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Topic: Tuned mass dampers

	Tuned mass dampers
		The assembly in shades of blue at the upper left is an expanding clamp that fixes the root of the TMD flexure beam to the inside diameter of the robot arm tube at its free end with no modifications to the arm itself.
		A key element of the design process was finite element modeling of the TMD alone to identify a suitable geometry and VEM for the constrained layer damper, as well as an analytical design of the damped flexure spring and end mass to obtain the desired natural frequency.
		Various enhancements were subsequently made to the TMD design to improve manufacturability and to allow tuning of the TMD natural frequency in the field.
	www.csaengineering.com /actsys/viscoelasticmaterials.shtml (703 words)

	Reference.com/Encyclopedia/Tuned mass damper
		Typically, the dampers are huge concrete blocks mounted in skyscrapers or other structures, and moved in opposition to the resonant frequency oscillations of the structure by means of springs, fluid or pendulums.
		The presence of a tuned damper forces a comparatively lightweight structure to overcome the inertia of a great mass, such as a giant concrete block, placed in such a way that the mass only begins to move in one direction just as the structure begins to move in the other, thus damping the structure's oscillation.
		At Hockenheim, the mass damper was deemed by the FIA to be a moveable aerodynamic device due to the influence it had on the pitch attitude of the car, and hence, as a consequence, the performance of the aerodynamics.
	www.reference.com /browse/wiki/Tuned_mass_damper (838 words)

	El Dau Laboratory
		Dampers are used in bridges and buildings around the world, especially in areas prone to earthquakes.
		After extensive analysis, the problem was fixed by the retrofitting of 37 fluid-viscous dampers (energy dissipating) to control horizontal movement and 52 tuned mass dampers (inertial) to control vertical movement.
		Tuned mass dampers have been placed in a regular pattern between the underside of the deck and the top of the transverse arms.
	www.vibrodesign.ru /bridge.html (628 words)

	Tuned Absorbers/Dampers
		Tuned absorbers/dampers are reactive devices used in structural and acoustic systems to either absorb oscillation at a certain forcing frequency or damp oscillation at a particular resonant frequency.
		A tuned mass damper (M2, K2, C2) tuned to the resonant frequency of the structure, i.e., 9.5 Hz and a dynamic absorber (M3, K3, C3) tuned to the excitation frequency of 30 Hz are appended to the structure to mitigate its vibration.
		The parameters of a tuned absorber/damper are selected such that their resonant frequencies match the disturbance frequency (for tuned absorption) or resonant frequency of a particular mode (for tuned damping) of an structural/acoustic system being treated.
	www.deicon.com /tuned_abs_damper.html (951 words)

	Tuned mass damper - Wikipedia, the free encyclopedia
		A tuned mass damper, or harmonic absorber, is a device mounted in structures to prevent discomfort, damage or outright structural failure by vibration.
		Tuned mass dampers stabilize against violent motion caused by harmonic vibration.
		The blue line is the motion of m2 in the case with the tuned mass absorber.
	en.wikipedia.org /wiki/Tuned_mass_damper (1280 words)

	WAnews: Page4 (Site not responding. Last check: 2007-10-14)
		Dampers of all kinds, including tuned mass dampers and base isolators, are an emerging technology with application to earthquake and wind induced vibration.
		A tuned mass damper was ruled out for the State Street tower because it would occupy valuable rental space on the top floor.
		A total of 40 viscous dampers were used in the final design with an installed cost of $600,000 or 1.5 percent of the $45 million total renovation cost.
	www.wai.com /Newsletter/Spring96/wanews4.html (773 words)

	:::::: Industrial Environmental Systems, Inc. - Tuned Mass Dampers:::::: (Site not responding. Last check: 2007-10-14)
		The tuned mass damper (TMD) or auxiliary mass damper, is a device consisting of a mass attach
		The mass is attached to the structure by a spring-dashpot system and energy is dissipated by the dashpot as relative motion develops between the mass and the structure.¹
		Tuned Mass Dampers (TMDs) are passive, secondary vibration systems designed to increase the structural dampening of the primary system.
	www.iesysinc.com /tunedmassdampers.htm (367 words)

	Fig 1: Applications of Liquid Dampers
		Tuned Liquid Column Dampers (TLCDs) are a special type of TLDs relying on the motion of a column of liquid in a U-tube like container to counteract the forces acting on the structure.
		However, it is very difficult to tune them to their optimal parameters as the frequency of the damper increases nonlinearly with the amplitude of excitation.
		Mass ratio: is an important parameter, defined as the ratio of mass of the damper to the first modal mass of the structure.
	www.nd.edu /~nathaz/research/liquid/liq_damp.html (2300 words)

	GERB - Applications
		Each TMD is tuned exactly to the structure and a certain natural frequency of it.
		Vertical TMD are typically a combination of coil springs and Viscodampers®, while in case of horizontal and torsional excitation in the corresponding horizontal TMD the coil springs are replaced by leaf springs or pendulum suspensions.
		TMD may be already part of the structure’s original design or may be designed and installed later.
	gerb.com /en/arbeitsgebiete/arbeitsgebiete.php?ID=140&kategorie=15 (329 words)

	the millennium bridge
		Viscous dampers are located under the deck, around the piers and the south landing to control the lateral motions.
		The tuned mass dampers are also located beneath the deck and reduce vertical movements.
		Tuned to a specific frequency these inertial devices, simplistically weights on springs, are attached to discrete points on the structure.
	www.arup.com /millenniumbridge/challenge/solution.html (374 words)

	Seismic Structural Control
		Basically, as lateral movement is introduced, the TMD is provoked and filters the kinetic energy of the vibrations to the viscous damper where it is absorbed.
		A piston transmits the seismic energy to the fluid in the damper, causing the fluid to move inside the damper.
		The MR fluid dampers are comparable to pistons and are attached to chevron braces that are in turn attached to a steel crossbeam.
	mason.gmu.edu /~cpernica/research.html (2202 words)

	oe magazine - Special Focus: On the Table (Site not responding. Last check: 2007-10-14)
		Tuned mass dampers selectively phase cancel the first several natural bending modes of the table structure.
		Tuned dampers (left) concentrate damping where it's needed most—at the frequencies of dominant resonance modes.
		Since broadband dampers (right) are designed to provide moderate damping over a wide range of frequencies, they are not as effective at damping the dominant modes of table vibration.
	oemagazine.com /FromTheMagazine/nov04/onthetable.html (694 words)

	ArchitectureWeek - News - London's Bridge Ascendant - 2002.0410
		The viscous dampers are installed in the central span between the deck and the transverse arms.
		Tuned mass dampers with springs are placed between the underside of the walkway and the steel transverse arms below it.
		A total of 37 viscous dampers and 54 tuned mass dampers were placed across the span.
	www.architectureweek.com /2002/0410/news_3-2.html (510 words)

	GERB - Applications
		Each TMD is tuned exactly to the structure and a certain natural frequency of it.
		Such TMD have been designed and built with an oscillating mass of 40 to 10.000 kg (90 to 22.000 lbs) and natural frequencies from 0.3 to 30 Hz.
		Vertical TMD are typically a combination of coil springs and Viscodampers®, while in case of horizontal and torsional excitation in the corresponding horizontal TMD the coil springs are replaced by leaf springs or pendulum suspensions.
	www.gerb.com /en/arbeitsgebiete/arbeitsgebiete.php?ID=140&kategorie=15 (329 words)

	Tuned mass dampers
		A damper is preferred to reduce resonant response, and an absorber without damping can be used to counter narrowband forced response.
		CSA typically refers to the resonant dampers as tuned mass dampers (TMDs) and to the undamped absorbers as tuned mass absorbers or tuned vibration absorbers (TVAs).
		TVAs and TMDs are modular devices composed of a spring, mass and for TMDs, a damper.
	www.csaengineering.com /vibdamp/tmd.shtml (260 words)

	Pendulum Tuned Mass Dampers for Floor Vibration Control (Site not responding. Last check: 2007-10-14)
		This paper presents the results of the analytical and experimental studies of a pendulum tuned mass damper (PTMD) to control excessive floor vibrations due to human movements.
		Effects of off-tuning of the PTMD due to the variations in the floor mass on its response are investigated.
		Results of the tuning of the PTMD on a laboratory test floor are presented along with the off-tuning effects.
	www.pubs.asce.org /WWWdisplay.cgi?0600467 (236 words)

	The Risks Digest Volume 4: Issue 43
		TUNE MASS DAMPERS STEADY SWAY OF SKYSCRAPERS IN WIND A 50-year-old idea of using the inertia of a heavy floating mass to tame the sway of a tall building is now getting its first real tryout in New York City and Boston skyscrapers.
		A tuned mass damper (TMD) consists of a heavy weight installed near a building's top in such a way that it tends to remain still while the building moves beneath it and in away that it can transmit this inertia to the building's frame, thereby reducing the building's motion.
		To the engineers who designed it, the TMD is a positive approach to relieving wind-induced building motion because it counteracts motion rather than first receiving it and then deadening it, which is the inefficient and more costly result of substantially increasing mass or stiffness.
	catless.ncl.ac.uk /Risks/4.43.html (2096 words)

	[No title]
		The current mass damper systems are cumbersome, take up lots of space, are difficult to install, and are potentially dangerous (according to Kwok).
		The use of tuned mass dampers is not new.
		The Chifley Tower Tuned Mass Damper is the heaviest in the world (400 tonnes) and is the first of its kind used in Australia.
	www.abc.net.au /quantum/info/q95-18-4.htm (546 words)

	COWI publications - publikationer: Tuned Mass Dampers for a suspended structure of footbridges and meeting boxes
		Tuned Mass Dampers for a suspended structure of footbridges and meeting boxes
		Tuned Mass Dampers (TMD) were therefore designed to mitigate these vibrations.
		At the final stage of construction, the response of the structure was measured for one person walking across the footbridge at the identified critical pace rates.
	www.cowi.dk /cowi/da/publikationpopup/?guid={EEA4EDB0-08F5-4F7B-82F8-CD8B33145F1E} (179 words)

	1997 Building Publications - Method of Estimating the Parameters of Tuned Mass Dampers for Seismic Applications. (Site not responding. Last check: 2007-10-14)
		The optimum parameters of tuned mass dampers (TMD) that result in considerable reduction in the response of structures to seismic loading are presented.
		The criterion used to obtain the optimum parameters is to select, for a given mass ratio, the frequency (tuning) and damping ratios that would result in equal and larger modal damping in the first two modes of vibration.
		The parameters are used to compute the response of several single and multi-degree-of-freedom structures with TMDs to different earthquake excitations.
	fire.nist.gov /bfrlpubs/build97/art049.html (217 words)

	Seismic retrofit - Wikipedia, the free encyclopedia
		Dampers absorb the energy of motion and convert it to heat, thus "damping" resonant effects in structures that are rigidly attached to the ground.
		Tuned mass dampers employ movable weights with dampers.
		A solution to this problem is to include at some upper story a large mass, constrained, but free to move within a limited range, and moving on some sort of bearing system such as an air cushion or hydraulic film.
	en.wikipedia.org /wiki/Seismic_retrofit (6097 words)

	Roush Damping Products – damping adhesives, rubber materials, tuned mass dampers – Noise and Vibration ...
		Rubber materials can be produced to customer specifications from hundreds of formulations for use in devices like isolators, tuned mass dampers, damping links, and acoustic gaskets.
		Tuned mass damping is an extremely effective method of reducing resonant vibration.
		Using our customized optimization software, which interfaces directly with an extensive library of viscoelastic materials, we are able to achieve the desired noise and vibration attenuation characteristics for specific product and customer needs.
	www.roushind.com /html/nvh_nvcpdamping.htm (259 words)

	Active Multiple Tuned Mass Dampers: A New Control Strategy (Site not responding. Last check: 2007-10-14)
		Active multiple tuned mass dampers (AMTMD) consisting of many active tuned mass dampers (ATMDs) with uniform distribution of natural frequencies have been, for the first time here, proposed to attenuate undesirable oscillations of structures under the ground acceleration.
		In light of the physical principle of the passive MTMD, the active control forces of AMTMD are defined, namely, the control forces are generated through keeping the identical displacement and velocity feedback gain and varying the acceleration feedback gain.
		With resorting to the criterion, the research is conducted on the parameters reflecting the effectiveness and robustness of AMTMD.
	www.pubs.asce.org /WWWdisplay.cgi?0302352 (381 words)

	TRB Research in Progress > Browse Projects > Detailed View
		This is a follow-on activity for a recently complete IDEA project (NCHRP-50) to perform a full-scale trial to demonstrate the effectiveness of tuned mass dampers (TMD) in minimizing stay cable vibrations on a bridge in Mobile, Alabama.
		In the second stage, the full-scale TMD system will be fabricated and subjected to a series of laboratory tests to determine its basic static and dynamic characteristics.
		Following necessary refinements, the TMD prototype will be installed on a selected number of cables on the Cochrane Bridge in Mobile, Alabama, and the cables will be monitored for vibration damping for several months.
	rip.trb.org /browse/dproject.asp?n=5238 (264 words)

	One Wall Centre Project :: The Glotman Simpson Group Consulting Engineers
		Two tuned liquid column dampers (TLCDs), each consisting of a four-storey high, 50,000-gallon water tank, extending nearly the full width of the tower, were placed at the top of the 48-storey building.
		The dampers work by allowing the water to move back and forth along the bottom chamber of the tank and up into the columns.
		The liquid column dampers had to be tuned exactly because once the tank walls had been constructed only the water volume and a gate through which the water flows could be changed to adjust the vibration characteristics.
	www.glotmansimpson.com /projects/onewallcentre/wallcentre.htm (1139 words)

	MULTI-FREQUENCY EARTHQUAKE / WIND QUIETING BUILDING SYSTEM
		, 1994, it represents a more sophisticated structural control technique in which each individual mass damper is substituted with a mass damping floor diaphragm substructure consisting of a multitude of differently tuned mass dampers.
		Being tuned, with the help of their geometry and material properties, to the main natural frequencies of the building, the
		When swaying of a building begins, one or several beams gets involved in a vigorous resonant vibration which absorbs the propagating energy of the major resonant waves in the building structure thus preventing lateral displacement amplifications in the building structure during an earthquake or wind.
	www.ecs.csun.edu /~shustov/Topic9.htm (432 words)

	Multitech Vibration Dampers
		Liquid Dampers Mass Dampers Frequenty Asked Questions Vortex Shedding Helical Strakes Case Studies
		Meca is the exclusive representative for Multitech dampers in the US and Canada.
		Based upon a given situation, we can recommend a damper which offers the best technical and economical solution to a problem.
	www.mecaenterprises.com /dampers.htm (127 words)

	HKUST Institutional Repository: Item 1783.1/2079
		A preliminary strategy of using multiple tuned mass damper (MTMD) system on buffeting control of the Yangpu Bridge are presented in this paper.
		The MTMD system consists of a set of TMDs which are attached to the center region of the bridge's main span and are symmetrical about the center of the main span as well as about the central line along the bridge span.
		A level-type of TMD has been proposed which requi[r]es less space for installation as compared to the traditional hanging type of TMD.
	hdl.handle.net /1783.1/2079 (219 words)

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