TRELLEBORG ENGINEERED PRODUCTS

Acoustic VibrationIsolation Bearings

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TRELLEBORG ENGINEERED PRODUCTS

Urban land availability for building new structures is becoming more restrictive.

There appears to be an increasing trend to construct new performance spaces such as Cultural Centres above, or in close proximity to, existing railway lines, underground systems, major roads and other “noisy” infrastructure.

Performance halls located on vibration contaminated land need to be stringently designed to minimise the potential for any sound transmission through the foundations.

Trelleborg is a global supplier of acoustic bearings for building isolation.Concert halls, lyric theatres, movie production studios and other noise and vibration-sensitive buildings often require isolation from the surrounding structure.

Acoustic bearings are a reliable and durable solution for supporting loads, accommodating movements and attenuating the effects of noise and vibration transmitted into the structure.

Recent ProjectsSingapore Theatres on the Bay, Concert Hall

and Lyric Theatre

Hong Kong Hong Kong Movie City

Budapest National Philharmonic Hall, Cultural Complex

Adelaide Adelaide Convention Centre

Brunei Sultan of Brunei’s Palace, Helicopter Pad

Sydney Angel Place

Brisbane Queensland Conservatorium of Music

Perth Lakeside Joondalup Theatres

Brisbane Queensland Performing Arts Complex

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TRELLEBORG ENGINEERED PRODUCTS

Bearing Design

Acoustic isolation involves supporting the structure on a comprehensive system of bearings, specially designed to perform under the specified operating criteria. Selecting the appropriate bearing design is dependent on a large number of variables including:

• Characteristics of the disturbance frequencies

• Degree of vibration attenuation required of the bearings (ie. required natural frequency of the bearing pads)

• Vertical and lateral loads

• Wind and earthquake loads

Trelleborg custom design all bearings to meet the specified static deflection and natural frequency requirements. Bearings are generally designed as a composite of rubber and steel.

The quantity and geometry of the steel plates principally determine the load bearing and stiffness characteristics.

Bearings are designed with sufficient thickness to ensure they are not overstressed when operating over the full load range.

Under dynamic load conditions the effectiveness of the bearings is dependent on their dynamic-to-static stiffness ratio.

In general, we manufacture most of our bearings using natural rubber to maintain low dynamic-to-static stiffness ratios (eg. 1.2 - 1.3).

Bearings can be supplied pre-compressed to assist with construction.

This avoids problems associated with the bearings gradually deflecting as additional structure increases the support weight. Bearings can also be designed as continuous strips to support walls.

We use tried and proven modelling procedures such as mathematical modelling and Finite Element Analysis (FEA) to predict the load and deflection characteristics.

All designs are verified by testing prototype bearings prior to commencing production. Full destruction tests can be completed on prototype bearings if required.

Trelleborg has an experienced engineering team available to discuss your project in the design phase, to enable accurate sizing of columns and provide options for reducing construction costs.

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TRELLEBORG ENGINEERED PRODUCTS

Uplift Loads

Trelleborg Laminated rubber bearings are suitable for carrying load by compression and under no circumstances should they be subjected to tension.

If tensile forces could arise due to uplift in the bearing (eg. seismic or wind loads), we can design a multi-bearing arrangement to restrain the bearing under uplift loads.

Fire Protection

We can design bearings with an inherent system of fire protection (eg. 2 hour fire rating).

Alternatively we can design and supply a fire protection system to be installed around the column or structure supporting the bearing.

All fire protection systems for acoustic isolation bearings should be designed so the potential for bridging between the substructure and superstructure is minimised.

SUPPORT COLUMN

TOP BEAM

Bearing assembly designed to withstand uplift loads

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TRELLEBORG ENGINEERED PRODUCTS

Failsafe Design

If required, we can design bearings with either an internal or external failsafe system.

Failsafe devices are provided to support the structure in the highly unlikely event of catastrophic failure (eg. fire).

Failsafe devices typically consist of cylindrical steel components designed to support the column load.

In acoustic isolation applications, the clearance between the failsafe device and upper beam under full load is critical.

This gap must not be bridged under normal

operation however must also minimise the potential movement in the structure if any bearings fail.

Our focus is to supply high quality products that provide superior acoustic performance. In general, all bearings are fully tested and verified using our extensive in-house testing facilities.

Our manufacturing site in Brisbane, Australia is certified to the Quality Standard ISO 9001.

We are focussed on working closely with our clients to develop innovative designs, cost-effective solutions and ensure on-time deliveries.

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TRELLEBORG ENGINEERED PRODUCTS

Trelleborg Hi-Shear Bearings

Trelleborg has developed an innovative elastomeric bearing for acoustic isolation of low frequency vibrations (eg. < 8 Hz). The conventional method often used to isolate low frequency vibrations is to install an arrangement of steel springs.

Elastomeric bearings provide superior acoustic isolation over the long term compared with other alternatives such as steel springs.

• Elastomeric bearings contain inherent material damping that limits vibration amplification at the system’s natural frequency. Steel springs inherently lose vibration isolation at their internal resonance and often require supplementary damping systems.

• More corrosion resistant compared with steel springs

• Less mechanical complexity compared with steel springs

• History of good long-term durability indicates an effective life in excess of 50 years. Resistance to degradation is superior to steel and concrete.

Lo-frequency bearings can be supplied either compressed or uncompressed. They are specially designed with increased stability and increased lateral restraint.

Lo-Frequency Bearings

Trelleborg has developed innovative manufacturing techniques to significantly increase the shear stiffness of bearings supporting vertical loads.

Laminated bearings typically have very low ratios of shear stiffness to vertical stiffness (ie. < 1%).

Our Hi-Shear Bearings provide shear stiffnesses, in all lateral directions, in excess of 4% of the vertical stiffness.

To provide lateral restraint against wind and earthquake loads, acoustic isolation systems conventionally employ a large number of lateral bearing assemblies that are often supplied pre-compressed.

Our bearings with the integrated design of high vertical and shear stiffness significantly reduce or eliminate the requirement for supply and installation of pre-compressed lateral bearing assemblies and the additional structure required to support these lateral bearings.

Our integrated bearings provide a simple, cost effective, more reliable and acoustically superior system of isolation.

Recent projects include the Theatres on the Bay in Singapore, Hong Kong Movie City and the Adelaide Convention Centre in Australia.

1000kN

50kN

SUPPORT COLUMN

BEAM

5mm

railway vibrations

Typical Hi-shear laminated bearing

PRECOMPRESSION BOLT(release after installation)

BEAM

SUPPORT COLUMN

railway vibrations

Compressed low frequency acoustic vibration isolation bearing

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TRELLEBORG ENGINEERED PRODUCTS

The majority of the building isolation projects we have been involved with are the result of noise and vibration from rail systems.

We also have expertise in preventing or alleviating the effects of sound transmission from the source.

Trelleborg is a leading supplier of rail track isolation systems including floating slab track bearings.

If a high degree of vibration attenuation is required to acoustically isolate a performance space then our recommendation is a combined system of acoustic bearings to isolate vibrations into the building structure and floating slab track bearings to isolate noise and vibration out of the rail structure.

This “double isolation” system has been specified on a number of our projects.

Trelleborg Floating Slab Track Bearings

WWW.TRELLEBORG.COM/ENGINEEREDPRODUCTS

Trelleborg Engineered Products Australia Pty Ltd, Brisbane Head Office, 515 Zillmere Rd, Zillmere, Queensland, Australia 4034

Tel: +61 7 3866 7444 Fax: +61 7 3263 4912

Trelleborg Engineered Products is part of the Trelleborg Offshore

& Construction business area of the Trelleborg Group. Trelleborg

Engineered Products is a leading global developer, manufacturer and

provider of engineered polymer solutions to the energy, infrastructure

and mining industries. Performing in some of the harshest

environments on earth, its principal products are sealing systems

for tunnels, a wide range of bearings, polymer solutions for floatover

technology and wear resistant products for the mining industry.

With local support, a track record of over 100 years and its everday

ingenuity, customers can rely on Trelleborg Engineered Products to

deliver innovative polymer solutions that significantly improve the

quality, safety and efficiency of its customers’ operations worldwide.

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Perth Office, 25 Glassford Rd, Kewdale, Western Australia, Australia 6105

Tel: +61 8 9256 6000 Fax: +61 8 9353 5990

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