Life-cycle Performance, Reliability, Risk, Resilience and ... · Lehigh University, Bethlehem, PA,...

Dan M. Frangopol Department of Civil and Environmental Engineering,

ATLSS Engineering Research Center, Lehigh University, Bethlehem, PA, USA

Life-cycle Performance, Reliability, Risk, Resilience and Sustainability of Civil

Infrastructure November 1, 2013

2 Introduction

• The United States has four million (4,067,076) miles of public roads (as of 2010)*.

• The road network carries 86% of passenger transportation and

60% of freight transportation. • The road network contains more than 600,000 bridges (604,460) *.

RC 41.5%

Steel 30.4%

PC 23.6%

→ % of bridge types by number → % of bridge types by deck area

RC 19.2%

Steel 43.6%

PC 35.7%

* FHWA, (2011). “National bridge inventory.” United States Department of Transportation, Federal Highway Administration.

Other 4.5% Other 1.5%

3 Introduction

• Approximately 42% of the bridges in the United States are more than 50 years old*.

• 24.2% of bridge inventory are either structurally deficient or

functionally obsolete*.

TIME (years)

0

10.000

20.000

30.000

40.000

50.000

60.000

NU

MB

ER O

F B

RID

GES

, × 1

04 6

5

2

4

3

1

0 0,00E+00

1,00E+05

2,00E+05

3,00E+05

4,00E+05

5,00E+05

6,00E+05

7,00E+05FUNCTIONALLY OBSOLETE STRUCTURALLY DEFICIENT PROPERLY FUNCTIONAL

TIME (years)

6

5

2

7

4

3

1

0 NU

MB

ER O

F B

RID

GES

, × 1

05

FHWA, (2011). “National bridge inventory.” United States Department of Transportation, Federal Highway Administration.

4

• The number of structurally deficient and functionally obsolete is in continuous decrease since 1990.

• Improving the bridge inventory condition requires an average

annual investment of $17 billion*.

• In 2004, a total of $10.4 billion was spent on bridge rehabilitation*.

Introduction

24

25

26

27

28

29

30

31

32

1996 1998 2000 2002 2004 2006 2008 2010

TIME (years)

PER

CEN

TAG

E O

F D

EFIC

IEN

T B

RID

GES

, %

* ASCE, (2009). “Report Card for America’s Infrastructure.” American Society of Civil Engineers.

Introduction

• This deficiency in funding requires innovative structural management techniques to plan for future inspections and repair actions and cost effective maintenance strategies.

• Bridges are mandated to be inspected at least every two years; however, these visual inspections may not ensure that fatal problems will be detected.

CONCRETE SLAB CRACKS

FATIGUE CRACKS

www.wikipedia.com www.wikipedia.com

6

Aggressive environmental

conditions: • Corrosion

Structures deteriorate

progressively in time

Extreme events: • Floods • Hurricanes • Earthquakes • Blasts • Fires

Collapse if cannot withstand

adequate amount of local damage

Reduced safety or

collapse if no maintenance

Sudden damage

Different ways of damage occurrence

7

How safety, redundancy and durability affect the life-cycle design, assessment, maintenance and management of civil infrastructure systems?

Motivation

Sources: Meteorological Satellite Program, Associated Press, CCTV News, and Minnesota State Department of Transportation

Northeast Blackout 2003

Laval Overpass Collapse 2006

Hurricane Katrina 2005

I35W Minneapolis Bridge 2007

How robust and resilient engineered systems be?

What is the appropriate level of safety for design?

How do we best inspect, maintain, repair, and manage aging infrastructure?

8

An example to provide an estimate of risk as applied to highway bridges.

Site Recovery Costs $400 million

Winning bid for new structure $234 millionState liability cap of $1 million on 13 deaths $13 millionEstimated $10,000 hospital bill on 100 injured $ 1 millionLawsuits, legislation, loss of productivity, and investigation (not estimated)

Total Estimated Consequence of Failure US$893 million

Estimated user costs: 140,000 vehicles/day, 10 mile detour, IRS allocated .48 cent/mile, and 365 day construction time of new bridge

Table 1. Estimated costs associated with the collapse of the I35W bridge in Minneapolis, Minnesota, USA, 2007 [11, 12]

$245 Million

Risk (consequence of failure)

9

2013 Report Card for America’s Infrastructure

( Gives Nation a D+, Estimates Cost at $3.6 Trillion )

10

Grades for Insfrastructure Categories According to 2013 Report Card for America’s

Infrastructure

11 ESTIMATED 5-YEAR INVESTMENT NEEDS IN BILLIONS OF DOLLARS

(taken from Failure to Act Report, ASCE, 2013)

Cumulative Infrastructure Needs by System Based on Current Trends Extended to 2020 and 2040 (Dollars in $2010 billions)

12

BACKGROUND

Performance indicators for civil infrastructure

r or s

PDF

0

Sf ( s )Rf ( r )

( ) ( )0

F R Sp F s f s ds∞

= ∫

( )0 0

s

F R ,Sp f r ,s dr ds∞ = ∫ ∫

( )0

F Mp f m dm−∞

= ∫

0

Area = Probability of failure

Mf ( m )M Mµ βσ=

Mµ m

Reliability

Probability of failure M R S= −Safety Margin

Probability of failure

( )tβ Time dependence

Ang and Tang (1984); Leemis (1995)

R and S are statistically independent

General case

M

M

µβσ

=Reliability Index

2 2

R S

R S

µ µβσ σ−

=+ ( ) ( )1 1 1S Fp pβ − −= Φ = Φ −

13

BACKGROUND Performance indicators for civil infrastructure

Risk ( )R t Time dependence

Risk is quantified by combining the probability of occurrence and the consequences of events generated by hazards

Ang and De Leon (2005); CIB (2001); Ellingwood (2001); Decò and Frangopol (2011)

1 2 X 1 2 1 2( , , , ) ( , , , )m m mR x x x f x x x dx dx dxκ= ⋅ ⋅ ⋅∫ ∫ ∫ Instantaneous total risk R

,1

[ | ] [ ]n

m i i ii

R C P F H P H=

= ⋅ ⋅∑

Zhu et al. (2013)

Consequences of hazard(s)

Joint PDF describing occurrence probability

of hazards

Cm,i : monetary value associated with the consequences of failure P[Hi] : probability of occurrence of an event resulting from a hazard P[F | Hi] : conditional failure probability given the occurrence of a hazard n : total number of hazards considered within the analysis

R p χ= ⋅

Simplest formulation

Sustainability

• Societal • Environmental • Economic

14

BACKGROUND Hazard Analysis Hazards are actions that pose potential harm to a structure or the persons occupying a structure

1) Man made hazards

• Explosions • Accidents • Terrorism

2) Natural hazards

• Earthquakes • Floods • Wind • Fires

Perf

orm

ance

TH

Time

Deterioration

Sudden hazard

15

BACKGROUND Consequence evaluation Necessary step of risk assessment

•The consequences of component and system failure depend on the type, size, and importance of the structure

•Each consequence is quantified in terms of monetary values •The consequences are categorized as direct and indirect costs

( )Direct g g gC t c G L= ⋅ ⋅The direct cost of a bridge girder failure

( )Reb RebC t c W L= ⋅ ⋅The indirect cost of rebuilding a bridge

structure

Saydam et al. (2013b)

( ) (1 )tFV t PV r= ⋅ +

Replacement cost of a bridge girder Example: bridge

• Running cost of the detoured vehicles, • Time loss due to the unavailability of the

highway segment

Future value of an expenditure

Flow chart for risk-based optimization

Generate initial population

Stopping criteria?

Decision making for preferred solution

Genetic algorithms

Generate new population

No

Yes

Current Pareto optimal solutions

Evaluate condition, performance, and cost

For each solution

Calculate fitness of objectives

START

END

16

BACKGROUND Integrated probabilistic life-cycle management framework Effects of maintenance

Optimization Pe

rfor

man

ce

Time

Performance threshold

EM PM

Preventative maintenance (PM) Essential maintenance (EM)

Genetic algorithms are used •Robust against convergence to local minima •Ease of implementation (MATLAB) •Multiple objectives and complex constraints

Liu and Frangopol (2005)

17

BACKGROUND Life-cycle management, optimization, and decision making Life-cycle performance assessment and intervention scheduling •Predict a structure’s performance throughout its lifetime •Determine possible intervention strategies and associated costs •Perform optimization to determine optimal intervention planning scheduling (inspection, maintenance, monitoring, removal, and renewal actions)

Life-cycle cost

Perf

orm

ance

Design variables: • t1 , t2 ,…, tn (time

intervention actions are performed)

• IA1 , IA2 ,…, IAn (respective intervention actions)

Life-cycle cost

Perf

orm

ance

Pareto optimal set

18

CONTENTS

INTRODUCTION SYSTEM PERFORMANCE ASSESSMENT AND PREDICTION

INTEGRATION OF SHM IN LCM ROLE OF OPTIMIZATION CONCLUSIONS

19

LEVELS OF PERFORMANCE QUANTIFICATION

Com

plex

ity o

f the

Ana

lysi

s

20 20 PERFORMANCE PROFILE WITH CORROSION AND SEISMIC ACTION

PERFORMANCE PROFILE

REPAIR COST

TIME

PE

RFO

RM

AN

CE

IND

EX

CO

ST

TIME

EARTHQUAKE

EARTHQUAKE EARTHQUAKE

RETROFIT REPAIR (2) REPAIR (1)

RETROFIT

REPAIR (1)

REPAIR (2)

PERFORMANCE THRESHOLD

CORROSION INITIATION

21

INTRODUCTION

LIFE-CYCLE INTEGRATED MANAGEMENT FRAMEWORK

Structural Performance Assessment & Prediction

Information from Structural Health Monitoring & Uncertainty Analysis

Improved Structural Performance

Assessment & Prediction

Optimum Maintenance-Monitoring-Management

Strategies TOOLS

Optimal Decision

Existing and New Civil Infrastructure Systems :

Bridges, Buildings, Networks,…

APPLICATIONS

22

CONTENTS

INTRODUCTION SYSTEM PERFORMANCE ASSESSMENT AND PREDICTION

INTEGRATION OF SHM IN LCM ROLE OF OPTIMIZATION CONCLUSIONS

23

SYSTEM PERFORMANCE ASSESSMENT AND PREDICTION

Commonly employed methodology to design based on component analysis:

• Considerable waste of resources due to over-conservatism for redundant

systems • Overestimation of the actual load carrying capacity for weakest-link

systems

System Reliability

24

Performance indicators System reliability

• Load and resistance modeling • Limit state equations for components • System analysis

( ) ( ) ( )i i ig t R t S t= −

Series system 3 2 1 ( ){ }( )1

0N

F ii

p p g=

= ≤ X

Parallel system

1

2

3

( ){ }( )1

0N

F ii

p p g=

= ≤ X

Series-parallel system

2

3 1 ( ){ }( )

1 10

M K

F i ,kk i

p p g= =

= ≤ X

25

SYSTEM PERFORMANCE ASSESSMENT AND PREDICTION

System Redundancy and Robustness • System redundancy → the ability of a structural system to redistribute the applied load after reaching

the ultimate capacity of its main load-carrying members

• Robustness → the ability of a structural system to resist extreme actions without suffering

from damages disproportionate with respect to the causes that have generated them

26

SYSTEM PERFORMANCE ASSESSMENT AND PREDICTION

System Redundancy and Robustness • Time-variant redundancy indices (Okasha and Frangopol, Structural Safety, 2009)

( ) ( )( )

( ) ( )1

( )

( ) y sys f sys

f sys

P t P tRI t

P t−

=

( ) ( ) ( ) ( )2 ( ) f sys y sysRI t t t= −β β

( ) ( )( )3 ( ) wc s

s

An t An tRI t

An t−

=

Py(sys)(t) = probability of first member failure occurrence at time t

Pf(sys)(t) = probability of system failure occurrence at time t

βy(sys)(t) = reliability index wirth respect to first member failure occurrence at time t

βf(sys)(t) = reliability index with respect to system failure at time t

Ans(t) = unavailability of the system at time t

Anwc(t) = unavailability of the weakest component at time t

27

Structural Analysis

Interface Algorithms

Optimization

Reliability Analysis

Life-Cycle Performance Assessment, Prediction, Optimization, and Decision

Making

Design Variables

Objectives and Constraints

Limit State Equations

Structural Response

Structural Properties

Performance Indicator

Risk Analysis

Expected Losses

Probability of Failure

Hazard Identification

Consequence Evaluation

Risk Attitudes Computational framework for the life-cycle management of structures

Risk Analysis

Optimization

Interface Algorithms

Life-Cycle Performance Assessment, Prediction, Optimization, and Decision

Making

28

χ⋅= fPRPf probability of failure

χ consequences caused by failure in terms of monetary loss

Structural Vulnerability Consequences

Quantitative Risk Analysis

Hazard Identification

Aleatory and Epistemic Uncertainties

Decò, A. and Frangopol, D. M. (2011). “Risk Assessment of Highway Bridges under Multiple Hazards,” Journal of Risk Research, Taylor & Francis, 14(9), 1057–1089.

Risk Definition (Ang and De Leon 2005)

29

Performance indicators

Risk Hazard Analysis

• Natural hazards • Man-made

hazards Probability of

occurrence

Vulnerability Analysis

Reliability Analysis System probability

of failure given hazard occurrence

P(F | H)

Consequence Evaluation

• Commercial losses • Safety loss • Impact to society • Environmental impact

Monetary cost associated with

structural failure Cf

Risk Assessment

Risk = P(H) · P(F | H) · Cf

P(H)

Sustainability

30

Natural

Man

Made

Earthquakes

Hurricanes

Floods

Corrosion

Overloading

Explosions

Fire

Accidents

Hazards Identification

I-39 Northbound Bridge over the Wisconsin River

32

Time-dependent Vulnerability

CDFs of the Time-to-Failure

Time-to-Failure (years)

(d)

0 20 40 60 80 100 120 140 160 180 200

Bridge lifetime (80 years)

Scour κ = 1.54 λ = 0.014

Live loads κ = 5.57 λ = 0.0097

Earthquakes κ = 2.15

λ = 4.53x10-6

PDF

of T

ime-

to-F

ailu

re

(a)

0 10 20 30 40 50 60 70 80

Time (years)

Prob

abili

ty o

f Fai

lure

TDPf,sys

Live loads

Pf,sys

(b)

0 10 20 30 40 50 60 70 80

Time (years)

Prob

abili

ty o

f Fai

lure

TDPf,SC

Pf,SC

Scour

Earthquake

(c)

0 10 20 30 40 50 60 70 80

Time (years)

Prob

abili

ty o

f Fai

lure

PCD TDPCD

10 -6

10 -5

10 -4

10 -3

10 -2

10 -1

10 0

10 -3

10 -2

10 -1

10 0

10 -10

10 -9

10 -8

10 -7

0.000

0.005

0.010

0.015

0.020

0.025

PDFs of the Time-to-Failure

33

0 10 20 30 40 50 60 70 80

Time (years)

Tim

e-D

epen

dent

Tot

al

Ris

k (U

SD m

illio

ns) µ(R) + σ(R)

µ(R) - σ(R)

µ(R)

(a)

(b)

0 10 20 30 40 50 60 70 80

Time (years)

Nor

mal

ized

Indi

rect

Ris

k

0.0

0.2

0.4

0.6

0.8

1.0

1.2

µ(NRID) - σ(NRID)

µ(NRID) + σ(NRID) µ(NRID)

0

2

4

6

8

10

12

14

16

18 Profiles of the Time-

Dependent Total Risk

Standard deviation of the time-dependent total risk grows over time

Profiles of the Time-Dependent

Normalized Indirect Risk Index

( ) ( )( ) ( )tRtR

tRtNRIDD

IDID +

=

34

CONTENTS

INTRODUCTION SYSTEM PERFORMANCE ASSESSMENT AND PREDICTION

INTEGRATION OF SHM IN LCM ROLE OF OPTIMIZATION CONCLUSIONS

35

PERFORMANCE INDEX PROFILE WITH AND WITHOUT MONITROING

TIME

PE

RFO

RM

AN

CE

IND

EX

WITHOUT MONITORING

WIHTOUT MONITORING

PERFORMANCE THRESHOLD

SERVICE LIFE WITH MONITORING

SERVICE LIFE WITHOUT MONITORING

UPDATING BASED ON MONITORING

Inaccurate prediction → Tremendous consequences

due to failure occurrence (later reaching of the threshold is

predicted)

INTEGRATION OF SHM IN LCM

36

PERFORMANCE INDEX PROFILE WITH AND WITHOUT MONITROING

TIME

PE

RFO

RM

AN

CE

IND

EX

PERFORMANCE THRESHOLD

SERVICE LIFE WITHOUT MONITORING

SERVICE LIFE WITH MONITORING

UPDATING BASED ON MONITORING

WIHTOUT MONITORING

Inaccurate prediction → Unnecessary

Maintenance Action (earlier reaching of the threshold is

predicted)

WITHOUT MONITORING

INTEGRATION OF SHM IN LCM

37

Combining SHM & LCM

Structural Health Monitoring

Actual Structural Data

Predictive in nature? Actionable Information?

Life-Cycle Management

Predictive Management Tool

Accuracy of random variables? Limited use of structure-specific

structural data

Combined Approach

Predictive Tool

Actual Structural Data

Actionable Information for the bridge manager

Combining SHM and LCM has the benefit that each method’s advantages complement the other’s disadvantages

Frangopol and Messervey "Maintenance Principles for Civil Structures,“ Chapter 89 in Encyclopedia of Structural Health Monitoring, John Willey & Sons, 2009

38

SHM design considerations: Bridge Importance

isys

netiRIF

,ββ

∂∂

=

A bridge manager will likely desire to focus effort on the most critical bridge, or bridges in a network. Such an analysis requires the consideration of connectivity, user satisfaction, and network reliability.

The reliability importance factor (RIF) is defined as the sensitivity of the bridge network reliability with respect to a change in an individual bridge’s reliability

39 MONITORING WITHIN A LIFE-CYCLE CONTEXT

THE MOST WIDELY USED DESIGN CRITERION → MINIMUM EXPECTED LIFE-CYCLE COST

ET T PM INS REP FC C C C C C= + + + +

CET= expected total cost, CT= initial cost,

CPM= expected cost of maintenance, CINS= expected cost of inspection,

CREP= expected cost of repair, and CF= expected cost of failure

Inclusion of monitoring cost

0 0 0 0 0 0ET T PM INS REP F MONC C C C C C C= + + + + +

General form of the expected LCC

40 MONITORING WITHIN A LIFE-CYCLE CONTEXT

COST OF MONITORING CMON

MON T OP INS REPC M M M M= + + +

MT= expected initial design/construction cost of the monitoring system,

MOP= expected operational cost of the monitoring system,

MINS= expected cost of inspection of the monitoring system,

MREP= expected cost of repair cost of the monitoring system

BENEFIT OF THE MONITORING SYSTEM, BMON

0MON ET ETB C C= −

Timely maintenance intervention,

Reduction of failure cost

41

Optimum Solution based on LCC Minimization without Monitoring

TOTAL LIFE-CYCLE COST

OPTIMUM SOLUTION A

INITIAL COST

FAILURE COST

COSTA

PERFORMANCE INDEX

PR

ES

EN

T VA

LUE

OF

EX

PE

CTE

D C

OS

TS

MAINTENANCE COST

NEAR-OPTIMAL REGION

MONITORING WITHIN A LIFE-CYCLE CONTEXT

42

OPTIMUM SOLUTION B

TOTAL LIFE-CYCLE COST

INITIAL COST

FAILURE COST

COSTB

PR

ES

EN

T VA

LUE

OF

EX

PE

CTE

D C

OS

TS

PERFORMANCE INDEX

NEAR-OPTIMAL REGION

MAINTENANCE COST & MONITORING COST

Optimum Solution based on LCC Minimization with Cost-Effective Monitoring

MONITORING WITHIN A LIFE-CYCLE CONTEXT

0 0MON ET ETB C C= − >

43

OPTIMUM SOLUTION C

TOTAL LIFE-CYCLE COST

FAILURE COST

INITIAL COST

PR

ES

EN

T VA

LUE

OF

EX

PE

CTE

D C

OS

TS

COSTC

PERFORMANCE INDEX

NEAR-OPTIMAL REGION

MAINTENANCE COST & MONITORING COST

Optimum Solution based on LCC Minimization without Cost-Effective Monitoring 0 0MON ET ETB C C= − <

MONITORING WITHIN A LIFE-CYCLE CONTEXT

44

CONTENTS

INTRODUCTION SYSTEM PERFORMANCE ASSESSMENT AND PREDICTION

INTEGRATION OF SHM IN LCM ROLE OF OPTIMIZATION CONCLUSIONS

45

ROLE OF OPTIMIZATION

• Under uncertainty, decision related to the civil infrastructure management should be made by

maximizing the structural performance & minimizing the life-cycle cost

Design and Maintenance planning can be best formulated as a multi-objective optimization problem

PERFORMANCE INDEX

LIFE

-CYC

LE C

OS

T

GROUP OF OPTIMIZED TRADE-OFF SOLUTIONSWITHOUT MONITORING

TRADE-OFF SOLUTIONS BETWEEN TWO CONFLICTING OBJECTIVES

46

ROLE OF OPTIMIZATION

PERFORMANCE INDEX

LIFE

-CYC

LE C

OS

T

GROUP OF OPTIMIZED TRADE-OFF SOLUTIONS WITHOUT MONITORING

GROUP OF OPTIMIZED TRADE-OFF SOLUTIONS WITH MONITORING

OPTIMAL PARETO FRONT

TRADE-OFF SOLUTIONS BETWEEN TWO CONFLICTING OBJECTIVES

A

B

C

A to B: Cost-Effective SHM B to C: Not Cost-Effective SHM

47

Risk-based Optimum Maintenance

Reducing the failure probabilities of the structure under hazards

Reducing the consequences caused by structure failure

Risk mitigation strategies:

Two types:

Essential maintenance

Kong et al. (2000)

Preventive maintenance

Zhu, B. and Frangopol, D. M. (2011). “Risk-Based Approach for Optimum Maintenance of Bridges under Traffic and Earthquake Loads”, Journal of Structural Engineering, ASCE, 139(3), 422–434.

48

Application: E-17-AH Highway Bridge

49

Case Study: E-17-AH Bridge

Essentials maintenance:

Risk threshold: 5.0×105 Optimum: the lowest cost per year increase of service life

Estes (1997)

t=47 years t=88 years

Replacing deck

50

Case Study: E-17-AH Bridge

Preventive maintenance:

Risk threshold: 5.0×105

Optimum: the lowest cost per year increase of service life

51

Case Study: E-17-AH Bridge

Preventive maintenance:

Number of PM =5

Resilience as Optimization Criterion for the Rehabilitation of Bridges Belonging to a

Transportation Network Subject to Earthquake

Advanced Technology for Large Structural Systems (ATLSS) Engineering Research Center Department of Civil and Environmental Engineering

Lehigh University

Dan M. Frangopol Dist.M.ASCE and Paolo Bocchini M.ASCE

53

DESCRIPTIVE DEFINITIONS OF RESILIENCE

Economic

Social

Organizational

Technical

Resourcefullness

Redundancy

Rapidity

Robustness

Faster recovery

More reliability

Lower consequences

RESILIENCE

4 dimensions of resilience

4 properties of resilience

3 results of resilience

[Bruneau et al. 2003]

54

PROPOSED APPROACH • Robustness

• Rapidity

• Redundancy

• ...

• ...

• Social impact

• Economic impact

• ...

• Reliability

• Risk

• ...

• ...

RESILIENCE

Multi-criteria Pareto

Efficiency

55

MULTI-CRITERIA APPROACH

POSSIBLE OBJECTIVES • Maximize resilience index 𝑅𝑅4

• Minimize the total cost of interventions (associated with resourcefullness)

• Minimimize the total recovery time (rapidity)

• Minimize the time required to reach a target functionality level (advanced use of rapidity)

• Minimize the impact of an extreme event (robustness)

POSSIBLE CONSTRAINTS • Total cost has to be lower

than the available budget.

• Deliver minimum functionality levels at certain instants (minimum acceptable recovery path)

• Maximum number of simultaneous interventions (associated with resourcefullness)

• additional constraints on the rehabilitation parameters

56

PARETO FRONT

Resilience index

Tota

l re

stor

atio

n c

ost

Maximum cost

Pareto front

Optimal and feasible

strategies

non-feasible strategies

Region of feasible, but non-optimal strategies

No strategies in this region

Region of non-feasible strategies

Optimal but

57

APPLICATION TO BRIDGE NETWORKS

System: bridge network

Functionality 𝑄𝑄(𝑡𝑡): ability to effectively redistribute traffic flows

Data: damage level of all the bridges after an earthquake

Rehabilitation strategies: defined by the schedule of the interventions and the recovery speed (budget)

Objectives: maximize resilience index, minimize cost of interventions

Constraints: maximum budget, maximum simultaneous interventions, limited ranges for design variables

58

RECOVERY PROCESS OF A BRIDGE

no

Damage level

Time, 𝑡𝑡

Intervention in progress

minor moderate

major collapse

Functionality carried traffic

Functionality crossed traffic

100%

0%

50%

100%

0%

50%

Intervention in progress

extreme event

2 lanes closed out of 4

2 lanes closed out of 4

Out of service

59

ILLUSTRATIVE EXAMPLE

0%

25%

50%

75%

100%

Time,

Func

tiona

lity,

𝑄𝑄(𝑡𝑡

)

𝑡𝑡 𝑡𝑡0 𝑡𝑡0 + 𝑡𝑡ℎ 𝑡𝑡1𝑇𝑇 𝑡𝑡2𝑇𝑇

𝑄𝑄1𝑇𝑇

𝑄𝑄2𝑇𝑇 𝑄𝑄1

Strategy A

Strategy B

Strategy C

Minimum acceptable

path

60

ILLUSTRATIVE EXAMPLE

0 50% 0

Resilience, 𝑅𝑅

Tota

l Reh

abilit

atio

n C

ost,

𝐶𝐶

𝐶𝐶𝑚𝑚𝑚𝑚𝑚𝑚

Pareto Front

100%

Strategy A

Strategy B

Strategy C

61

COMPUTATIONAL PROCEDURE

Network level

Functionality over time

Individual bridge level

Serviceability over time

Interface Traffic assignement

and distribution

MULTI-OBJECTIVE OPTIMIZATION

62 DESIGN VARIABLES: (i) time between occurrence of an extreme event and the beginning of the rehabiliattion activities, and (ii) damage recovery rate

63

CONSTRAINTS ON DESIGN VARIABLES

t0 t0+δb t0+δb+lb0/tan(θb) t0+th 0

1

2

3 lb0 4

Time t

Dam

age

leve

l l

b Idle time δ b Works in progress

Damage recovery rate θ b

COMPONENT b

θb cannot be higher than an upper limit (maximum recovery speed 80°). Moreover θb is never convenient below a lower limit (30°).

δb has to be included in [0, th] = [0, 2 years]

Maximum number of simultaneous interventions: 6

64

ANALYTICAL FORMULATION

Given: (input)

network topology; traffic data; road capacities; secondary detour routes characteristics; bridge locations; approximate rehabilitation costs; discount rate of money; 𝑙𝑙𝑏𝑏0 (post-event damage level for bridge 𝑏𝑏) ∀ 𝑏𝑏 = 1,2, … ,𝑁𝑁𝐵𝐵 ;

find: (design variables)

𝛿𝛿𝑏𝑏 (idle time for bridge 𝑏𝑏) ∀ 𝑏𝑏 = 1, 2, … ,𝑁𝑁; 𝜃𝜃𝑏𝑏 (damage recovery rate for bridge 𝑏𝑏) ∀ 𝑏𝑏 = 1, 2, … ,𝑁𝑁𝐵𝐵;

so that: (objectives)

𝑅𝑅 = 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 ; 𝐶𝐶 = 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 ;

subject to: (constraints)

0 ≤ 𝛿𝛿𝑏𝑏 ≤ 𝑡𝑡ℎ , ∀ 𝑏𝑏 = 1, 2, … ,𝑁𝑁𝑏𝑏 ; 𝜃𝜃𝑚𝑚𝑚𝑚𝑚𝑚 ≤ 𝜃𝜃𝑏𝑏 ≤ 𝜃𝜃𝑚𝑚𝑚𝑚𝑚𝑚 , ∀ 𝑏𝑏 = 1, 2, … ,𝑁𝑁𝑏𝑏 ; 𝐶𝐶 ≤ 𝐶𝐶𝑚𝑚𝑚𝑚𝑚𝑚 ; 𝑁𝑁𝑆𝑆𝑆𝑆 𝑡𝑡 ≤ 𝑁𝑁𝑆𝑆𝑆𝑆𝑚𝑚𝑚𝑚𝑚𝑚 , ∀𝑡𝑡 ∈ [𝑡𝑡0, 𝑡𝑡0 + 𝑡𝑡ℎ] .

65

NUMERICAL EXAMPLE (Bocchini and Frangopol, Prob. Eng. Mech. 2011)

66

REPRESENTATIVE SOLUTION S2

67

LATEST APPLICATION: SANTA BARBARA

68

LATEST APPLICATION: SANTA BARBARA

7880

8284

8688

66.5

77.5

840

41

42

43

44

45

46

Time to 80% functionality

[months]

Total cost of interventions

[$ million]

Resilience index [%]

San Francisco

Richmond San Rafael

San Jose

Santa Clara

Oakland

Hayward

Fremont

San Mateo

San Francisco

Bay

Berkeley

Redwood City

Pacific Ocean

Highway Network of Upper Bay

Area

Highway Network of Lower Bay

Area

Highway Segment Link between Networks

5 mi

10 km

FUTURE TARGET: SF BAY AREA

Credits: Duygu

Saydam

69

San Francisco

Richmond San Rafael

San Jose

Santa Clara

Oakland

Hayward

Fremont San Mateo

San Francisco Bay

Berkeley

Redwood City

Pacific Ocean

Highway Segment

Link b etween Networks

5 mi

10 km

Highway Network of U pper Bay Area

Highway Network of Lower Bay Area

70

Applications

Bridge networks

Node (Intersection)

Highway Bridge

Highway Segment

N5 mi

10 km

N1

N2

N3

N4

N5

N6 N7

B1

B2B3 B4 B5

B6B7B8

B9

B10-11

B12B13

B14-15B16

Saydam et al. (2013a)

71

Applications

Ships

Sea Fighter (FSF – 1)

High Speed Vessel (HSV-2 Swift)

Other engineering systems Movable bridges

Bridge – ship interaction

Gokce et al. (2013) Gokce et al. (2013)

Gokce et al. (2013)

Wikipedia (2008)

GenDisasters (2013)

Sustainability of Bridge Networks under Earthquake and Flood-Induced Scour

72

Lehigh University Bethlehem, PA, USA

You Dong, Dan M. Frangopol, and Duygu Saydam

June 16-20, 2013

73

Infrastructure systems are critical for the economy and society. The probabilistic time-variant risk assessment under multiple hazards is a relatively new research area.

The sustainability aims to improve the quality of life for present and future generations. There is the need for well established methods for quantifying the metrics of sustainability.

Social

Environmental

Economic

Adams, 2006

Sustainable

74

• Flowchart for Hazard Risk Assessment

1. Hazard Analysis Seismic Scenarios

2. Structural Analysis Seismic Demand and Capacity

3. Damage Analysis Damage States

4. Loss Analysis Monetary Loss

Probabilistic Time-Dependent

Probabilistic and Time-Dependent SUSTAINABILITY

Proposed Flowchart

Compute the total risk and use this information in

decision making

Identify seismic scenario events reflecting seismic

activity of the region

Compute economic metrics (e.g., repair cost)

Compute social metrics (e.g., downtime)

Compute environmental metrics (e.g., carbon dioxide emissions)

Seismic performance quantification of

network link

REP

EAT

FOR

EA

CH

LIN

K

Single bridge Seismic fragility

analysis

REP

EAT

FOR

EA

CH

BR

IDG

E

Compute economic loss (e.g., replacement

and repair cost)

Compute social loss (e.g.,

downtime)

Compute environmental loss (e.g., carbon dioxide

emissions)

Bridge Damage Index

Link

D

amag

e In

dex

Brid

ge

Dam

age

Stat

e

REP

EAT

FOR

EA

CH

TIM

E ST

EP

76

Bridge highway segments

4 nodes and 16 bridges

N

Orange County, CA

2Mile

0

0 2Kilometer

33.7000 N

33.5400 N

33.6200 N

117.9000 W 117.6700 W117.7850 W

LegendRoad linksNodes connecting the links

Bridges

B1B2

B3B4

B5 B6B7

B8B9

B10 B11

B12

B13

B14

B15B16

: Single-Span Simply-Supported Concrete : Multiple-Span Continuous Concrete : Multiple-Span Discontinuous Concrete

77

N

Orange County, CA

2Mile

0

0 2Kilometer

33.7000 N

33.5400 N

33.6200 N

117.9000 W 117.6700 W117.7850 W

LegendRoad linksNodes connecting the links

Bridges

B1B2

B3B4

B5 B6B7

B8B9

B10 B11

B12

B13

B14

B15B16

∑=

=n

jj tBDItLDI

1

2))(()(

The seismic performance of the link (LDI) depends on the damage states of the bridges in the links.

HAZARD ANALYSIS

78

Hazard analysis

Example: seismic hazard

Probability of occurrence

Effect on structural vulnerability

Poisson process Fragility analysis

1

1

Probability of exceeding a damage state

Peak ground acceleration (g) 0

Age of the structure increases

t = 0 years

t = 30 years

t = 60 years

79

The conditional probability of exceeding moderate damage state under PGA = 0.5g is about 0.64 at t = 25 year; this value reaches 0.87 at t = 75 years without scour. This value is 0.95 at t =75 years with flood-induced scour.

The findings highlight importance of considering effects of aging and flood-

induced scour on the seismic vulnerability of

bridges. 0 0.2 0.4 0.6 0.8 1

0

0.2

0.4

0.6

0.8

1

25 Years

Exce

edan

cePr

obab

ility

Peak Ground Acceleration (g)

Moderate Damage

Without Flood-Induced ScourWith Flood-Induced Scour

25 Years

75 Years

75 Years

Type B Bridge: Fragility Curve

Time Effects+ Flood-Induced Scour )1()( 210 Scourii Ztmtm ⋅−⋅−⋅= γγ

80

The expected economic loss increases with time and reaches the maximum value at the end of the time-interval under investigation. The difference between the cases with and without flood-induced scour increases with time.

0 25 50 750

4

8

12

16

Time (years)

Expe

cted

Los

s (U

SD M

illio

ns)

Time-Variant Expected Economic Loss

Without Flood-Induced Scour

With Flood-Induced Scour

Expected Annual Economic Loss Bridge Network

81

CONCLUSIONS

1. Effective and practical methods for capturing system performance including redundancy and robustness in a time-dependent context will continue to present an important challenge.

2. Development of prediction models for the structural performance assessment and prediction with higher accuracy will improve the results of any optimization process. Incorporation of SHM in this process is a field in its infancy.

3. Improvements in probabilistic and physical models for evaluating and comparing the risks and benefits associated with various alternatives for maintaining or upgrading the reliability of existing structures are needed.

FUTURE CHALLENGES

Acquire reliable data and develop advanced computational tools in order to :

• PROVIDE BETTER KNOWLEDGE ON DEGRADATION AND

PERFORMANCE OF CIVIL AND MARINE INFRASTRUCTURE SYSTEMS

• SUPPORT BETTER DESIGN METHODS AND

PERFORMANCE PREDICTIVE MODELS • SUPPORT ADVANCED MANAGEMENT DECISION-MAKING

TOOLS

83

IABMAS Italian Group – Milan, Italy | October 14-15, 2013

84 IABMAS Conferences

Report of IABMAS2012

IABMAS 2014

IABMAS 2014 will be held in Shanghai, China on July 7-11 2014

IABMAS 2016

IABMAS 2016 Iguazu Falls

Paraná, Brazil June 26 – 30, 2016

National Groups of IABMAS

Portuguese Association for Bridge

Maintenance and Safety www.ascp.pt

China Group of IABMAS www.iabmas-cg.org

IABMAS Italian Group – Milan, Italy | October 14-15, 2013

89 89

IABMAS Italian Group

Foundation Meeting Regina Palace Hotel, Azalea Room

Stresa, Lake Maggiore, Italy | July 9th, 2012

THANK YOU