High Damping Natural Rubber Seismic Isolators - SILER

www.tarrc.co.uk

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

[email protected]

SILER International Workshop 2013 Rome (Italy), June 18th - 19th 2013

mailto:[email protected]

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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SILER International Workshop 2013 Rome (Italy), June 18th - 19th 2013

www.tarrc.co.uk

SILER International Workshop - Rome (Italy), June 18th - 19th 2013

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

http://en.wikipedia.org/wiki/File:Conwy_Castle_and_Railway_Bridge.jpg

http://en.wikipedia.org/wiki/File:Britannia_Bridge_-_circa_1852.jpg

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Melbourne Viaduct, 1889

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)

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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SILER International Workshop - Rome (Italy), June 18th - 19th 2013 10

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

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)

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?

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

• 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

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

A retrofit Base-isolation project in Armenia

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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0

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

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

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

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

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Documents

High Damping Natural Rubber Seismic Isolators - SILER