Mass-Spring System - Railway Pro

2Highly EffectiveStructure-Borne Noise ProtectionEffectiveover decadestructure-borne sound emissionsScan be reduced at their point oforigin through various measurestailored to the specific requirements.Mass-spring systems are used insituations where the highest demandsare placed on structure-borne soundprotection. The materials Sylomer® andSylodyn® are used throughout theworld as individual, elastic supports.They guarantee the required effectivenessfor decades. Combined withGetzner’s technical know-how, theseproven materials are now consideredto be the standard high-tech solutionfor mass-spring systems.4

Advantages ofSylomer® and Sylodyn® supports— Reliable, homogenous and lasting elasticitySylomer® and Sylodyn® are the idealmaterials for use as highly elasticsupports in a mass-spring system –whatever the construction method.— Short-term, even extreme, overloading is possible— Can be directly driven over by heavy vehicles— Low construction costs thanks to simple and fast installation— Various shapes are possible by varying the density, thicknessand loaded area of the material— High efficiency and long-term stability— Minimal maintenance expenses5

3How a Mass-Spring SystemFunctionsEffectively isolatingvibrationsThe goal of vibration isolation is todynamically decouple the superstructurefrom its environment in order toreduce the transmission of vibrationsand structure-borne sound.This decoupling is achieved by creatinga system capable of vibration. Ifa permanently elastic spring layer, suchas Sylomer® or Sylodyn®, is installed,the isolation takes place directly at thesource of the emissions. This ensuresthat the support point force F u(t) issmaller than the exciter force F e(t), resultingin reduced vibrations producedby the support point forces.mcF e(t)dF u(t)The function of an elasticallysupported superstructure can bedescribed very easily using an alternatesystem, referred to as a singledegree of freedom system. Manyvibration problems can be approximatelyexplained with this simplephysical model. If the superstructuremass is brought out of equilibrium bya brief exciter force F e(t), the massexecutes vibrations with the naturalfrequency f 0.c = dynamic spring stiffnessm = superstructure mass +unsprung mass of wheelset6

The speed with which these vibrationsdecrease in amplitude dependson the damping of the spring.For Sylomer® and Sylodyn® materials,the damping is described by themechanical loss factor.The amplitude frequency response(amount of transmission function) mustbe determined in order to evaluate amass-spring system. This describes theamplitude relationship based on thefrequency f or based on the frequencyrelationship between the support pointforce F u(t) and the exciter force F e(t) inthe case of source isolation.Load transmission factor V R3.02.52.00.10.20 00.3Two areas exist in the vibrationisolation system, specifically anamplification area and an isolationarea.The amplification only occurs if anexciter frequency is present thatmatches the natural frequency of theelastic support or in the case ofbroadband stimulation.The isolation starts at a frequency thatcorresponds to 2•f 0. The amplitudefrequency response indicates that theamplification at the insulator naturalfrequency f 0is reduced with an increasinglevel of damping, while the level ofisolation decreases with increasingdamping.In terms of the properties of the springin a mass-spring system, this meansthat the system must have the lowestpossible ratio of dynamic to staticstiffness. The dynamic stiffness of thesupport should also only be subject tominor changes due to frequency andload.The dimensioning of a mass-springsystem is an optimization problem forengineers. This problem requiresin-depth and specialized knowledge,such as that which Getzner has offeredwith its partners for years. The functioningof a mass-spring system can,however, be greatly affected by standingwater under the mass trough andwithin the system. When installing amass-spring system, it is thereforeessential to ensure sufficient long-termdrainage.1.50.50.81.0=1.00.80.3 0.50.50.20.10.00.3 0.4 0.6 0.8 1 2 2 3 4 5 6 7 8Tuning ratioAmplificationIsolation7

4DesignVariantsA number of different designs havebeen developed by European railwaycompanies for mass-spring systems inrecent decades. For instance, thereare designs with either in-situ castedor prefabricated concrete slabs aswell as combinations of the two, bothwith and without ballast beds.In designing an elastic support formass-spring systems, the selectedconstruction method is also importantfor the functionality and economicefficiency of the overall system.Whether full-surface, linear or pointlikesupport – Getzner’s know-howensures technically faultless, economicallysustainable and functionalsolutions.8

Full-surface support Linear support Point-like supportFull-surfacesupportDepending on the specific application,a full-surface elastic supportachieves natural frequencies in therange of 14-25 Hz. This corresponds toan achievable structure-borne noisedamping of up to 30 dB in the supercriticalfrequency range.A full-surface elastic support fromGetzner offers advantages in thefollowing areas:— Simple, fast and inexpensive constructionmethods— Low risk of construction errors— Wide-area load distribution in thesubsoil— Damping of structural vibrations ofthe track support elements— Low number of installation joints— High horizontal stability of the entiresystem— Economy of the entire systemLinearsupportLinear supports are preferred inmass-spring systems that make useof prefabricated elements or combineprefab with in-situ casted concrete. Thehorizontal forces that arise both in thedirection of travel (braking and accelerationforces) as well as perpendicularto the track axis (e.g. centrifugal forces,side forces resulting from track geometryerrors) can be handled well by therelatively large support surfaces.With linear support, it is possible toachieve lower support structurenatural frequencies (8-15 Hz) than withfull-surface support while keepingexpenses reasonable. Overall, linearsupport achieves a higher damping ofstructure-borne sound.Point-likesupportThe selected construction methodfor the track support slabs or tracktroughs determines the type ofpoint-like support. Generally it is usedwith track support slabs created usingsite-mixed concrete and lifted intoplace after hardening. The supportsare inserted through openings in theplate.Since train operations give rise tohorizontal forces, attention must bepaid to the transmission of these forcesduring dimensioning of the generallyrelatively small support surfaces. Inorder to limit the horizontal deflectionsin line with the requirements, theoptimal values for shear modulus,support layer thickness and supportarea are used in practice.The lowest natural frequencies areachievable with point-like supports(5-12 Hz). This type of support satisfiesthe highest requirements forstructure-borne sound protection.Structure-borne sound damping of30 dB and more can be achieved withthis type of system.9

6ConstructionErrorsOur experiencegives you securityConstruction or design errors andimproper or absent features can insome cases affect the real propertiesof mass-spring systems.Examples include:— Insufficient or absent drainage resulting in a “stamp effect”within the system— For full-surface systems: absent, unsuitable or excessively stiffside mats— Faulty isolation of cable shafts, drainage inlets and otherconnections— Unsuitable support material or support layer thicknesses belowspecific minimums— Large number of installation joints— Improper, careless installation of the support material— Structural design, such as the length of the deck slab or designof the reinforcement, insufficient load distribution on theelastomerExecution flaws in a mass-springsystem can generally only becorrected later at great expense andeffort. Depending on the severity of theflaws, it is sometimes necessary tocompletely rebuild the track.12

7Requirements for anElastomer SupportMulti-facetedand provenFor more than four decades, thematerials Sylomer® and Sylodyn®have proven themselves to be effectiveprotection against vibrations andstructure-borne sound in railwaysuperstructures.Getzner materials contribute to theprotection of structures, improve thestability of railway tracks and reducethe dynamic load on the ballast,thereby lowering maintenance expensesas well. Even after 30 years or more,railway applications made of Sylomer®and Sylodyn® remain effective. Whensamples were removed and tested, theelastomer showed no fatigue evenafter many years of operation.For less than full-surface support, it isparticularly important to define therequirements for the support materialand the quality monitoring on aproject-specific basis.The standard DIN 45673-7, Mechanicalvibration – Resilient elementsused in railway tracks – Part 7: Laboratorytest procedures for resilientelements of mass-spring-systems,provides additional information onsuitability for use and testing of thestatic-dynamic stiffnesses.Conditions for functioning and long-lasting massspringsystems:— The static and dynamic stiffnesses must be evaluated in order todetermine the specifically required properties of the support.— Changes to the specific support properties due to operating loadsare tested with long-term vibration tests consisting of at least threemillion load changes.— Changes to the support properties due to environmental influences(e.g. ozone, water, oils, chemicals) must also be evaluated.— Further tests determine the extent to which the track geometrychanges due to creeping, operating loads and environmentalinfluences.— The quality of the support is carefully monitored even beforeinstallation.13

8Finite ElementAnalysis14

Finite element analysis yieldsthe following results:— Support capacity of the support slab— Static deformation due to deadweight— Natural modes— Natural frequencies— Strength information— Dynamic loading and vibrationmovements— System behavior under definedstimulation— Prediction of the dynamic behaviorof a system for various systemparametersKnow what you aredealing withsubstitute physical system consisting of mass relationships,stiffnesses and damping coefficients must alwaysAbe developed for a system analysis. The most well-knownsystem analysis method is finite element analysis (FEA).In vibration isolation, it is generally assumed that the vibration-isolatedobject (the support slab of the track) and thesubsoil are each rigid bodies. The purpose of this assumptionis to verify the effect of the vibration isolation by way ofsimulation. However, if one wishes to identify limitations andunderstand the total behavior of the system, additionaldegrees of freedom that are relevant to the real system areidentified and analyzed using FEA.The design requirements are constantly growing. Getzneroffers a wide range of services as a competent partner toplanners and engineers working on this complex subject.— Required modifications for a desireddynamic behavior15

9InstallationInformation16

Isolation of a mass-spring systemagainst drainsPreparatorymeasuresWhen installing, it is important toensure that the Sylomer® orSylodyn® support layer completelydecouples the subsequently laidsupport slab from the environment.Sound bridges can prevent functionalvibration isolation. It is also importantto ensure drainage of the system.The subsoil must therefore be flat andfree of pointed or sharp objects. If thisis only possible to a limited extent, it ispossible, for example, to lay a fleecebetween the subsoil and the mat toprotect the support layer. A sub-baseof concrete has also proven effective.Special discrete bearings must bestable and accurately positioned. Acorresponding base with a steel framerepresents one effective option.Reinforcement may be useful for afull-surface solution. In this case,sufficient load distribution from thereinforcement to the Sylomer® orSylodyn® mats must be ensured.Corresponding supporting surfaces(wood or plastic panels) preventexcessive surface compression ordeflections.DeliveryGetzner delivers the materialsdirectly to the construction site:side mats, linear supports and discretesupports on pallets, ground mats asrolled sheets with a standard width of1.50 m. Depending on the geometryand installation conditions, Getznerassembles the mats already at thefactory, allowing fast and economicalinstallation on-site.The ground mats can be laid bothparallel and perpendicular to the trackaxis. It is important here to keep thenumber of joints as low as possible.The remaining joints are sealed withtape to prevent the concrete mixturefrom entering and creating structurebornesound bridges.LayingGetzner always pays attention tothe total weight when assemblingthe rolls. This means that the mats caneasily be laid by a two-man team. Inthis way, it is possible to lay over500 m 2 per person each day. Linearand discrete supports can even bepositioned by a single person. The matlength or protruding corners can beeasily corrected by the person layingthe mats using disposable knives.If desired, Getzner will create professionalinstallation plans or provide aconstruction supervisor to guaranteeproper installation.17

10InternationalReferencesTokyo rapid transitGetzner solutions can be foundaround the world – as can Getznerexperts. With our five branch offices, wehave a local presence in important geographicregions. We service practicallyall of the relevant markets in the worldwith our numerous sales partners.Branches in:— Bürs, Austria— Berlin, Germany— Grünwald near Munich, Germany— Amman, Jordan— Tokyo, Japan— Pune, India— Beijing, ChinaSales partners in:— Argentina— Australia— Belgium— Brazil— China— Czech Republic— Denmark— Egypt— Finland— France— Great Britain— Greece— Hungary— India— Iraq— Italy— Japan— Jordan— Lebanon— Netherlands— Norway— Palestine— Portugal— Romania— Saudi Arabia— Singapore— Slovenia— South Korea— Spain— Sweden— Switzerland— Syria— Taiwan— Turkey— USA18

Milan tram line Nottingham tram line Munich underground lineProjects realized by Getznerspeak for themselves. Here isa sampling of our reference list inthe railway sector:Getzner branch officesReference countriesStandard-gauge railwaySelect projects:— Brenner rail axis,northern approach lineBrenner Zulauf Nord,Römerberg Tunnel,Zammer Tunnel,Arlberg Tunnel,New Lainz Tunnel,Sittenberg Tunnel (ÖBB)— Leipzig City TunnelOld Mainz TunnelNew Mainz TunnelCity Tunnel Leipzig,Alter Mainzer Tunnel,Neuer Mainzer Tunnel,Tiergarten Tunnel,Berlin North-South,Lehrter Bahnhof (train station),Amperbrücke (bridge),Cologne/Bonn airport connection,Siegauen Tunnel,Audi Tunnel Ingolstadt (DB AG)— NEAT: Zurichberg Tunnel,Zimmerberg Tunnel (SBB)— Rome-Fiumicino,Udine-Tarvisio,Milan-Saronno,Catania (FS)— Channel Tunnel Rail Link(Network Rail)— Brussels (SNCB)Tram lines— Augsburg— Barcelona— Berlin— Bern— Bordeaux— Brest— Constantine— Essen— Florence— Geneva— Gothenburg— Graz— Grenoble— Isfahan— Le Mans— Linz— Lyon— Madrid— Marseille— MashhadUnderground/rapid transit lines— Athens— Augsburg— Berlin— Bochum— Buenos Aires— Dortmund— Düsseldorf— Hong Kong— Incheon— Milan— Montpellier— Munich— Nantes— Nice— Nottingham— Orléans— Paris - St. Denis— Paris - T1— Prague— Rome— Rouen— Santo Domingo— Seville— Shiraz— Strasbourg— Stuttgart— Tenerife— Valencia— Vienna— Krakow— Milan— Munich— New York— Nuremberg— Sao Paulo— Vienna— Zurich19

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