SHAPE MEMORY ALLOY AND HIGH-PERFORMANCE GROUT IN EARTHQUAKE-RESISTANT BRIDGES- FROM RESEARCH TO IMPLEMENTATION

M. Saiid Saiidi, University of Nevada, Reno

Seismic performance objective for standard bridges: No Collapse

“Failure” “Success”

Damaged bridges have to be closed

-Ambulances and fire trucks -Other emergency response vehicles -Public transportation -Major economic impact (local, maybe global)

Serviceability after earthquake:

Minimize permanent drift and damage

Performance-based design

Advanced materials/details

Shape memory alloys/ductile concrete

Columns w/ built-in elastomeric pads

Fiber-reinforced polymers

Evolution in SMA (Nickel Titanium) Use/Research

Also military applications

Superelastic Shape Memory Alloy

Superelastic

response

Shape memory effects

First developed in 1932

NiTi SMA developed in1962

SMA bars

Beam Tests at UNR

0

2

4

6

8

10

12

14

16

18

0.0 0.2 0.4 0.6

Deflection (inches)

Loa

d (K

ips)

0

9

18

27

36

44

53

62

71

80

0.00 5.08 10.16 15.24

Deflection (mm)

Loa

d (K

N)

0

2

4

6

8

10

12

14

16

0.0 0.2 0.4 0.6 0.8

Deflection (inches)

Loa

d (K

ips)

0

9

18

27

36

44

53

62

71

0.00 5.08 10.16 15.24 20.32

Deflection (mm)

Loa

d (K

N)

SMA Reinf. Beam

Steel Reinf. Beam

Load vs Deflection

Cyclic Load Tests of Columns

Objectives: (1) Determine residual displacement recovery of

SMA reinforced columns under load reversals. (2) Study effect of using ductile concrete on

damage.

>> 3 columns: Conventional RC, SMA/regular concrete, SMA/ECC (Engineered cementitious composite)

ECC

Polyvinyl Alcohol Fiber 0

200

400

600

800

1000

0 0.5 1 1.5 2 2.5 3 3.5 4

Strain (%)

Te

ns

ile

Stre

ss

(p

si)

0

1.4

2.8

4.2

5.6

7

Te

ns

ile

Stre

ss

(M

Pa

)

Conventional

Concrete

ECC

Conventional SMA/ECC

10% Drift

0

1

2

3

4

5

6

7

8

0 2 4 6 8 10 12 14

Maximum Drift Reached (%)

Re

sid

ua

l D

rift

(%

)RSC

RNCRNE Through -12% Drift

Linear (RSC)Linear (RNC)

Linear (RNE Through -12% Drift)

Conventional

82%

SMA/Conc.

27%

SMA/ECC

14%

Conventional

SMA/ECC Repair

Shake Table Tests of Columns

4-Span Bridge Model w/ Advanced Details

SMA/ECC

PT Elastomer

Total model length= 35 m Top Plastic Hinges: Conventional RC

Damage: Final Motion

TOP

BOT.

SMA/ECC

RC

Accelerated bridge construction

8% Drift

To be replaced w/ SMA/ECC

Precast Columns

30-mm SMA Bars

3-Span Bridge 33m; 54m; 33m

Single column piers with SMA/ECC

ABC

Square columns 1.5 x 1.5m

SMA/ECC Implementation: SR-99 Bridge in Seattle, Washington

SMA

Bars

Mild Steel

Spirals

SMA

Bars

Mild Steel

Bars

Couplers

Mild Steel

Bars

Mild Steel

Bars

SMA Connections

Longitudinal: Single Curvature

Transverse: Double Curvature

Pin

Column Deformations

Damage: “Rare” Earthquake

SMA Bent PT Bent Elasto Bent

TOP

BOT.

RC RC

SMA/ECC

Analytical Studies: Near-Fault EQ– Rinaldi (Northridge, 1994)

100% Rinaldi - RC Bridge

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-76

-51

-25

0

25

51

76

102

127

152

Dis

pla

cem

en

t (m

m)

All Bents

100% Rinaldi - PT bridge

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-51

-25

0

25

51

76

102

127

152

Dis

pla

cem

en

t (m

m)

All Bents

100% Rinaldi - SMA Bridge

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-102

-76

-51

-25

0

25

51

76

102

127

152

All Bents

100% Rinaldi - RC Bridge

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-76

-51

-25

0

25

51

76

102

127

152

All Bents

100% Rinaldi - Test Model

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-76

-51

-25

0

25

51

76

102

127

152

Dis

pla

cem

en

t (m

m)

ISO Bent

PT Bent

SMA Bent

100% Rinaldi - SMA Bridge

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-102

-76

-51

-25

0

25

51

76

102

127

152

Dis

pla

cem

en

t (m

m)

All Bents

100% Rinaldi - RC Bridge

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-76

-51

-25

0

25

51

76

102

127

152

Dis

pla

cem

en

t (m

m)

All Bents

100% Rinaldi - ISO bridge

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-76

-51

-25

0

25

51

76

102

127

Dis

pla

cem

en

t (m

m)

All Bents

100% Rinaldi - SMA Bridge

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 2 4 6 8 10 12 14 16 18 20

Time (sec)

Dis

pla

cem

en

t (i

n)

-102

-76

-51

-25

0

25

51

76

102

127

152

Dis

pla

cem

en

t (m

m)

All Bents

Residual drift Ratio= 3%

Observations

All three details effective in minimizing residual displacements

Only minor damage in SMA/ECC plastic hinges

Only minor damage in elstomeric plastic hinges

Analytical studies revealed major reduction

in residual drift of the bridge when SMA/ECC or pot-tensioned elastomeric pads were used.

2 - ABC Connection Details (Cont’d)

Substructure connection examples (Cont’d) :

III. Precast columns with extended bars inserted in grouted metal sleeves or couplers

5 - ABC Connection Research (Cont’d)

Successful emulative ABC connections

Precast columns embedded in footings/cap beams

Large diameter bars embedded in corrugated ducts

Various standard couplers

Various methods to convert multi-girder pier cap connections to integral pier caps

Research continues