TESTING OF SEISMIC PROTECTION DEVICES

Agostino Marioni1ST EFAST Workshop – Ispra, 2-3 March 2009

The most common Standards for Antiseismic Devices

In Italy:• Norme Tecniche per le Costruzioni, 14/01/08 (will be

superseded, as far as concerns antiseismic devices, by EN 15129)

In Europe:• prEN 15129 European Standard for Antiseismic Devices

(formal vote in progress, should become EN shortly)In USA:• AASHTO Guide Specification for Seismic Isolation

DesignWorldwide• ISO 22762 (only HDRB and LRB)

Performance oriented classification of antiseismic devices (according to prEN15129)• Rigid connection devices

– Restraints (Dowels and Guides)– Hydraulic connecting devices

• Displacement Dependent Devices– Linear Devices– Non Linear Devices

• Velocity Dependent Devices• Isolators

– Sliders– Rubber Bearings (High, Low Damping or

LRB)– Sliding Pendulum

Type oriented classification of anti-seismic devices

• HDRB (High Damping RubberBearings)

• LRB (Lead Rubber Bearings)• Hysteretic Dampers• Sliding Pendulum Isolators• Hydraulic Devices

– Viscous Dampers– Dynamic connection devices or Shock

Transmission Units - STU

Functions of a base isolation system

• Support the vertical load• Provide lateral flexibility• Provide a restoring force• Damp the energy

Isolators are devices providing the four functions

TEST REQUIREMENTS ACCORDING TO prEN 15129

General rule:There are two kinds of tests:1. Type testing to be performed on each

type of device and to be repeated if the design load and displacement deviate more than 20% from the prototype

2. Factory Production Contol to beperformed on the current production withthe specified frequency

TEST REQUIREMENTS ON FUSE RESTRAINTS

1. Type testing– Service load test– Fatigue test– Brake away test

2. Factory Production Control– Only material testing

TEST REQUIREMENTS ON DYNAMIC CONNECTION DEVICES (STU)

XCyclic load test

XOver load test

5%XImpulsive load test

XSeal wear test

5%XLow velocity test

100%XPressure test

FPCType testTest

TYPICAL FEATURE OF A STU

Shock Transmission Units (STU)

dynamic testing

Shock Transmission Units (STU)

Typical output of an impulsive load test

Shock Transmission Units (STU)

Typical output of a cyclic load test

Typical output of a low velocity test

Shock Transmission Units (STU)

TEST REQUIREMENTS ON DISPLACEMENT DEPENDANT DEVICES

1. Type testa) 5 force – displacement cycles at 25%, and

50% Dd + 10 cycles at 100% Ddb) Ramp test up to Dd x γb x γx or Vd x γb x γx

with γb = 1,15 and γx = 1,2 or 1,52. Factory Production Control

– Test a) on 2% of the devices

DYNAMYC TESTS ARE NOT REQUIRED

DISPLACEMENT DEPENDENT DEVICES(HYSTERETIC DAMPERS)

Typical force – displacement test

MULTIDIRECTIONAL HYSTERETIC DAMPER

Force – displacement test

MULTIDIRECTIONAL HYSTERETIC DAMPER

Typical output of a force – displacement test

TEST REQUIREMENTS ON VELOCITY DEPENDENT DEVICES (VISCOUS DAMPERS)

XWind load cycle testXStroke verification

5%XDamping efficiency5%XConstitutive law test

XSeal wear test5%XLow velocity test

100%XPressure testFPCType testTest

Test verification of the constitutive law of a viscous damper with exponent α = 0,15

RITEGNO SISMICO FLUIDODINAMICO TIPO FD 750/100VERIFICA SPERIMENTALE DELLA CURVA TEORICA

0

100

200

300

400

500

600

700

800

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1000

0 20 40 60 80 100 120 140 160

velocità (mm/s))

forz

a (k

N)

Curva teorica Valori sperimentali della forza di reazione

Test verificationof the energy

dissipation of a viscous damper with exponent α= 0,15 subject to

10 sinusoidalcycles of 50 mm

displacement

100 110 120 130 140 150spostamento (mm)

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MTS856, forma d'onda sinusoidaleDIAGRAMMA FORZA-SPOSTAMENTOFrequenza = 1 Hz

TEST REQUIREMENTS ON ELASTOMERIC ISOLATORS (HDRB&LRB)

XCompression at zero displ.FPCType testTest

20%XCompression stiffness20%XK and ξ under cyclic deformation

XVariation of K and ξ with agingXCreep under vertical load

XLateral capacity with V min and maxXVariation of K and ξ with cyclingXVariation of K and ξ with temperatureXVariation of K and ξ with frequency

20%XK under ramp loading

High Damping Rubber Bearing HDRB

Lead Rubber Bearing (LRB)

Horizontal load – deflection plot of an HDRB

BI-AXIAL TEST ON A HDRB UTILIZING A SLIDING SURFACE

BI-AXIAL TEST ON A PAIR OF HDRB

TEST REQUIREMENTS ON CURVED SURFACE SLIDERS

(SLIDING PENDULUM ISOLATORS)

5%XCompression at zero displacementFPCType testTest

XAging test5%XSliding isolation tests

XStatic coefficient of friction5%XFriction in service conditions

ALGAPEND Sliding Pendulum with one spherical sliding surface

ALGAPEND Sliding Pendulum with twospherical sliding surfaces

ALGAPEND Sliding Pendulum with twoperpendicular cylindrical sliding surfaces

TEST OF AN ALGAPEND ISOLATOR AT THE EUCENTRE LABORATORY

TEST OF AN ALGAPEND ISOLATOR AT THE EUCENTRE LABORATORY

DYNAMIC TEST OF AN ALGAPEND ISOLATOR AT THE EUCENTRE LABORATORY - TYPICAL OUTPUT

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Disp (mm)

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TEST REQUIREMENTS ON COMBINATION OF DEVICES

1. Type test on a complete device2. Factory production control on the

individual components according to the relevant parts of prEN15129 or EN1337

Typical example of a combination of devices (hysteretic slider):

pot bearing according to EN 1337-3 (blue) combined with hysteretic dampers (green) and shock transmission units (gray)

BI-AXIAL TEST OF A HYSTERETIC SLIDER

TEST REQUIREMENTS FOR HDRB AND LRB FROM ISO 22762

TEST REQUIREMENTS ACCORDING TO AASHTO GUIDE SPECIFICATIONS

• Prototypes tests: 2 prototypes. Scaledisolators only if approved by the Engineerand no equipment available. Load cyclesup to 1,25 design displacement.

• Routine tests on 100% of the devices

SUMMARY OF THE REQUIREMENTS OF THE TESTING EQUIPMENTS

Requirements for testing of ShockTransmission Units• Uniaxial dynamic equipment with:

– Force up to 20 MN (Carquinez Bridge = 1,6 MN)

– Stroke ~100 mm– Velocity ~ 100 mm/s– Theoretical power requirement: 2 MW

Requirements for testing of VelocityDependent Devices (Viscous Dampers)

• Uniaxial dynamic equipment with:– Force up 5 MN (Rion Antirion Bridge = 3

MN)– Stroke ~2000 mm– Velocity ~ 500 mm/s, however sometimes

are required velocities up to 2200 mm/s tosimulate near fault effects

– Theoretical power requirement: 2,5 to 11 MW

Requirements for testing of RubberIsolators (HDRB & LRB)The most common Isolators may have 1200 mmDiameter and would require:• Vertical load (2xdesign load) 35 MN• Horizontal load (at tanγ=2,5 and G=1,4) 4 MNSome manufacturers can produce isolators up to1750 mm diameter and in this case therequirements would be:• Vertical load 75 MN• Horizontal load 8,5 MN

Requirements for testing of RubberIsolators (HDRB & LRB)• Bi-axial dynamic equipment with:

– Vertical force up to 50 MN (however 75 MN couldalso be required for 1750 mm dia.)

– Vertical stroke ~50 mm– Horizontal force up to 5 MN (or 10 MN for 1750 mm

diameter)– Horizontal stroke ±600 mm for most cases but

±1200 mm could be required for near fault effects– Frequency up to 0,5 Hz and velocity up to 2200

mm/s when near fault effects shall be simulated

Requirements for testing of Sliding PendulumIsolators• Bi-axial dynamic equipment with:

– Vertical force up to 50 MN (however 100 MN couldalso be required in some cases)

– Vertical stroke ~200 mm– Horizontal force up to 5 MN (10 MN could be

required in some cases)– Horizontal stroke ±600 mm for most cases but

±1200 mm could be required for near fault effects– Frequency up to 0,5 Hz and velocity up to 2200

mm/s when near fault effects shall be simulated

CONCLUSIONS• The demand of tests on antiseismic devices will

tend to increase with entering in force of the European Standard EN 15129 and the increaseof the number of structures incorporating suchdevices

• Near fault effects require exeptionalperformances of the testing equipments

• New testing facilities should include device-oriented equipments and consider the aboverequirements

THANKS FOR YOUR ATTENTION !a.marioni@alga.it