the university of adelaide earthquake engineering in australia – international collaboration and...

The University of Adelaide

Earthquake Engineering in Australia – International Collaboration and Future Directions

Mike Griffith

President, Australian Earthquake Engineering Society

Associate Professor, University of Adelaide


Introduction

Australian Earthquake Hazard & Seismic Risk:

•Effective PGA design coefficient = 0.08g ± 50%

•Population concentrated in capital cities, with nearly 50% living in either Melbourne or Sydney

•Use of unreinforced masonry (URM) construction widespread, especially for house and 2- to 4-storey apartment dwellings

•Commercial buildings typically have long clear spans with gravity frames and lift core shear walls to resist e/q


Research Results (to date):

•R/C frames should survive the 500-year design magnitude earthquake (DME) event by virtue of elastic over-strength but limited ductility exists to cope with much larger event

•URM construction can survive a DME if it is well designed and constructed; otherwise major damage is likely and no real capacity to survive bigger event.


Relationship between PGA and annual probability of exceedance for different seismic regions

(from Paulay and Priestley, 1992).


Shake-table test of 1/5-scale 3-storey r/c frame


International Collaborations

•International collaborations are critical for Australian researchers to advance the practice of earthquake engineering within Australia

•Provides much need added value to the limited amount of money available for this research from Australian sources

•3 collaboration that I have been involved with will be described here


International Collaborations (cont.)

•Seismic behaviour of R/C Frame + URM Infill (conducted at ELSA at JRC in Ispra with Dr. Pinto)

•Seismic retrofit of R/C columns (with Prof. Monti, Univ. of Rome)

•Seismic behaviour of URM buildings (with A.Prof. Magenes at Univ. of Pavia)


Seismic behaviour of R/C frames with URM infill walls


RC frame + URM infill


Storey shear versus drift for ELSA test frames (from Pinto et al, 1999).

S_D Floor_1

-1.50 -1.20 -0.90 -0.60 -0.30 0.00 0.30 0.60 0.90 1.20 1.50

-1000

-800

-600

-400

-200

0.00

200

400

600

800

1000Oy

Ox

Storey Drift (%)

Shear (kN)

Infilled Frame

Bare Frame


Deflection (% of height)

Load (kN)

-4.0

150

3.0

-150


Load (kN)

-4.0

150

3.0

-150


Load (kN)

-4.0

150

3.0

-150


Load (kN)

-4.0

150

3.0

-150

(a) Storey shear versus drift (no infill) (b) Storey shear versus drift (with infill)

Test results for ½-scale r/c frame subject to cyclic loading (from Griffith and Alaia, 1997).


A

A

roller support

pinsupport

variable lateral load F

axialload N

stubcantilever column cantilever column

LVDT B

LVDT A

LVDT C

0

10

20

30

40

0 20 40 60 80 100 120

Lateral displacement at top(mm)

Late

ral f

orce

at t

op (

kN)

-40

-30

-20

-10

0

10

20

30

40

-60 -40 -20 0 20 40 60

Lateral displacement at top (mm)

Late

ral f

orc

e at

top

(kN

)

Adelaide test results for 200x200mm R/C column (Wu et al, 2001)

2.5% drift


Seismic retrofit of R/C columns


(a) ductility retrofit of RC columns (b) strength + ductility retrofit of RC columns

Seismic retrofit of columns in ELSA frames


steel plate AA

20080

60

60

A-A

steel plate

12 threaded rod bolts

950

290

150 100 100 100 100 100 100 100

Strain gaugeson both sides

70

-50-40

-30-20

-100

1020

3040

50

-90 -60 -30 0 30 60 90

Lateral displacement at top (mm)

Late

ral f

orce

at t

op (k

N)

3ACR

4ACP6

Details of partial interaction plating

Cyclic test results

Column retrofit research at Adelaide(from Wu et al, 2003)


(a) 3ACR (=-56~65mm) (b) 4ACP6 (=-82~150mm) (c) 4ACP6 at +150mm

Damage to retrofit columns during and at conclusion of testing(from Wu et al, 2003)


Seismic behaviour of URM buildings


Shaking Table Test Set-up


Shaking Table Test of URM Wall


Experimentalnon-linear

Tri-linearmodel

1

2

U

Force

1

2

Fmax

Force-displacement relationship of URM wallin vertical bending (Doherty et al, 2002)


0.00

1.00

2.00

3.00

4.00

5.00

0.0 0.2 0.4 0.6 0.8 1.0

MAX / u

Sd(T

1) /

M

AX

Wall 1

Wall 1a

Wall 2a

Wall 3a

Wall 4

Wall 4a

Wall 5

Wall 6

Response spectrum predictions using T1 values for period


0.00

1.00

2.00

3.00

4.00

5.00

0.0 0.2 0.4 0.6 0.8 1.0

MAX / u

Sd(T

2) /

M

AX

Wall 1

Wall 1a

Wall 2a

Wall 3a

Wall 4

Wall 4a

Wall 5

Wall 6

Response spectrum predictions using T2 values for period


Displacement range Err(T1) Err(T2) Err(TS) -17% 125% 61% mean

50%U > MAX > 0

24% 152% 47% st. dev. -49% 2% 51% mean

MAX > 50%U

19% 25% 74% st. dev. -53% -5% 47% mean

MAX > 70%U

19% 20% 69% st. dev.

Mean and standard deviation of the error Err(T)=[Sd(T)- max]/max

using different definitions of effective period, for all walls and allaccelerograms (from Griffith et al, 2003).


Future Directions

•R/C structures and URM buildings are the primary types of construction of interest w/r E/Q loading

•Research priority should focus on 2 broad areas:

assessment of seismic capacity

development of appropriate retrofit strategies


Closing Remarks•E/Q hazard in much of Europe, North America and Asia is similar to that in Australia.

•Also many common forms of construction materials and methods

•Hence, closer international collaborations can realistically be used to:

tackle common issues

build on experience and expertise of researchers concerned with high seismicity


Acknowledgements

• R/C Frame plus URM infill research at ELSA with Dr Pinto supported by ICONS TMR-Network research program grant.

• Seismic behaviour or URM buildings (with Magenes at Univ. of Pavia) supported by INGV-GNDT 2002-2003 framework program and the Aust. Research Council

• Seismic retrofit of RC columns research (with Monti at Univ. of Rome) supported by an ARC International Linkage grant.


0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14

Effective Peak Shaking Table Acceleration (EPA), g's

Nor

mal

ised

Bas

e S

hear

(V

/W)

Shake table test results for 1/5-scale 3-storey r/c frame


Static push-over test of 1/5-scale 3-storey r/c frame (experiment and analysis)

(a) (b) (c) (d)

V=0.31W V=0.34W V=0.36W V=0.37W

(a)

(c) (d)(b)

Roof Displacement, mm

V/W

0

0.1

0.2

0.3

0.4

0 5 10 15 20

Experiment

Static PushOver

Drift = 1.5% 2.5%

the university of adelaide earthquake engineering in australia – international collaboration and...

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drift slide

eq slide

pavia slide

storey rc frame slide

table test of urm wall