a combination of passive and active systems or, more commonly, to a combination of passive with semi-active systems, aiming at lowering the forces required by active or semi-active systems, respectively. One such device is the hybrid mass damper (HMD), which combines tuned mass dampers with active actuators. The actuator force is mily used to increase efficiency and robustness to changes in structural dynamic characteristics. Also in the category of hybrid mass dampers is the active-passive composite tuned mass damper (APTMD) developed by Ohrui et al. (1994) and named DUOX. This device is composed of an active mass damper mounted on a timed mass damper. Fig. 8. During structural motion, the mass of the AMD is driven in the opposite direction of the TMD, therefore magnifying the motion of the passive device. When the building... 

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