London Millennium bridge was modelled in this thesis in order to show the effect of tuned mass damper. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media. Since the seal element elastically flexes rather than slides, seal hysteresis is nearly zero. Contact us today for more information. When opened in 2000, it was found that low-frequency lateral vibrations were excited by pedestrians. Dampers on the Millennium Bridge in London. Dampers are used in bridges and buildings around the world, especially in areas prone to earthquakes. A total of 37 viscous dampers are to be installed, the majority of which are to be situated beneath the bridge deck, on top of the transverse arms, every 16 m. Each end of the viscous damper is connected to the apex of a steel V-brace, known as a chevron. It is owned and maintained by Bridge House Estates, a charitable trust overseen by the City of London Corporation. The Millennium Bridge is a footbridge across the River Thames in London. Millennium Bridge is a suspension bridge, pedestrian bridge (footbridge) and steel bridge that was built from 1996 until 2000. I believe that 109 and 2 x 109; should be 2E109 cycles. The white disk is not part of the damper. For a while, some even regretted that the 70-millimetre (2.8-inch) sideways sway was quickly fixed with the invisible application of shock absorbers and tuned mass dampers. The damper must respond to tiny deflections as low as 0.025 mm with high resolution, otherwise the suppression of feedback would not be possible until the bridge was already well into resonance. Millennium Bridge cables / Source 6. • 700-ton steel/aluminum The tests proved to be anticlimactic—the bridge behavior being generally described as “rock solid” by the crowd. attaching additional dampers to the structure. This type of seal does not slide, but rather flexes without hysteresis as the damper moves. The bridge is an unusually shallow stressed cable suspension bridge, specifically designed to provide… The volume displaced by the compressing bellows passes through the crossover ports to the extending bellows at the opposite end of the damper. The second benefit of dampers is that most of them would be beneath or within the structure and therefore generally hidden from public view. All dampers were fabricated and delivered to the bridge site in 2001, and testing of the structure with groups of pedestrians began in January 2002. This included 37 energy dissipating dampers to control the horizontal movement and 52 inertial dampers to control the If you . To assure a high resolution output, all damper attachment clevises were fabricated with fitted spherical bearings and fitted mounting pins, such that zero net end play existed in the attachment brackets. The most unique element of this design is a frictionless seal made from a welded metal bellows. The Millennium Bridge, officially known as the London Millennium Footbridge, is a steel suspension bridge for pedestrians crossing the River Thames in London, linking Bankside with the City of London. Millennium bridge by Foster + Partners The Millennium bridge by Foster + Partners springs from a creative collaboration between architecture, art and engineering. DAMPER DESIGN What was unique about the Millennium Bridge was that resonance was occurring without any expected forced motion or marching. (upstream). In 2001, Taylor Devices Inc. developed special Viscous Dampers for use on the Millennium Bridge in London, England. Adapting this basic design to the Millennium Bridge involved simply scaling the small satellite dampers to the required size range. The most promising were: Stiffening the bridge, limiting the allowable number of people allowed on the bridge, active control, or supplemental passive damping. Millennium Bridge The design of a new pedestrian bridge across the River Thames, between Bankside and St Pauls. The London Millennium Footbridge has an unusual low-slung suspension design, supported by steel cables anchored to piers on the opposite river banks. It is the newest bridge across the Thames. The Millennium Footbridge was ope ned to the public on June 10, 2000 B the first new bridge across the River Thames in historic London in more than a century. A Cambridge University Engineering Department account of the Millennium Bridge problem. The Millennium Bridge has reopened to the public, after a £5m repair programme. How big is the Millennium Bridge? A total of 37 dampers were constructed, of 7 different types. It consists of 3 separate parts, one being 81 meters (266 feet) long, another being 144 meters (472 feet), and the final part being 108 meters (354 feet) long. The design was chosen through open competition and was won by Foster & Partners and Sir Anthony Caro with Arup. This requirement became even more difficult when taken in context with the extremely long cyclic life; conventional hydraulic practice is to use seals with heavy interference for long life under dynamic cycling. The £18.2m bridge swayed under the weight of thousands of pedestrians when it first opened in June 2000. Thus, if a simple first order system with 0.5% critical damping is excited by forced resonance, the magnification factor is: If damping in the system is elevated to 20% critical, then the magnification substantially reduces to: The damping devices used on the bridge resulted in five major design issues, some of which are unique to this particular structure. To reduce the amplitude of these swaying oscillations, modifications were made in two ways. Masses of people walking up and down stairs at once, or great numbers of people stomping in unison, can cause serious problems in large structures like stadiums if those structures lack damping measures. These dampers were specified and designed to be used for mitigating the dynamic response of the bridge due to pedestrian traffic. Top global problem solving EE forum covering Microcontrollers, DSP, Networking, Analog and Digital Design, RF, Power Electronics, PCB Routing and much more, The Engineering Exchange is a global educational networking community for engineers.Connect, share, and learn today », Copyright © 2021 WTWH Media, LLC. This would create a direct link between the north and south side of the river, and encourage the revival of a long-neglected area of London. The Millennium Bridge was retrofitted with an additional 89 dampers to reduce the wobble to a safe level. All parts, including the metal bellows, were designed with low stress levels to provide an endurance life in excess of 2 x 109 cycles. For a simple spring-mass-damper system, amplitude under steady-state forced resonance is: where X = Resonant amplitude The operators, the Millennium Bridge Trust, Southwark council and the Corporation of London, said the move represented "a significant step towards the … The dampers must continuously cycle at an average frequency of 0.8 Hz. Taylor Devices, a manufacturer of damping products, proposed a unique solution, a damper that was previously used exclusively by NASA and other U.S. Government agencies for space-based optical systems. The Millennium Bridge reopened in 2002 after engineers fitted it with 91 dampers to absorb both lateral and vertical oscillations. 座標: 北緯51度30分37秒 西経0度05分54秒 / 北緯51.510173度 西経0.098438639度 / 51.510173; -0.098438639, ロンドン・ミレニアム歩道橋(London Millennium Footbridge)はミレニアム橋の愛称で親しまれている、ロンドンのテムズ川にかかる歩道橋。2000年6月に完成した。, 歩道橋はイギリスのミレニアムプロジェクト(2000年記念事業)[注 1]のひとつとして1996年にサザーク議会によるコンペの結果、アラップ、フォスター・アンド・パートナーズ、アンソニー・カロによる設計案が当選した。, 建設は1998年後半に起工、歩道橋部分は1999年4月28日に着工した[1]。建設費は1820万ポンドで、ミレニアム委員会とロンドン信託により支払った[2]。2000年6月10日に開通したものの大きな横揺れの発生により2日後に閉鎖、対策工事を経て2002年2月22日に再開通となった。, 同歩道橋はサザーク橋(下流)とブラックフライアーズ鉄道橋(上流)との間に位置しており、南側には、グローブ座、バンク・サイド・ギャラリー、テート・モダン、北側にはセント・ポール大聖堂がある。最寄りのロンドン地下鉄の駅は、マンション・ハウス駅である。, 2000年6月10日の開通当日は、橋に隣接するテート・モダンの人気も手伝い大勢の歩行者が訪れた。しかし、人々が橋を歩き始めると、橋は小刻みに大きな横揺れを始めた。開通日の午後以降は通行人数を制限する対応がとられたが、6月12日に対策工事を行うため一時閉鎖となった。, この橋は幅の狭い吊り橋であり、多少の揺れは予測されていた。また開通日は風の強い日だった。しかし、これらを勘案しても実際に生じた揺れは想定を上回る大きなものだった。調査の結果、次のような原因で揺れが生じたことが判明した。まず、人間は人混みを歩くときに他人との衝突を避けるために無意識に他人の歩調に合わせる心理があり、歩行による荷重は分散せずに周期的なものとなった。そして橋の固有振動周期が荷重の周期に近かったため、共振により揺れ始めた。さらに、ひとたび橋が揺れ始めると、多くの歩行者が揺れに対応しようとして橋の振動に歩調を合わせるようになり、ますます橋の揺れが激しくなった[3]。, 対策として、橋の振動数を制御して共振を起こりにくくするためにダンパーを追加する工事を行った[3]。補修工事には500万ポンドを要し[3]、2002年2月22日に再開通した。, Millennium Commission(千年紀組織委員会)が主導して多くの記念イベントの開催や記念建造物が造られている。事業費用の一部はナショナル・ロッタリー(, Life: The Observer Magazine - A celebration of 500 years of British Art - 19th March 2000, Brooklyn Bridge: lateral S-shaped vibration = pedestrian oscillations or "sway". Ideally, the damper should be maintenance free for the entire life cycle. Detail of dampers added to Millennium Bridge to prevent wobble Piano mechanism - hammers, felts, action, dampers of Steinway upright piano, 1909 Internal dampers of a piano Dynamite Blasting under Water. • 12 ft wide suspension deck with no support towers, uses lateral cables for support. Browse the most current issue of Design World and back issues in an easy to use high quality format. Millennium Bridge was London’s first new pedestrian bridge for over a century. We also share information about your use of our site with our social media, advertising and analytics partners who may combine it with other information that you’ve provided to them or that they’ve collected from your use of their services. www.taylordevices.com. The damper response must have low hysteretic content to avoid pedestrians sensing the classical “stick-slip” motion of a conventional sliding contact fluid seal, with the resultant perception of instability in the bridge structure. Nearly 100,000 people used it in its first day of operation. ミレニアム・ブリッジの閉鎖中尾政之、失敗知識データベース Millennium Bridge - Structurae Arup's Millennium Bridge site A PDF paper from Arup, discussing the engineering and resonance of the bridge. The modifications involved the installation of a series of dampers designed to reduce the movement of the bridge to acceptable levels. These high interferences in turn generate high seal friction, accentuating the “stick-slip” motion. Several major design issues for the dampers were noted by the bridge design team, and all of these needed to be satisfied before added damping could be considered as a viable solution. No observable biodynamic feedback occurred. Here’s How, How and Why You Should Use a Wave Spring for Bearing Preload. More importantly to the engineering team, the damped bridge structure performed superbly: Taylor Devices Inc. The bridge has a total length of 325 meters (1,066 feet) and because it’s a pedestrian bridge, it’s only about 4 meters (13 feet) wide. Several distinct designs of dampers were required, each of which had different output forces, deflections, component equations, and envelope dimensions. All Rights Reserved. These previous applications had similar requirements for long life and high resolution at low amplitudes, but required relatively low damper forces from small, lightweight design envelopes. After just three days the bridge's operators had to close the 320-metre long structure, which crosses the River Thames between St Paul's Cathedral and the Tate Modern. (upstream). the Millennium Bridge. The white disk is not part of the damper. Because hydrodynamic bushings are used, no sliding contact with the piston rod occurs, assuring frictionless performance. The bridge remained closed for almost two years while dampers were installed. The majority of cycles would take place at low amplitude, but the total number of cycles required by the owner was based on a 50 year bridge life. The project is located in City of London and Southwark, London, England, United Kingdom. X0 = Zero frequency deflection of the spring-mass system under the action of a steady force Nearly 100,000 people used the new bridge in its first day of opera tion. The Millennium Bridge is a footbridge across the River Thames in London.It is a steel suspension bridge which links Bankside with the City.Its position is between Southwark Bridge (downstream) and Blackfriars Railway Bridge (upstream). Damping was eventually chosen as the preferred solution. In February 2001, the Millennium Bridge Trust announced that it had raised the 5 million needed to carry out the recommended modifications to the bridge and the remedial work started in May 2001. You consent to our cookies if you continue to use this website. It is a steel suspension bridge which links Bankside with the City. Millennium Bridge Facts: • Pedestrian bridge, 1090 ft. length, crosses the Thames River in downtown London, England. Metal bellows dampers from Taylor Devices are designed for low displacements and offer an infinite lifespan. Its position is between Southwark Bridge (downstream) and Blackfriars Railway Bridge (upstream). The project team evaluated numerous concepts that would reduce or eliminate the feedback response. Adapting this basic design to the Millennium Bridge involved simply scaling the small satellite dampers to the required size range. While this is occurring, damping forces are produced by orifices in the damping head, and the pressures generated are kept isolated from the metal bellows by high restriction hydrodynamic labyrinth bushings. Clip, share and download with the leading design engineering magazine today. These dampers were specified and These dampers were specified and designed to be used for mitigating the dynamic response of the bridge due to pedestrian Firmly positioned in the 'A list' of London attractions, the Millennium Bridge is a 330m steel bridge linking the City of London at St. Paul's Cathedral with the Tate Modern Gallery at Bankside. Developed with sculptor Anthony Caro and engineers Arup, the commission resulted from an international competition. The Millennium Bridge, officially known as the London Millennium Footbridge, is a steel suspension bridge for pedestrians crossing the River Thames in London, England, linking Bankside with the City.It is located between Southwark Bridge (downstream) and Blackfriars Railway Bridge (upstream). The design concept was based on the premise that added damping would reduce resonant deflections to a suitably low level. Seemingly random pedestrian footfalls were causing resonance of the bridge deck, with lateral accelerations measuring up to 0.25 g. The phenomena of forced harmonic excitation of bridge structures is well understood, and has been well documented by many sources. https://ja.wikipedia.org/w/index.php?title=ミレニアム・ブリッジ_(ロンドン)&oldid=80726445. In the case of London’s Millennium Bridge, both these conditions applied. The bridge opened on 10 June 2000. The metal bellows and other moving parts were constructed from stainless steel for corrosion resistance. This equates to more than 109 cycles of life, far in excess of normal values for any sort of conventional damping device. This issue was compounded by the fact that due to wind, thermal, and static loadings, total damper deflections of up to plus or minus 275 mm were required. When the Millennium Footbridge opened to the public on June 10, 2000, it was the first new bridge across the River Thames in historic London in more than a century. The Millennium Bridge has a uniquely thin profile Dampers reduced the dynamic response by at least 40 to 1 for all modes. δ = Critical damping factor, = By definition, the magnification factor of the resonant response. We use cookies to personalize content and ads, to provide social media features and to analyze our traffic. Peak measured accelerations reduced from 0.25 g undamped to 0.006 g damped. As the damper moves, the two bellows alternately extend and retract by flexure of the individual bellows segments. Just before the Millennium Bridge in London was re-opened,18 months after it closed due to excessive wobbling. Damper frequency response requirements were defined as D.C.B2 Hz with a high fidelity output over this entire bandwidth. The London Millennium Footbridge across the River Thames, for example, opened with great fanfare in 2000, only to close within days after large crowds found the bridge rocking unnervingly as they walked. The most direct application to the problem used supplemental viscous damping devices to elevate total structural damping levels to the 20% critical range, compared to approximately 0.5% critical damping for the as-built structure. People-excited lateral bridge vibration is likely to occur for pedestrian bridges which have low natural frequencies of swaying movement (less than 3 Hz) and for which the lateral modes have light damping. Configuration Management: Configuration Integrity IS A Core Driver for Business Success, Create your perfect machine with Advanced Engineering, How a ME/EE turned passion for design into his own bike company, Everyone Can Save on Cable Costs. As this University of Cambridge article on the design states, "as a result [of the added 37 linear viscous dampers and over 50 tuned mass vibration absorbers] this bridge is now probably the most complex passively-damped structure in the world. All parts, including the metal bellows, were designed with low stress levels to provide an endurance life in excess of 2 x 109 cycles. But a mere two days later, it was ordered closed due to hazardous deck motions. The London Millennium Bridge had this happen back in 2000, (check out the video below); after this incident dampers were added to the bridge. After extensive review of available video footage during the period the bridge was open, a series of tests identified a unique biodynamic feedback phenomena, “synchronous lateral footfall,” which resulted in seemingly random walking motions becoming synchronized over time among members of an unrelated group of people on the bridge. On June 12, 2000, the Millennium … The dampers are located outdoors, over a brackish waterway with tidal flows. The lateral damping for the Millennium Bridge is provided primarily by fluid viscous dampers. The design life was such that all major operating elements of the dampers needed to be constructed from inherently corrosion resistant metals that would not degrade over time. Two metal bellows seals are used to seal fluid in the damper. Testing consisted of well-regulated crossings on the bridge by the entire crowd at different walking speeds. Site Map | Privacy Policy | RSS. The modifications cost about $8.9 million. Millennium Bridge in London, United Kingdom. Crossings on the premise that added damping would reduce or eliminate the feedback response for modes! Of thousands of pedestrians when it first opened in 2000, it was found that low-frequency lateral vibrations were by. Movement and 52 inertial dampers to reduce the amplitude of these swaying oscillations, modifications were made in ways. Was ordered closed due to hazardous deck motions footbridge ) and steel that... Bridge reopened in 2002 after engineers fitted it with 91 dampers to absorb lateral... 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