Characterization of the performance and - Prota … · Characterization of the performance and ......

PROTA

Characterization of the performance and

durability of full scale seismic isolation and

energy dissipation devices

Gianmario Benzoni University of California San Diego

Caltrans Seismic Response Modification Device Test Facility SRMD

PROTA


DIFFICULTIES FOR TECHNOLOGY

IMPLEMENTATION:

Acceptance criteria based on experimental validation

often not correctly designed

“Traditions” in design and construction

Design approach too conservative (codes)

Economical decision usually based on the initial cost of

construction

PROTA


UTAH STATE CAPITOL

PROTA


SAN FRANCISCO CITY HALL, CALIFORNIA

PROTA


Strategic Facilities:

911 EMERGENCY COMMUNICATION CENTER –S.F, CALIFORNIA

PROTA


CALTRANS TRAFFIC CENTER –SAN DIEGO, CALIFORNIA

Number & Type of Isolators:

40 HDR

PROTA


Mills-Peninsula Medical Center

Burlingame, Ca

42000 m2 area

2 miles from San Andreas fault PROTA


176

Triple-Pendulum

(E.P.S.)

PROTA


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* Represents 19% of the total bridge population of 25,000. Status 1-11-00

California Department of Transportation

(Caltrans) Seismic Bridge Safety Program Program N. of Bridges

identified forretrofit

Cost($ ML)

Completiondate

Phase IRestrainers

1261 54 Aug. 89

Phase IISingle column bents

1039 850 Mar 00

Phase IIIMulti column bents

1155 1350 Aug. 05

Phase IVToll bridges

7 2619 Aug. 05

Phase VLocal agencies

1200 1200 Aug. 05

Total 4662*

6073

PROTA

• CALTRANS Toll Bridge Seismic Retrofit Program – Benicia - Martinez Bridge *

– Carquinez Bridge

– Richmond - San Rafael Bridge

– San Francisco - Oakland Bay Bridge *

– San Mateo - Hayward Bridge

– Vincent - Thomas Bridge

– San Diego - Coronado Bridge

– Antioch Bridge

– Dumbarton Bridge

• Need of full scale tests

• Range of force, displacement, velocity

PROTA

Caltrans SRMD Lab

At UCSD

PROTA


Vertical Longitudinal Transverse

Force 53,400 kN (12,000 kips)

8,900 kN (2,000 kips)

4,450 kN (1,000 kips)

Displacement 0.127 m (5 in.)

1.22 m (48 in.)

0.61 m (24 in.)

Velocity 254 mm/s (10 in./s)

1778 mm/s (70 in./sec)

762 mm/s (30 in./sec)

Clearance Up to 1.52 m (5 ft)

~ 4 m (13 ft)

Relative rotation

5 2 2

SRMD technical specifications

PROTA


PROTA



Benicia-Martinez Bridge Friction Pendulum devices PROTA


Lessons from Laboratory Tests

PERFORMANCE OF

ISOLATORS/DAMPERS TESTING PROTOCOL

MACROSCOPIC EVIDENCE OF CRITICAL DESIGN AND FABRICATION

CONCEPTS

UNEXPECTED PERFORMANCE

LACK OF RATIONAL TESTING PROTOCOLS AND ACCEPTANCE

CRITERIA

LACK OF RELIABILITY OF NUMERICAL MODELS PROTA


MACROSCOPIC EVIDENCE OF CRITICAL

DESIGN AND FABRICATION CONCEPTS

PROTA


TESTING PROTOCOLS AND ACCEPTANCE CRITERIA

Attempt to combine in one test multiple performance

characteristics verifications

Acceptance criteria established on designer “wish list”

that do not account for variability of the specific device

response (stick-slip, thermal effects etc.)

Prototype testing protocols “project specific”

Mono-directional vs multi-directional type of motion

Complete absence of requirements about durability of devices

Incomplete requirements about shape of excitation, time

between tests (temperature), sensors type and location

PROTA


DESIGNER MANUFACTURER

MOST CRITICAL TREND:

CODE

Specific knowledge still limited for designers

The designer considers himself a NON-EXPERT

Device manufacturer

PROTA

Caltrans Seismic Response Modification Device Test Facility

SRMD

PROTOTYPE TESTS (2 PER TYPE)

PROOF TESTS (Production acceptance)

TEST R&D

Design

parameters

Device

limits

The designer needs to be FULLY involved in the

qualification process of the device

and be informed on the long term performance of products PROTA

Caltrans Seismic Response Modification Device Test Facility

SRMD

LEAD RUBBER BEARING @ 450% PROTA


Estrapolation of the experimental performance of devices

to other similar devices but with different dimensions and

capacity

“The father of friction research, Leonardo da Vinci,

was probably the first who consciously investigated

pairs of material. From that time, the unfortunate

misunderstanding about a friction ‘coefficient’ as a material

property has grown, and it is still deeply rooted in the mind

of engineers,….[However] the friction coefficient is just a

convenience, describing a friction system and not a material

property” G.Salomon, 1964

PROTA

EFFECT OF VERTICAL LOAD VARIATION

EFFECT OF VELOCITY (STRAIN RATE)

EFFECT OF TEMPERATURE

ELASTOMERIC

BEARINGS

FRICTION-BASED

ISOLATORS


EFFECT OF MULTI_DIRECTIONAL INPUT

PROTA

Peak Shear Forces

2000 2500 3000 3500 4000 4500 5000 5500 6000

Vertical load (kN)

500

1000

1500

Fo

rce (

kN

)

1st cycle

2nd cycle

3rd cycle

Max 4-5%

LEAD-RUBBER BEARINGS:


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Peak Shear Forces

0 200 400 600 800 1000

-1500

-1000

-500

0

500

1000

1500

Fo

rce (

kN

)

1st cycle

2nd cycle

3rd cycle

negative force

0 200 400 600 800 1000 1200 1400

1st cycle

2nd cycle

3rd cycle

negative force

0 200 400 600 800 1000 1200 1400

Peak velocity (mm/s)

1st cycle

2nd cycle

3rd cycle

negative force

V=2224 KN (2.7 MPa) V=4004 KN (4.9 MPa) V=5783 KN (7.1 MPa)

Max 70.6% Max 73.8% Max 64.5%

45% 45% 45%

30% 30% 30% PROTA


Yield Shear Force

2000 2500 3000 3500 4000 4500 5000 5500 6000

Vertical load (kN)

200

300

400

500

600

700

800

900

Yie

ld s

he

ar

forc

e Q

d (

kN

)

1st cycle

2nd cycle

3rd cycle

Max 7.6%

PROTA


0 200 400 600 800 1000

100

200

300

400

500

600

700

800

900

1000

Yie

ld S

hea

r F

orc

e Q

d (

kN

)

0 200 400 600 800 1000 1200

100

200

300

400

500

600

700

800

900

1000

1st cycle

2nd cycle

3rd cycle

0 200 400 600 800 1000 1200

100

200

300

400

500

600

700

800

900

1000

Yield Shear Force

V=2224 kN (2.7 MPa)

V=4004 kN (4.9 MPa)

V=5783 kN (7.1 MPa)


Yie

ld s

he

ar

forc

e (

kN

)

Max 95% Max 103% Max 89%

67% 67% 67%

46% 46% 46% PROTA


0 200 400 600 800 1000 1200 1400


1

2

3

4K

eff

(kN

/mm

)

2224 kN

4004 kN

5783 kN

Effective Stiffness

Max 52%

Max 34%

Max 22%

PROTA


Post-Yield Stiffness

0 200 400 600 800 1000 1200 1400


1

1.5

2

2.5

3

Kd

(kN

/mm

)

2223 kN4004 kN5783 kN2nd cycle3rd cycle

Cycle v = 0.76

(mm/s)

v = 355

(mm/s)

v = 711

(mm/s)

v = 957

(mm/s)

v = 1270

(mm/s)

1 -9.7 -6.2 -12.0 -6.6 -4.8

2 -4.8 -6.1 -15.8 -10.8 -6.9

3 -6.8 -6.5 -13.4 -10.5 -6.8

Max reduction (%) of

Kd due to increasing VL

Max 60%

Max 50%

Max 40%

PROTA


2000 2500 3000 3500 4000 4500 5000 5500 6000

Vertical load (kN)

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

dam

pin

g (

%)

1st cycle

2nd cycle

3rd cycle

Damping ratio

0 1 2 3 4

Cycle

0.9

1

1.1

i/2

0.762 mm/s

355.6 mm/s

711.2 mm/s

957.6 mm/s

1270 mm/s

Max VL 13% Max 29% - 19% - 14% PROTA


Model w/o velocity

and repetition of

cycles effects

Model

Experimental

F1+F2

x

F1+F2

x

Model with velocity

and repetition of

cycles effects PROTA


DEGRADATION OF THE RESPONSE OF

ELASTOMERIC ISOLATORS DUE TO TEMPERATURE

IN PROGRESS:

PROTA


Lead Rubber Bearing (Square Type) by OILES Corp.

Spec.

- 900mm x 900mm

- Lead Plug (4 pcs)

- NR (G0.4 N/mm2)

- S1:39.1

- S2:5.0

Test Program

-Vert. Stress : 10 N/mm2

-Vel. 1.5 cm/s -Sine wave

Bi-directional behavior of Lead Rubber Bearing

PROTA


1 2

3 4

Oval orbit（400%x200%）

PROTA


LRB-S-900 #2γ=400×200%（複合加力）

1000kN

Single direction Bi-directon (Multi orbit)

LRB had very stable characteristic under 400%x200% multi excitation test.

Longitudinal direction

Lateral

direction

長辺方向長辺方向

①

②

③

④

⑤

⑥

⑦

楕円加力

長辺/短辺：2/1

複合加力

長辺/短辺：2/1

①

③

②

長辺方向

短辺方向

一方向加力

長辺/短辺：1/0

①②

長辺方向長辺方向

①

②

③

④

⑤

⑥

⑦

楕円加力

長辺/短辺：2/1

複合加力

長辺/短辺：2/1

①

③

②

長辺方向

短辺方向

一方向加力

長辺/短辺：1/0

①②

Lat.=

+/-200%

Long.=+/-400% Long.=+/-400%

LRB-S-900 #1γ=400% (一方向加力)

-3000

-2000

-1000

0

1000

2000

3000

-750 -500 -250 0 250 500 750

Horizontal Displacement (mm)

Hroizontal Force (kN)

PROTA


SLIDING CONCAVE SPHERICAL

SURFACE IN STAINLESS STEE L

STEEL SLIDER

SLIDING POLYMER

COMPOSITE LINER

STEEL PLATE WITH

HOUSING FOR THE

SLIDER

FRICTION PENDULUM

PROTA


THEORY:

Restoring Force: F =W

Ru+ sign(v)mW

Kra=W/R

F

u

mW

2mW

T = 2π√(R/g)

PROTA


F

FV

G

Concave

surface Articulated

slider

Housing

plate

N

mN O

Self lubricating

bearing material

x

R

1

y b

M=F/b

Y=Fb/N

=y/R

X=Rsin(1-) F

PROTA

Caltrans Seismic Reponse Modification Device Test Facility SRMD

0

1

2

3

4

5

6

7

8

0 10 20 30 40 50 60 70p (MPa)

Kra (

KN

/mm

)

15 MPa (1st cycle ) 15 MPa (2nd cycle )

30 MPa (1st cycle) 30 MPa (2nd cycle)


trend line (1st cycle) trend line (2nd cycle)

theoretical

0

1

2

3

4

5

6

7

8

1 10 100 1000V (mm/s)

Kra (

KN

/mm

)

15 MPa (1st cycle ) 15 MPa (2nd cycle )



theoretical

Disagreement not exceeding 7%, 5% and

16% for the three increasing vertical load

cases, respectively

Kra=W/R

PROTA


LOAD EFFECT reduction of the friction

coefficient at increasing

applied loads

CYCLING EFFECT reduction of the friction

coefficient with repetition

of cycles

VELOCITY EFFECT variation of the friction

coefficient with the

velocity of motion

VARIATION OF FRICTIONAL CHARACTERISTICS:

BREAKAWAY EFFECT increase of coefficient of friction

at the beginning or at each inversion of the motion PROTA


EDC = -0.159p2 + 15.595p

R2 = 0.4482

0

100

200

300

400

500

600

0 10 20 30 40 50 60 70

p (MPa)

ED

C (

kN

m)

15 MPa 1st cycle 15 MPa 2nd cycle



dispersion of

experimental

values due to

velocity and

cycling effects

0

100

200

300

400

500

600

0.1 1 10 100 1000

V (mm/s)

ED

C (

kN

m)




Variation of EDC with respect to applied pressure p and peak velocity V

PROTA


fw = 0.103e-W/12300

R2 = 0.984

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0 2500 5000 7500 10000 12500 15000W (kN)

f w (

-)

fW W( ) = ms0e-W/Wref

LOAD EFFECT

m W,c,v( ) = fW W( ) × fc c( ) × fv v( )MODEL:

PROTA


VELOCITY EFFECT

fv v( ) =g + 1-g( )e-v /vref Max increase ~40%

PROTA


c t( ) =2

ap 2A2Wv2 dt

t0

t

ò fc c( ) = e- c cref( )

b

REPETITION OF CYCLES EFFECT

PROTA


Friction reduction for repetition of cycles effect PROTA


0

100

200

300

400

500

600

0.1 1 10 100 1000

V (mm/s)

ED

C

15 MPa 1st cycledegradationdegradation refinedno degradation

0

100

200

300

400

500

600

0.1 1 10 100 1000

V (mm/s)

ED

C

15 MPa 2nd cycledegradationdegradation refinedno degradation

0

100

200

300

400

500

600

0.1 1 10 100 1000

V (mm/s)E

DC


0

100

200

300

400

500

600

0.1 1 10 100 1000

V (mm/s)

ED

C


0

100

200

300

400

500

600

0.1 1 10 100 1000

V (mm/s)

ED

C


0

100

200

300

400

500

600

0.1 1 10 100 1000

V (mm/s)

ED

C


Experimental and predicted EDC values versus

peak velocity V (top row=1st cycle, bottom row=2nd PROTA


MULTI-DIRECTIONAL TESTS

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

-250 -150 -50 50 150 250

u (mm)

m (

-)

monodirectional test - long - p=30MPa

bidirectional test - long - p=30MPa

increased cycling +

diagonal sliding

effects

increased

cycling effectdiagonal

sliding effect

-250

-200

-150

-100

-50

0

50

100

150

200

250

-250 -200 -150 -100 -50 0 50 100 150 200 250

ulong (mm)

ula

t (-)

Increased cycling+

diagonal sliding

effects

increased cycling diagonal sliding

Cloverleaf motion

PROTA


During the applied bi-directional motion the slider moves along

directions not parallel to the longitudinal and lateral axis of the

device. The frictional force developed in longitudinal and lateral

direction is only a component of the force generated along the

diagonal direction. For this reason, the bi-directional experimental

cycles indicate an apparent reduction of the frictional force with

respect to the mono-directional results.

DIAGONAL SLIDING EFFECT

INCREASED CYCLING

Due to the manufacturing process of the sliding surfaces, the

friction coefficient depends on the direction of motion.

ASYMMETRY EFFECT

PROTA


-400

-300

-200

-100

0

100

200

300

400

-300 -200 -100 0 100 200 300

Displacement (mm)

Forc

e (

kN

)

BI-DIRECTIONAL

MONO-DIRECTIONAL

The mono-directional test over-estimate the dissipative capacity

with the consequence of possible exceedence of design

displacements. PROTA


DOUBLE PENDULUM

D.M. Fenz, M.C. Constantinou, 2006 PROTA


PROTA


PROTA


PROTA


-150

-100

-50

0

50

100

150

0 2 4 6 8 10 12 14

t (sec)

d (m

m)

NO VERT.

VERT.

EFFECTS OF VERTICAL COMPONENT OF MOTION

SAME RESIDUAL DISPL.

LARGER DISPL.

SMALLER PERIOD

PROTA


-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

-120 -70 -20 30 80 d (mm)

F/W

(-)

NO VERT.

VERT.

EFFECTS OF VERTICAL COMPONENT OF MOTION

HIGHER OSCILLATION LARGER DISPL.

PROTA


Vincent Thomas Bridge-

Problems of durability of viscous dampers

PROTA


Wear issues in dampers: asymmetric bearing wear (top right) due to

side loading. Excessive galling and scoring on piston rod (bottom) PROTA


Problems of durability with viscous dampers

PROTA


NEW ISSUES:

INSPECTION OF DEVICES IN SERVICE

INSPECTION CRITERIA and METHODS (NDE, MONITORING) etc.

MAINTENANCE AND RETROFIT

CRITERIA AND METHODS

PROTA


Conclusions

The technology of isolation confirmed his potential also

with the support of extensive experimental campaigns

The designer MUST assume a proactive role in the

coordination of the validation process of a device

performance.

Questions about durability and maintenance of

anti-seismic devices need urgent answers

PROTA

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Characterization of the performance and - Prota … · Characterization of the performance and ......

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