JST Research MeetingD li 12 N b 2010Dalian, 12 November 2010

Life‐cycle management (LCM)and

its international standardizationits international standardization

Professor, Hokkaido University, Japan

Hiroshi YOKOTA, PhD, PE

1

Life‐cycle of structure

Planning Requirements• Function

Basic design

Detail design Verification

• Function• Performance

1‐2 years

Detail design

Execution

Verification

Materials/Construction• Selection• Production

( l f )

1‐5 years

Maintenance • Assessment (incl. verification)• Evaluation• InterventionS i ti

50‐100 years

Replacement

• Scenario correction50 00 yea s

2

ISO’s for concrete structures

Design Maintenance Lifecycle Management

Design Code

ISO 2394Maintenance

ISO/CD 16311

Role, Function, Activity, Importance

ISO 19338

ISO 15673

ISO/DIS 28841

/

ISO 13822 LCC, LCA, etc.Life‐cycle scenarioLink

ISO/DIS 28841

ISO/DIS 28842

ISO/WD 16204(Durability ‐ service life design)

Assessment, Performance

(Durability  service life design)

Environmental t

Mainte‐nancePlmanagement

ISO/CD 13315Plan

Scenario

DB

3

Performance (Safety, Serviceability, etc.)

Initial value

Minimum value

Initial level?Time

Design service life

STRATEGYSTRATEGYPerformance (Safety, Serviceability, etc.) Maintenance scenario?

STRATEGYSTRATEGYInitial value

Minimum value

Time

Design service life4

Life‐cycle management systemi f

Maintenance planDesignScenario for performance guarantee

Periodic inspection Input/Reference

Service periodUsage

p

Assessment and Prediction

p

DesignEnvironment

Assessment and Prediction

Performance Database・Inspection・Prediction

Input/Reference

Present Time

・Prediction・Intervention

Service life

Method of interventionInput/Reference

Future plan

Scenario correction 5

New Work Item Proposal

ISO/TC71/SC7 on 21 September at Cartagena, Colombia

Scope of proposed projectThis is to propose to prepare ISO document on life‐cycleThis is to propose to prepare ISO document on life cycle management of concrete structure including formulation of scenarios how structural performance of which would be guaranteed during the life span of the structure. 

6

New Work Item Proposal

Purpose and justificationConcrete structures should guarantee their structural performance over the required levels during their life spans. For this purpose, durability design including service life design and maintenance and repair workservice life design and maintenance and repair work have been installed.  However, the initial design and further maintenance strategy are not linked each other.  gyThere have been great needs of management methodologies to cover considering the structural performance during the whole life of structure.  This International Standard deals with the methodologies to formulate scenarios how structural performance wouldformulate scenarios how structural performance would be guaranteed and how prioritization would be made by using some indexes such as life‐cycle cost, 

7

g y ,environmental impact, etc.

Provisional table of contents

ISO/WD xxxxx Life cycle management of concrete structuresForewordIntroduction1 S1. Scope2. Normative references3. Terms and definitions4. Life cycle management elements

4 1 General requirements4.1 General requirements4.2 Target, tactics and strategy4.3 Manage information and decision-making index

LCC, NPV, LCCO2, Energy consumption, LIME (?)4 4 Implementation and operation4.4 Implementation and operation4.5 Checking and corrective action

5. Structure planning6. Material production (concrete production)7 Design and performance verification7. Design and performance verification

Performance of structure in combination with initial performance and performance recovery strategy during service lifeDurability (Service life design)Structural robustness redundancy and integrityStructural robustness, redundancy and integrity

8. Execution9. Performance assessment

Prediction based on assessment dataScenario correction

8

Scenario correctionDecision making for interventions

10. Replacement

ISO/TC59/SC14 Design Life (Secretariat: BSI)

ISO 15686 Buildings and constructed assets ‐ Service life planning 

Part 1: General principlesPart 1: General principles

Part 2: Service life prediction procedures

Part 3: Performance audits and reviews

Part 4: Data dictionary (TR?)

Part 5: Whole‐life costing

Part 6: Procedures for considering environmental impacts

Part 7: Performance evaluation for feedback of service life data from practice

Part 8: Reference service life and service life estimationPart 8: Reference service life and service life estimation

Part 9: Guide on service life declarations for building products

Part 10: Data requirements

Part 11: Terminology

9

Prediction of carbonation depth

ty dcbd （7.1.1）

yd : Carbonation depth ：Safety factor

Carbonation depth

cb：Safety factord：Design carbonation rated = k e c

t D i i lift：Design service lifek：Characteristic value of carbonation ratee：Coefficient representing the extent of environmental action

）c：Material factor for concrete (= 1.0）

k = p pk p pp = -3.57 + 9.0 W/Cp：Safety factor for p

10

Durability design for chloride‐induced deterioration

Mechanism of penetration and transportation of chloride ion  in concrete are very complex. 

Ex Modeling of Cl‐ penetration

,...,1,...,12

2

2

2

, baaww

aaww

aa

eaa ccf

x

D

xc

x

c

x

Dc

cD

t

c

Ex. Modeling of Cl penetration

, ,, ,22

ww xxxxxxt

Diffusion due to t ti di t

Water transportGeneration and disappearance  by chemical reaction

concentration gradient

Electro‐migration of ions due to electrical potential gradient

Condensation due to water dissipation

Penetration of chloride ion into concrete is usually expressed as a simple diffusion equation. p q

2

2CD

t

Ca

(Fick’s second law of diffusion）2xt a (Fick s second law of diffusion）

11

Prediction of corrosion initiation time

Chloride ion accumulates on the surface of steel bar over a certain amount => Threshold value

CoverFactors governing the corrosion

Cl‐Steel bar

Environment1) Supply of chloride ion

‐> C0: Surface chloride ion concentration(depending on the environment) l(depending on the environment)

2) Diffusivity of chloride ion in concrete> D : Apparent diffusion coefficient

Cl‐

‐> Dap: Apparent diffusion coefficient(depending on concrete quality)

3) Distance from the surface to rebar3) Distance from the surface to rebar‐> Cover depth

F 1) 3) b b i d/ ifi d b d il d i i

Dr Boonchai, Dr Wang will be contributing.

12

Factors 1)‐3) can be obtained/quantified by detailed inspection

When is the passive‐film destroyed?

Lambert et al.

Lukas

Thomas et al

Tuutti

Locke & Siman

B f th t l

Hansson & Sorensen

Schiessl & Raupach

Thomas et al.

Elsener & Bohni

Henriksen

Bamforth et al.

Structure

Stratfull et al.

Vassie

West & HimeStructure

Out‐room test

In‐room test

0.0 0.5 1.0 1.5 2.0 2.5

Total chloride ion concentration (% wt. cement)

13

Prediction of deterioration

(1) Assumed rule and process

ance

Initial (2) Present status

erform

(2) Present status

(3) Prediction

ctural p Present

Modification of

Struc

rule and processScenario correction

TimeAssessement

14

An example of chloride ion profiles

S‐s S‐m S‐lSeaward Landward

12kg/m

3)

B‐s B‐m B‐lHWL

8

10

12

ntration(k B‐s

B‐mB‐lS‐sS‐m

4

6

onconcen S‐m

S‐l

0

2

0 20 40 60 80 100

Chlorideio

Depth from the surface (mm)C

Height from HWL and wave conditions washing the surface have some effects

15

Surface chloride ion concentration, C0

Stain Spalling DelaminationCrack

10.7

15.116.915.7 12.713.5

16.9 11.8

10.59.2 10.5

9.9 10.8 10.7

15.3 15.5 11.0

15 9 16 8

16.5 15.3

12.711.4 7.1 10.6

8.07.8

8.0

11.0

15.1

12.811.5

15.9 16.8

15.3

13.1 16.9 11.5

14.5 8.6

12.3 6.315.4

11.512.8

13.5

10.6

(unit: kg/m3)

More than twice between the adjacent pointsMore than twice between the adjacent points

16

Mass‐loss of steel barL it di l t l b

20

25

20-2515-20

20

2520-2515-2010-15

Longitudinal steel barMass‐loss (%)

Ave: 1.3%Std: 4.3%

)

質量減少率 (%)

Ave: 1.8%Std:  3.5%%

)

Longitudinal steel barMass‐loss (%)

5

10

1510-155-100-5

5

10

1510 155-100-5

Mass‐loss (%

Mass‐loss (%

50

35

0

65

0

95

0

12

50

15

50

18

50

323005397000

50

35

0

65

0

95

0

12

50

15

50

18

50

433205407810

Transverse steel bar Transverse steel bar

20

25

20

25

Ave: 0.8%Std: 2.5%

Ave: 1.0%Std:  2.1%

5

10

15

10

15

20

Mass‐loss (%)

Mass‐loss (%)

726

74

1

10

48

13

52

16

70

19

54

50

350

650

950

0

5

14835

2

16

70

19

54

350

6500

5

M

12

74271

12

742

674

1

10

41 50(unit: mm)

Mass‐loss  Average cross‐sectional area loss 17

Envelope curves of load vs deflection

125

75

125

25

 (kN

)

‐25Load

No‐corrosion

l h

‐125

‐75 Slight corrosion

Heavy corrosion

125

‐50 ‐25 0 25 50

Midspan deflection (mm)

18

Corrosion of steel bar in concrete

cross‐sectional loss

rustrust

Grade‐c slab From Grade‐a slab

19

Influence on localized corrosion 

Yield load Ultimate loadYield load

0 8

1.0

0.8

1.0

tio

Ultimate load

0.6

0.8

oad

 ratio

0 4

0.6

0.8

te load

 rat

Wide spread corrosionWide spread corrosion

0.2

0.4

Yield l

0.2

0.4

Ultim

atWide spread corrosion

Localized corrosion Localized corrosion

0.00 10 20 30 40 50 60 70

Average cross‐sectional area loss (%)

0.00 10 20 30 40 50 60 70

g ( )

20

Structural capacity vs deterioration grade

1.5 

1.0 m load

Cal)

0.5 

Maxim

um

(Exp/C

0 0

M

Exp.Ave.

0.0 d c         b     a

Deterioration grade

Grade Data Average SD -1 +1

d 2 1.07 0.03 1.04 1.10

c 10 1.06 0.25 0.81 1.31

b 8 1.04 0.25 0.79 1.29

a 8 0.76 0.24 0.51 1.00 21

Prediction by stochastic mathematical model

Physical deterioration models (Fick’s diffusion model, etc ) are based on relevant theories and may beetc.) are based on relevant theories and may be applicable for the service life design, but, in practice,1) Threshold value is not clear,1) Threshold value is not clear,2) Frequent coring is not preferable, and3) Very wide variations appear.

Consequently, other approaches are widely undertaken: Stochastic mathematical modelStochastic mathematical model1) Survival analysis when damage data are not available

ex. R(t)=(a+1)/(a+e (t-c) )

2) Markov model when damage data are available

22

Markov model

The Markov model allows analysts to study events y ythat recur over time.

The Markov property states that the probability distribution for the system at the next step (and in fact at all future steps) only depends on the current t t f th t d t dditi ll thstate of the system, and not additionally on the state of the system at previous steps.

The changes of state of the system are calledThe changes of state of the system are called transitions, and the probabilities associated with various state‐changes are called transition gprobabilities.

23

Tendencies of analysis

Probability px: 0.10 Year t: 10

Percentage t = 2

t = 20

ercentage

px = 0.01

px = 0.10px = 0.20

Grade of deterioration Grade of deterioration

P t = 40t = 60

Pe px = 0.30

47 years10 years 31 years

Actually inspected results

47 years

40

60

80

100

entage, %

10 years 3 yea s

0

20

40

0 I II III IV V

Perce

0 I II III IV V 0 I II III IV V

Grade of deterioration

0 I II III IV V 0 I II III IV V

24

Transition probability, px

0.25

0.20

0.25RC beamRC slab

bility p

x The linear relationship is found between the probability and the rate of deterioration grade

0 10

0.15

on probab

the rate of deterioration grade.

0.05

0.10

Transitio

The probability can represent the deterioration rate.

0.000.00 0.05 0.10 0.15 0.20 0.25

d f d /Average grades of deterioration / year=The rate of deterioration

25

LCC for scenario evaluation

108 Yen

LCC

InterventionI i i lInitial

P C P C P CBeam

P C P C P C P

Slab Preventive Corrective Improved preventive

Replacement

26

NPV for scenario evaluation

108 YenLCC

BeamP C P C P C PBeam

Slab Preventive Corrective Improved preventive Replacementp

27

Role of participating member (As of Mar. 2010) 

Study item Study sub item Investigator

Damage Chloride ion ingress Jin, Takewakaassessment Frost damage Taguchi, Hama

Deterioration mechanism

Chloride ion ingress Ann, Boonchai, Jin, SugiyamaWang Takewaka (simulation)mechanism

and damage prediction

Wang, Takewaka (simulation)

Corrosion rate Boonchai (Withit), Takewaka

Frost damage Hama, Uedag

Combined actions Wittmann, Katsura, Sato

Service life prediction

Task Force to be set upprediction

Interventions Rehabilitation Ahmed, Zhang, Sato

Preventive measures Takewaka, Wittmann, Ann, ,

Guideline/Code

Durability design Performance assessment

Sugiyama, Wittmann

LCM Y k tLCM Yokota

28

Contributions for standardizationConcept and framework of LCM

Performance: HU (Yokota)Environmental: HU (Sugiyama)

Scenario by durability designChloride‐induced deterioration: CU, DLUT, KU, ZJU, YUF t d MIT PWRIFrost damage: MIT, PWRICombined deterioration: QTU, HRO Intervention plan: HU (Sato)Carbonation (just refer)Carbonation (just refer)

Performance assessmentStructural capacity verification: HU (Sato), PARIChloride‐induced deterioration and corrosion: CU DLUT KU YU ZJUChloride induced deterioration and corrosion: CU, DLUT, KU, YU, ZJUFrost damage: MIT, HRO Combined:

Scenario for performance recoverySelection of rehabilitation: ASU, HU(Sugiyama, Sato), YUPerformance (mechanical and durability) recovery quantification: HU (Sato, 

29

( y) y q ( ,Sugiyama)Progress of deterioration after intervention: same as above

Thank you for your attention

30