damage evaluation analysis

8/12/2019 Damage Evaluation Analysis

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Hikaru NAKAMURA

Minoru KUNIEDAYoshihito YAMAMOTO

NAGOYA UNIVERSITY, JAPAN

DAMAGE EVALUATION ANALYSIS ANDREPAIR/STRENGTHENING METHOD

OF CONCRETE MEMBERSDUE TO EARTHQUAKE

a .concept 14 : 4 th ASEP22 - 24 M a y 2014Century Pa rk Ho te l M in i la


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CONTENTS

Effect of Big Earthquake fromEconomic point of view

Damage and Restoration Process of

Damaged Concrete Structures

Damage Evaluation using F.E.M

Damage Evaluation using RBSM

Rapid Repair/Strengthening Methodusing UHP-SHCC


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Recent strong earthquakes concretestructures were damaged

1: Kobe, 95.1.17, M7.2

2: Tottori,00.10.6, M7.3

3: Geiyo, 01.5.24, M6.7

4: South of sanriku-oki, 03.5.26, M7.1

5: Miyagi-oki , 03.7.26, M6.2

6: Tokachi -oki , 03.9.26, M8.07: Niigata-ken chuetsu, 04.10.23, M6.8

8: fukuoka-oki, 05.3.20, M7.0

9: Noto Hanto, 07.5.25, M6.9

10: Niigata-ken chuetsu-oki,

07.7.16, M6.611: Iwate-Miyagi nair iku, 08.6.14, M7.2

12: Higashi Nihon, 11.3.11, M9.0

After Kobe Earthquake, the concrete structures have beendamaged due to several earthquakes in Japan.

map of recent strong earthquakes that concrete structures were damaged

13

4

5

6

2

8

7109

11

It is difficult to avoid damage of concrete structures perfectly due to strong earthquake.We have to consider the influence of damage of concrete structures.

12


4/47

Change of number of dead persons andeconomy loss

Change of Economic Loss and Casualities by E.Q. Disasters in the World

0

100,000

200,000

300,000

400,000

500,000

600,000

1900-

1909

1910-

1919

1920-

1929

1930-

1939

1940-

1949

1950-

1959

1960-

1969

1970-

1979

1980-

1989

1990-

1999

2000-

2005

0

10

20

30

40

50

60

70

80

us$ Billions

EconomylossDearthperson

Dearthperson

Economy

loss

Economy loss increase from 1970. This is the reason that society develop highly and social system connect

with many parts. If once some parts of social system break, it influence to total system and economy loss.

Important point is to decrease economy loss in order to keep social

system as well as to decrease number of dead persons.


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Economy loss forecast due tofuture earthquakes

Probability map of earthquake

Economy loss

(trillion US$)(direct damage)

Probabilityduring 30years

Inland

earthquake inTokyo

112(6.7) 70%

Tokai,Tonankai and

Nankaiearthquake

2.2(1.7)

70%

Economy loss forecast and occurrence probability

Direct damage

Indirect damageDecrease of damage

Rapid Restoration

Damage prediction and evaluation are important


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CONTENTS








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Seismic Performance

SeismicPerformance 1

Function of the structure during an earthquake is maintained,and the structure is functional and usable without any repairafter the earthquake.


Function of the structure can be restored within a short periodafter an earthquake and no strengthening is required.


There is no overall collapse of the structural system due to anearthquake even though the structure does not remainfunctional at the end of the earthquake.

Seismic performance is classified into 3 cases

The damage is allowable for strong earthquake.Performance 1 : serviceabilityPerformance 3 : safetyPerformance 2 : serviceability and restoration ability

from social and economic points of view

Concept

make clear damage for restoration process

definition of seismic performance in JSCE specification.


8/47

The severe damages were observed in 5 onestory RC viaduct of Tohoku Shinkan-senconstructed in 1977 to 1978.The feature of damages was that the endcolumns are mainly damaged. The endcolumns failed in shear with the spalling of

the cover concrete.

Damage of columns of RC elevated bridges of Shinkan-sen due toSouth of Sanriku-Oki Earthquake at 2003

damaged one story 4 spans RC elevatedbridges of Shinkan-sen

Damage and Restoration Process


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Restoration procedure was (1) injection of epoxy resin to cracks, (2)

restoration of cross section by shrinkage compensating mortar, and(3) steel jacketing.

Restoration finishedonly in 3 days

May 26: earthquake occur

May 27: shinkan-sen start to drive slow speed

May 29: shinkan-sen drive normal speed again

process of repair and strengthening of damaged structure



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In the case, the damaged structures were strengthened by RC jacketingafter restoration of cross section.

Tokachi-Oki Earthquake on September 26, 2003


The spalling of the concrete cover and buckling of the longitudinal

re-bars occurred at cut-off plane of the longitudinal re-bars.


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Damage of Shinkansen bridge due to Higashi NihonEarthquake

Restoration procedure was (1) chipping of cover concrete around spalling part,(2) arrangement injection tube, (3) arrangement web reinforcement, (4)

restoration of cross section by shrinkage compensating mortar, and (5)injection of resin to cracks

Restoration finished only in 8 days

Spalling of cover concrete at cut-off plane


the restoration ability is very

important based on social and

economic points of view

how to verify the damage for

restoration ability before

earthquake and how to restore inshort time after earthquake
http://www.jreast.co.jp/e/index.htmlhttp://www.jreast.co.jp/e/index.html


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CONTENTS








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In Past

two decades

constitutive

models

numerical

algorisms

analytical

theories and modeling

Nonlinear analysis, especially

F.E.M for concrete structureshas advanced remarkably

Nonlinear analysis, especially F.E.M. become

a most powerful tool to verify

the required performance of concrete structures


14/47

Evaluation of Seismic Performance

Floor

Footing

Shaking Table

Spring

Dynamic test for 5 stories

RC building0 2 4 6 8 10 12 1

-1.2

-0.8

-0.4

0

0.4

0.8

1.2

Time [sec]

Accelerator[g] V03S02 [1.35g]

Max. Acc. is about 1.0g

simulation result of dynamic test for 5stories RC bui ld ing in order toevaluate the seismic performance


15/47The displacement response can be simulated accurately.


16/47

Results of F.E.M


17/47

Can nonlinear analysis simulate damage?

Compression failure of concrete

Buckling of re-bars

Typical damage in flexure

Damage Local behavior

Localized area

Local strain

Can nonlinear analysis simulate local behavior ?

we can simulate global structural behavior using nonlinear analysis


18/47

10 20 30 40 50 60

20

40

60

80

0

Displacement (mm)

Load(kN)

10 20 30 40

100

200

0

Displacement (mm)

Load(kN)

-0.0794-0.0588-0.0382

0.0030-0.0176

-0.1000-0.0308-0.0216-0.0124

0.0060-0.0032

-0.0400

B series

Compressive strain distribution Compressive strain distribution

A series

Problem of F.E.M


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CONTENTS








20/47

RBSM (Rigid Body Spring Model)

This model can evaluate the effect of

bending and torsional moment

automatically without rotational springs.

Vertex

Gravity pointIntegral point

For reduction of

elements dependency

One integral point hastwo kinds of springs

(normal/shear)

Cracks are expressed by the failure of

springs and cracking behavior can be

shown directly.

Analytical model is

divided by 3-D Voronoi

particles

A number of springs are set inboundary of each surface.

RBSM is analytical model to simulate structural behavior by springsbetweenRigid Bodies.


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Concrete Material Model

Concrete Models (Yamamoto et al. 2008)

no softening part

is modeled in

compression

kn k t

kn k t

Normal spring

Shear spring


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Reinforcement Model

Reinforcement : beam element

beam nodes : attach to the concrete particlesthrough zero-size link element

stress strain relationship : bi-linear model.

Bond property: introduced into the shear springof linked element

fy

fy

Stress strain relationship

Zero sizelinkelement

Beamelement

modeling of reinforcement


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Results of RBSM

(b) 2700kN

0.01mm 0.1mm

0 2 4 6-2

-1

0

1

2

Time (s)

Displac

ement(mm)


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Uni-axial Compression Test

Strain distribution along the height and deformation

(The strain distributions are measured by using acrylic bar arranged inside specimen)

Uni-axial Compression test carried by

Fujikake et al. having diameter of 100mm

and height of 200mm and 400mm aresolved by RBSM.

Reasonable simulation of axial local strain and localized area with failure mode.

0.002 0.004 0.006 0.008 0.

10

20

30

40

50

0

Stress(N/mm2)

Strain

Analysis (200mm height)test (200mm height)Analysis (400mm height)

test (400mm height)

Stress-Strain relationship

a

b

c

d

a b c dTest Analysis

5000 10000 15000

100

200

300

400

0

Distancefromb

ottom(mm)

Local strain ()

1.0max

0.8max

0.6max

0.4max0.2max

5000 10000 15000

100

200

300

400

0

Distancefromb

ottom(mm)

Local strain ()

1.0max

0.8max

0.6max

0.4max

0.2max

The stress strain relationship agree

significantly well with the test for different

shape.


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Damage evaluation of Flexure Failure Beam

Analytical model with Voronoi diagram

Load displacement relationship

20 40 60

10

20

0

Load(kN)

Displacement (mm)

Test Analysis

d

c

d

c

PC barcantilever type RC beam failed in

compression flexural mode

Results of canti lever type RC beam failed in compression flexural mode

Crack propagation behavior at peak and post peak

RBSM can simulate global behavior,

the advantage is that it can show the

realistic crack propagation behavior


26/47

RBSM is useful method to simulate local damage of concrete structures

as well as cracking

Flexure Failure test of Beam

Longitudinal compressive strain distributions at failure zone

(a) Test result

strain

0 100 200 300 400 5000

5000

10000

15000

0 100 200 300 400 5000

5000

10000

15000 0.7Pmax

Location (mm)

strain

Location (mm)(b)Analytical result

0.8Pmax

0.9Pmax

PmaxPmax

0.9Pmax0.8Pmax0.7Pmax Similar

strain

distribution

Pmax 0.8Pmax (Post-peak) 0.6Pmax (Post-peak)

Deformation in compression failure zone Realistic failure behavior


27/47

Damage Evaluation under Cyclic Loading

600150

640 110

[Unit:mm]

115

200160

600 640 110

Skeleton curve

Dimension of simulated RC column

Analyt ical model

0 5 10 150

10

20

30

[mm]

[kN]

Displacement (mm)

Load

(kN)

3y

The feature of the specimen is shear

failure after yielding of longitudinal re-

bars. This type of failure is often

observed with diagonal cracks in the

case of lower web reinforcement

subjected to cyclic loading.


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Simulation Results of RC Column

flexural behavior is dominant

1y

2y

3y

-30-25-20-15-10 -5 0 5 10 15 20 25 30-30

-20

-10

0

10

20

30

[mm]

[kN]

Displacement (mm)

Load

(kN)

monotonic(analysis)cyclic (analysis)test

Diagonal crack develop

Shear deformation is dominant withreduction of load carrying capacity


29/47

-20 0 20-30

-20

-10

0

10

20

30

[mm]

[kN

]

Simulation Results of RC Column

Displacement (mm)

Load

(kN

)


30/47

Effect of Web Reinforcement

-20 0 20-30

-20

-10

0

10

20

30

displacement[mm]

load[kN]

Displacement (mm)

Load

(kN

)

The shear failure after yielding can be

prevented by arrangement of sufficient

amount of web reinforcement.Design code require suff icient amount

of web reinforcement in order to fail in

flexural.

Web reinforcement of 0.46%


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CONTENTS







Requirement of Rapid


32/47

Requirement of Rapid

Repair/Strengthening Method

Disadvantages;

Much cost Many construction processes

Development of Rapid Recovery Technique


33/47

Development of Rapid Recovery Technique

by using repair material, UHP-SHCC

Process of repair for damaged structures

Damaged part of

concrete structure. Very easy.Spraying UHP-SHCC only! !

Advantages:

Without any other construct ion processesand heavy construction machine

No addit ional reinforcement

No framework

No additional cross section

Cementitious material is easy to stock and repair


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Ultra High Performance-Strain Hardening Cementitious Composites

What is the UHP-SHCC ?

PE fiberSilica fume water cement Fine aggregate

Cement Silica sand

PE fiberSilica fume

High strength

High ductili ty

High permeabil ity

Wh i h UHP SHCC ?


35/47

Multiple fine cracking.


Compressive strength (MPa) Tensile strength (MPa)

UHP-SHCC 80~90 7~8

Normal Concrete 25~35 2~3

0

2

4

6

8

10

12

14

0 1 2 3 4 5

Strain(%)

Stress(MPa)

Increase fiber content

Crack width is less than 0.05mm

strengthening material

Wh t i th UHP SHCC ?


36/47


Penetration of chlor ide ion after specimens merged

in salt water of 10%(EPMA)

UHP-SHCC normal concreteW/C=56%

mm2mm

W/B is about 20%

Mixing of silica fume

High permeabil ity

Repair material with coating effect

Wh t i th UHP SHCC ?


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Spraying method

Reduce construction work


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Initial loading

Treatment

Repair

Second loading

Curing

Flow of experiment.

A cyclic loading (namely initial loading)

was carried out for RC column designed

by Japanese code.

450 450400

22@80=1760

850

850

4

00

2500

40040

4@80=320

Cross Section

Longitudinal Reinforcement

Hoop Reinforcement

(Unit:mm)

Axial Loading(1N/mm2)

Outline of experimental specimen

Procedure of Experiment

f


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Initial loading

Treatment

Repair

Second loading

Curing

Flow of experiment.

Concrete structure was damaged.

(Spalling of cover concrete andbuckling of longitudinal reinforcementwere observed).

Spalling of cover concrete.

Buckling of longitudinal

reinforcement.


P d f E i


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Treatment

Repair

Second loading

Curing

Flow of experiment.

Spalling of cover concrete. Cleaned up!!

Concrete brocks were cleaned up by hand

work and water spraying was also appliedto prevent the water absorption of repair

material itself.

Init ial loading


P d f E i t


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Init ial loading

Treatment

Repair

Second loading

Curing

Flow of experiment.

UHP-SHCC: Spraying technique. PCM: Plastering technique.

(most popular to repair)

Three repair materials were used.

Spraying technique

UHP-SHCC

Plastering technique.

PCM


P d f E i t


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Init ial loading

Treatment

Repair

Second loading

Curing

Flow of experiment.

Curing days of repair materials

and repaired specimens:

5~10 daysVery short!!

RAPID RECOVERY TECHNIQUE!!


Load Displacement Curves


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Load- Displacement Curves

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

-150

-100

-50

0

50100

150

200

250

Displacement (mm)

Load(kN)

Initial loading

PCM specimen-150 -100 -50 0 50 100 150-250-200

-150

-100

-50

0

50100

150

200

250

Displacement (mm)

Load(kN)

Initial loadingUHP-SHCC specimen

PCM specimen: Peak load and ductility were lowerthanthat of init ial loading.

UHP-SHCC specimen: Peak load and ductility were

higher than that of init ial loading.

PCM specimen UHP-SHCC specimen

F il B h i (S d L di )


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Failure Behavior (Second Loading)

Front view (Final) Side view (Final)

(PCM) (UHP-SHCC)

Front view (Final) Side view (Final)

Spalling of PCM

Splitting cracks along longitudinal reinforcements

PCM specimen (second loading)

UHP-SHCC specimen (second loading)

NOT spalling of UHP-SHCC!

NOT splitting cracks along longitudinal reinforcements!

CONCLUSION


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CONCLUSION

It is difficult to avoid the damage of concrete structures

due to big earthquake. Therefore, the damage should beevaluated directly by the analysis to verify the restoration

ability from social and economic points of view.

Requirement against advanced nonlinear analysis is tosimulate local behavior reasonably as well as global

behavior such as load displacement relationship.

As an advanced simulation method, the applicability ofRigid-Body-Spring Model (RBSM) was presented. It

showed high potential to simulate the realistic behavior of

concrete structures directly such as local damage as well

as load-displacement relationship until failure stage.

CONCLUSION


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CONCLUSION

The rapid jacketing technique was developed which

involves only spraying of UHP-SHCC. Any formwork andadditional reinforcement are not required. It might be helpful

to reduce a construction process that is corresponding to

reduction of cost.

It was confirmed experimentally that the developedtechnique using UHP-SHCC improve not only ultimate load

but also ductility of recovered specimen. It seems that the

prevention of buckling of longitudinal reinforcement, which

was constrained by UHP-SHCC, imparts the mechanical

improvement to the column specimens.


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Thank You Very Much

for Your kind Attention !

damage evaluation analysis

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