Acoustic Vibration Isolation Bearings - Trelleborg.com.au

Acoustic Vibration
Isolation Bearings

Trelleborg Acoustic Vibration
Isolation Bearings
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
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 vibrationcontaminated
land need to be
stringently designed to minimise the
potential for any sound transmission
through the foundations.
Recent Projects
Singapore 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

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 precompressed
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.

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 multibearing
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.
TOP BEAM
SUPPORT COLUMN
Bearing assembly designed to withstand
uplift loads

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 inhouse
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.

Trelleborg Hi-Shear Bearings
Trelleborg has developed innovative
manufacturing techniques to
significantly increase the shear stiffness
of bearings supporting vertical loads.
50kN
1000kN
SUPPORT COLUMN
railway vibrations
5
mm
BEAM
Typical Hi-shear laminated bearing
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 precompressed.
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.
Lo-Frequency 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.
PRECOMPRESSION BOLT
(release after installation)
BEAM
SUPPORT COLUMN
railway vibrations
Compressed low frequency acoustic
vibration isolation bearing
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.

Trelleborg Floating Slab Track Bearings
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.

Other Trelleborg Products
Elastomeric Bearing
Pads & Strips
Elastomeric Bridge Bearings
Pot Bearings
Fixed (TF), Guided (TGe), Free (TGa)
Rail Track Isolation Systems
Structural Sliding
and Fixed Bearings
Impact Products
Fenders, Bumpers, Guards and Stoppers
Brisbane
Phone +61 (7) 3866 7444
Facsimile + 61 (7) 3263 4912
Email: tqr.info@trelleborg.com
www.trelleborg.com.au
Perth
Phone +61 (8) 9256 6000
Facsimile + 61 (8) 9353 5990
Email: admin.perth@trelleborg.com.au
www.trelleborg.com.au
CREATIVE 9089 7/08