High Damping Natural Rubber Seismic Isolators - SILER
Transcript of High Damping Natural Rubber Seismic Isolators - SILER
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Tun Abdul Razak Research Centre (TARRC)
A RESEARCH & PROMOTION CENTRE OF THE MALAYSIAN RUBBER BOARD
Brickendon lane, Hertford, SG13 8NL -UK
High Damping Natural Rubber Seismic Isolators Historical Development and Performance
Hamid AHMADI Head: Industrial Support and Engineering Design Division
SILER International Workshop 2013 Rome (Italy), June 18th - 19th 2013
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OUTLINE
•Natural Rubber-Steel Laminated bearings- History of its development and its use by the Structural Engineering community • Load – Deformation behaviour of High Damping Natural Rubber (HDNR) isolators Features of response of HDNR – Models available •Ageing and longevity of HDNR isolators
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Use of rubber was limited to
• erasers
• waterproofing
• elastic strips for underwear
until Hancock patented vulcanization in 1844….
• subsequent applications developed rapidly.
Railway buffer manufactured at Bradford-on-Avon
by George Spencer & Co.
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Use of Natural Rubber as “Bridge Bearings” • Britannia Bridge (1846) crosses Menai Strait -Anglesey, North Wales Tubular bridge of Wrought Iron rectangular box section on stone – longest span 140 m, designed and built by Robert Stephenson- Fire damage and rebuilt in 1970 in steel and concrete Conway Bridge (opened 1948) designed and built by Robert Stephenson still remaining. Used 50mm thick pad of rubber to reduce shock transmitted to the stone piers • Bridge across Saale River near Grizehna (1853). Main girder rest on cast iron base plate supported by Ashlars of sandstone piers1/2 inch pad of rubber used to accommodate expansion of the girders reduce Transmission of vibration
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Melbourne Viaduct, 1889
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Eugene Freyssinet (Patent 1956) Buckling of block of rubber ? “Vertical stiffness inversely proportional
to thickness unlike the horizontal stiffness”
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Similarly
Evan Melfyn Lewis From Walton-on-Thames Surrey (1956)
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load
deflection
3-layer (compression) 1-layer
(compression)
Both units (shear)
Bulk Modulus ~ 2000 MPa
Shear Modulus ~ 0.5 MPa
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Sikorsky H-60 (Blackhawk) has elastomeric blade retention
bearings.
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Bonding rubber to metal
• Ebonite (1869)
• Brass plating (70/30 Copper/Zinc): British patent by Charles Sanderson 1862; commercial process in USA in the 1920s
• Bonding cements solution of a polymer with higher Tg than ebonite, mixed with reactants
for crosslinking it to the rubber if incompatible, and corrosion inhibiting agents. Proprietary ones from the 1930s (Typly)
Buchan 1959
• LORD began developing better bonding agents for rubber in 1943 and launched ChemlokR
adhesives in 1957
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Pelham Bridge, Lincoln built 1956 W.S. Atkins, BRPRA (now TARRC) , Andre Rubber company
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Pelham bridge In the late 1950’s a British committee was set up by the UK Ministry of Transport produced a Standard for rubber-steel laminated bearings
•A success: no failures
•Several ideas adopted internationally (e.g. CEN1337 part3 (2005), AASHTO method B
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•emphasis on caution
• modest load and shear strain limits
• high standards required for material properties (eg tensile strength, elongation at break, ozone resistance, compression set)
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The world’s first building mounted on bonded rubber-steel laminated bearings to prevent transmission of vibrations caused by moving trains Block of apartments located above the St. James Park underground station-London
Albany Court built in 1966 W.S. Atkins, TARRC , Andre Rubber company
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Can we achieve a low enough vertical
stiffness to isolate buildings above
underground trains from vibration?
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MARRIOTT HOTEL
ALEXANDRA RD
105-109 PARK ROAD
WELLINGTON HOSPITAL
ALBANY COURT APARTMENTS (1966)
HILTON METROPOLE
PARK HOUSE
ST PANCRAS CHAMBERS
BARBICAN ARTS CENTRE
PROCESSION HOUSE
BLACKFRIARS STATION
ROYAL FESTIVAL HALL
1 POULTRY LANE
LION PLAZA
BROADGATE TOWER
IDEA STORE, EC1
LLOYDS AVENUE DEVELOPMENT
1 AMERICA SQUARE
DOCKLANDS LIGHT RAILWAY
THAMES BARRIER
HIGHBURY COAL YARD, LIVERPOOL ROAD, N7
11-13 HOLBORN VIADUCT
30 QUEEN STREET
101 QUEEN VICTORIA ST
CARR STREET, EC14
17-21 NORTHWOLD ROAD, N16
PLAZA
ESSO GLEN, VICTORIA
ROYAL OPERA HOUSE
LANGHAM HOTEL
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1972 Rubber Developments 25, 48
New 36-floor law courts, Sydney, Australia was mounted on NR isolators.
Speculated that rubber springs might also be used as anti-seismic mounts
Siegenthaler (1972) wrote to TARRC “we have already done it”
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Elementary school "Pestalozzi"
Skopje, 1966
Vertical ~ 2Hz
Horizontal ~ 0.64Hz
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• Skopje- Macedonia- Pestalozzi elementary school , opened 1969- Mounted
on blocks of Low damping NR bearings
• Lambesc, France - 600 pupil school on 152 laminated bearings, 40 IRHD NR, low damping- 1979.
Rubber springs to protect buildings from earthquake
• Research on isolation at DSIR, NZ, 1974 – 1983
1976 Patent on Lead-plug rubber bearings (Robinson)
1977 Close working relationship with Ministry of Works - approval for projects
1983 William Clayton building
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• Research at TARRC commissioned from W S Atkins:
“Preliminary report on the use of rubber springs to protect building in earthquake zones” May 1973
• “Building on springs: Time history analysis” - Shaking table tests carried out at UC Berkeley with Prof Jim Kelly
Collaboration with EERC at UC Berkley led to the development of High Damping Natural Rubber
Rubber springs to protect buildings from earthquake
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Foothill Communities Law and Justice Center San Bernardino County, California, USA
First building in the world to use High Damping Natural Rubber bearings
Completed in 1985 at a cost of $38US million, mounted on 98 bearings
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A United Nation Industrial Development Organisation
(UNIDO) funded project on:
“Use of Natural Rubber-based Bearings for Earthquake
Protection of Small Buildings” Duration: 1991- 1994
Carry out research on the rubber formulations and design
of bearings suitable for use in developing countries (
relatively light weight low cost housings)
Demonstrating the use of NR based isolation in a small
purpose built building typical of many developing
countries (3-4 storey apartment block)
Widespread publicity to the results of the project
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8-story multi-family housing block in Shantou City 1994
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A retrofit Base-isolation project in Armenia
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Base-isolation of a demonstration building in Ain Defla- Algeria, opened 2007.
The building is three-storey above ground and one below ground with
reinforced concrete frame structure, irregular plan and elevation.
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Shear stress-strain loops for a NR compound
Upper set: Virgin sample tested at successively larger strains (Mullins effect)
Lower set: The same sample tested at successively larger strains with a 250%
scrag interposed between each test (Fletcher-Gent effect).
“Fletcher-Gent”
or “Payne” effect
[Amplitude
dependant cyclic
response]
“Mullins “effect
Strain history
effect
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-1.6
-1.2
-0.8
-0.4
0.0
0.4
0.8
1.2
1.6
-150 -100 -50 0 50 100 150
Stre
ss (M
Pa)
Strain (%)
Hysteresis loops for a HDNR compound at 0.5 Hz Blue loops - First cycle (“Virgin”) Red loops – Tenth Cycles
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0.0
0.1
0.1
0.2
0.2
0.3
0.3
0.4
0.4
0
1
2
3
4
5
6
1 10 100
tan d
Mo
du
lus
(MP
a)
Strain (%)
1st sequence 1st cycle
1st sequence 10th cycle
Dynamic properties for a HDNR compound at 0.5 Hz Blue curves - First cycle (“Virgin”) Red curves - Tenth cycle
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0.0
0.1
0.1
0.2
0.2
0.3
0.3
0.4
0.4
0.5
0
1
2
3
4
5
6
1 10 100
tan d
Mo
du
lus
(MP
a)
Strain (%)
1st sequence 1st cycle
2nd sequence 1st cycle
1st sequence 10th cycle
2nd sequence 10th cycle
Dynamic properties for a HDNR compound at 0.5 Hz Blue curves - First cycle (“Virgin”) Red curves - Tenth cycle 2nd sequence – After 10 cycles at 250% strain
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-6
-4
-2
0
2
4
6
8
-300 -200 -100 0 100 200 300
Axis Title
Hysteresis loops for a HDNR compound at 0.5 Hz Blue loops – 1st to 10th cycles (“Virgin”) Red loops – 1st to 10th cycles, 2nd sequence
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1
2
3
4
5
6
7
8
9
10
0% 100% 200% 300% 400% 500% 600%
Stre
ss (n
om
inal
) MP
a
Strain (nominal)
10 mm/min loading rate
Stress-Strain curve in shear for Natural Rubber
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Ahmadi et al. 1994, Ahmadi & Muhr 1997
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MOTIVATION Need for a model that predicts the stress-strain behaviour of
filled rubber when subjected to time varying inputs-
quasi-static, cyclic, creep suitable for engineering applications
The model should be:
Simple to implement in commercial FEA codes
As few parameters as possible
Related to physical processes
-used outside characterisation test
regime
-helps to achieve small number of
parameters
Simple characterisation tests
Parameters ideally related to the compound formulation
Predict the effect of temperature
Predict response to strain history (Mullins effect)
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‘Viscoplastic’ Model (One Dimensional)
• Hyperelastic – underlying
behaviour. This is similar to
that described earlier –
except removing the ‘Davis’
term used to model fillers.
• Viscoelastic – rate effects.
• Elastoplastic – rate
independent hysteresis.
VE HE EP
elastoplactic part veephe
hyperelastic part
viscous part
[Ahmadi et. al.
2003, 2005
& 2008]
[Ahmadi & Muhr
2009]
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0
0.5
1
1.5
2
2.5
3
3.5
0 0.2 0.4 0.6 0.8 1 1.2
G'/M
Pa
shear amplitude
c) G', T = 296K EDS19
EDS14
EDS15
EDS16
EDS19 model
EDS14 model
EDS15 model
EDS16 model
[Muhr 2009]
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0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
230 250 270 290 310 330 350 370 390 410 430
G'/M
Pa
T/K
EDS19
EDS14
EDS15
EDS16
EDS19(296)*T/296
EDS14 model
EDS15 model
EDS16 model
EDS19 model
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1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
230 250 270 290 310 330 350 370 390 410 430
G''/
MP
a
T/K
EDS19
EDS14
EDS15
EDS16
EDS19 VE model
EDS14 model
EDS15 model
EDS16 model
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Material parameters in the form of:
Hyperelastic contribution:
Elastoplastic contribution:
g
s1
epl epl1
s
Simple shear data
Uniaxial tension data
Perfect plastic material model
Kinematic hardening rule
Abaqus syntax (i.e.):
*ELASTIC
E, u
*PLASTIC, HARDENING=KINEMATIC
s1, epl1
s1, epl2
Abaqus syntax (i.e.):
*HYPERELASTIC, YEOH
C1, C2, C3
Mesh Overlay Method
[Ahmadi et. al. 2005]
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Uniaxial and Bi-directional models for isolators
including Mullins effect
European Conference on Constitutive Models for Rubber (ECCMR)
24-28 June 2013 San Sebastian-Spain
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From hub, solid tyre is about 80 years old
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90 – 95 Shore A
60 – 65 Shore A
in the absence of antioxidant , oxidation is so rapid
(autocatalytic) that all oxygen is consumed close to the
surface and the bulk of the rubber is unaffected
80 year old solid tyre: hard layer (~0.5mm thick) and cracks into the transition
layer (~4mm deep)
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1 division is 1mm
A section of the 100-year old rubber from Melbourne Australia – still in good condition
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Pelham bridge
8 bearings removed for longevity analysis funded by Japan Atomic Power Company 38 years later K N G Fuller & A D Roberts
Int. Rubber Conf., KL, 1997
at ambient temperature, with an ample reservoir of antioxidant, oxidation proceeds slowly along with anaerobic chemical changes – physical properties not much affected
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Shear stiffness 7% greater than original prototype
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• Yama-age Bridge Japan (Bridgestone HDR)
Test property
At construction 1992
2002
Change %
Shear stiffness kN/mm
7.6 7.9
4
7.5 7.7 3
Damping %
18.5 18 -2
17.5 18 4
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OUTLINE OF RESEARCH OUTPUT •Modelling the force-deformation behaviour of the isolators
Design equations ( shear stiffness, compressive stiffness, instability)
uniaxial non-linear hysteretic models for earthquake engineering analysis
linearisation versus nonlinear analysis
mechanics of the bearing- shear capacity, tensile conditions, end condition
•Development of a range of High Damping NR compounds meeting the
national and international standards
•Role of damping in the isolators on the response of the structure
•Manufacture of bearings (Applied physics, quality control)
• FE Simulation of:
Force deformation behaviour (Generalised model for the rubber, role of
flexibility and plasticity of the steel plates on shear stiffness and damping)
Predicting fatigue life
Predicting the state of the cure and optimisation of cure process
Thank you for your attention
www.tarrc.co.uk
SILER International Workshop - Rome (Italy), June 18th - 19th 2013