Towards Performance Towards Performance Based Civil EngineeringBased Civil Engineering

Emin Aktan and Frank Moon Emin Aktan and Frank Moon

Drexel University, Philadelphia, PA

11th Transportation EngineeringAnd Safety Conference September 6-9, 2005

December 7, 2005

ASCE-SEI Technical Committee (1999-2005): Performance-Based Design and Evaluation of Civil

Engineering Facilities

Purpose: Facilitating the development and adoption of realistic and reliable performance-based techniques. Establish the foundations for specifications, model codes and commentaries for performance-based design and evaluation.

Aktana, Alampallig, Arzoumanidesp, Berteroa, Bettia, Brennerp, Burkep, Catbasa, Chaseg, Chongg, Dasp, Dusenberryp, Farrarg, Fenga,Frangopola, Fujinoa, Garretta, Ghandeharia, Haldara, Jonesa, Inmana, Kareema, Khindap, Kratkyp, Muftia,C, Pinesa, Satoa,J, Shinozukaa, Sozena, Wanga, Wenzelp,E, Winterfeldta,Yanevg , Zimmermana

a Academic, p Practicioner, g Government, C, E, J Liaison

Performance-Based ?Civil engineers design, construct and manage very large and complexsystems that frequently cannot be entirely conceptualized and accurately characterized. Lifecycles range between 50-500 years. Operational demands and actions may be estimated only with greatuncertainty.

In the US, common civil infrastructure facilities such as buildings, bridges, pavements, etc are often designed by prescriptive codes and constructed in a process-oriented manner by a large number of fragmented sub-industries, and these facilities are regularly deliveredwith a 1-year or no warranty of performance.

Operation, maintenance and management are often detached from design and construction and are also disconnected from each other.

AUTOMOTIVE, AEROSPACE, ELECTRONICS, etc. ENGINEERS

HAVE ADOPTED PERFORMANCE-BASED APPROACHES ......

Opposite poles

• Performance Based:

An acceptable level of protection against structural failure under extreme load shall be provided

• Prescriptive Specification:1/2” diameter bolts

spaced no more than 6 feet on center shall anchor the wood sill of an exterior wall to the foundation

From: JR Harris, P.E., PhD, 2002 Structures Congress, Performance-Based Structural Engineering: A Review

HISTORY OF US DESIGN SPECIFICATIONS: 1916: Report on Recommended Practice and Standard Specifications for Concrete and Reinforced Concrete (by ACI, American Institute of Architects, American Railway Engineering Association,ASCE, ASTM)1926: First AISC Steel Construction Manual1927: First earthquake provisions for design in the UBC1931: First Standard Specifications for Highway Bridges by AASHO1976: Unified Standard Code of Practice for Structures, by the Inter-Association Joint Committee for Safety of Structures in Europe1978: ATC 3-06 "Tentative Provisions for the Development of Seismic Regulations for Buildings"1986: First AISC Steel Construction Manual based on LRFD 1987: ATC-14 "Evaluating the Seismic Resistance of Existing Buildings"1994 AASHTO LRFD Bridge Design Specifications1994 Report to CALTRANS by the Seismic Advisory Board "The Continuing Challenge- The Northridge Earthquake of January 17"

Evolution of CE Design Philosophy • Stress design• Strength design

• Limit-States design: Acceptable failure probabilityFor loads/actions and strength of materials:

– Level 1 Semi-probabilistic (characteristic values)– Level 2 Element level (idealized distributions)

– Level 3 System level (actual distributions)Modeling and analysis procedures:

– Linear for service limit-states– Nonlinear or plastic for ultimate

• Utility, Serviceability and Durability not yet sufficiently

addressed by codes, designer knowledge/experience

and creativity a necessary ingredient for success

SOME PROBLEMS WITH CURRENT DESIGN SPECS

The rationale and the heuristic knowledge-base underlying the "specification-based" approaches has served civil engineering design and evaluation practice reasonably well during the last Century.

However, past approaches to design, construction and evaluation of constructed facilities based on prescriptive codes and qualitative descriptions of performance have become inadequate for many projects.

The cost for maintaining the infrastructure has reached objectionable levels. Societal expectations from infrastructure delivery are changing: Design-Build, Design-Build-Warrant, Finance-Design-Build-Operate, etc

New sizes, systems, materials, processes and use-modes that are notcodified cannot be easily introduced.

Metrics and associated objective-measurable indices are required for: Performance, Condition, Health, and Damage so that we may take proper advantage of integrated asset management approaches to entire infrastructure systems.

CODE COMMENTARY STATEMENTS:

CALTRANS seismic criteria:

These criteria indicate that the permissible damage and post-earthquake service

required for "ordinary" bridges following a "maximum credible earthquake" are

"significant" and "limited" respectively.

AASHTO LRFD Bridge Design Specifications:

The structural system of a bridge shall be proportioned and detailed to ensure

the development of significant and visible inelastic deformations at the strength

and extreme event limit states prior to failure.

While explicit descriptions for performance expectations are available for

buildings and bridges at the ultimate limit-states, these remain subjective,

qualitative and nebulous. Measurable, meaningful indices are lacking.

What’s Wrong with SuchPerformance Statements?

• Quantitative criteria are needed

– Sometimes difficult to formulate

– Often difficult to achieve consensus

• Evaluation procedures – Measurement is key; must find a way to

measure (analytically or experimentally) a meaningful quantity

From: JR Harris, P.E., PhD, 2002 Structures Congress, Performance-Based Structural Engineering: A Review

Hamilton Co. (OH) Bridge (1997)Over 24 subcontractors for construction Many Bureaus of ODOT and District 6

Price: $ 1,000,000 - $2,000,000

Performance Metrics: ??

Warranty: None

Process-Oriented Approac

Auto and Construction: The Need for Metrics

2001 Small Car

Price: $ 12,000

Performance Metrics !

Warranty Bumper-to-bumper: 5 yearsPowertrain: 10 years

Product-Oriented Approach

CRITICAL INFRASTRUCTURE SYSTEMS

• Telecommunications• Electric Power• Gas and Oil Storage and Delivery• Transportation• Water Supply• Food and Agriculture• Medicine and Health Care• Chemical Industry• Banking and Finance• Emergency Services• Government

Natural Environment

Human Elements

EngineeredElements

Maintenance

EngineeredSystems

NaturalSystems

HumanSystems

Construction

Integrated Design - Construction -Operation - Maintenance Systems

Constructed Systems at Intersection Shaping Infrastructure

Life-Cycle Performance

Design

Detached Design - Construction -Operation - Maintenance Systems

Sub-Systems Affecting Infrastructure Life-Cycle

Performance

Operation

ConstructionDesign

Construction

Maintenance

Operation OperationMaintenance

Design

Multi-Dimensional Performance Matrix for Infrastructures

ProtectionQuality of lifeLeveraging science, engineering and technology for society

HarmonyAestheticsAdvancing engineering and science education

SocietalObjectives

RecyclableAdaptabilityConditional events (w/very long return)

DeteriorationMaintainabilitySafety & stability of failure

AgingInspection & evaluation

Serviceability & durability

Engineering Limit States

Hazardous waste (chem, bio, etc.)Fiscal responsibilitySecurity

Env. FriendlyMulti-hazard risk managementEfficiency

SustainableOrganizational efficiencySafety

Operational and Utility Limit States

NatureSocial-Technical Elements

Engineering Elements

Performance Category:

Lack of multiple escaperoutes in buildings Lack of post-failureresiliency leading toprogressive collapse ofbuildings Cascading failures ofInterconnectedinfrastructure systemsFailures of Infrastructureelements critical foremergency responsemedical, communication,water, energy,transportation, logistics,command and control

Excessive:movements;settlements;geometrychanges

Material Failure

Fatigue

Localized or Member LevelStability failure

Excessive:Displacements;Deformations;Drifts

Deterioration

Local damage: Cracking, Spalling, Yielding

Excessive Vibrations

Environmental impacts

Social impacts

Sustainability of functionality throughout life cycle

Financing Initial cost and life cycle costs

Operational capacity safety, efficiency, flexibility and security

Feasibility of construction, protection and preservation

Aesthetics

Stability of Failure

Incomplete orpremature collapsemechanism(s)without adequatedeformability andHardening; Undesirablesudden brittlefailure mode(s)

Lack of Durability

Special limit statethat should governaspects of globaldesign, detailing,materials andconstruction

Substantial Safety at Conditional Limit States

Life Safety and Stability of Failure

Serviceability and Durability

Utility andFunctionality

Limit State

Design Limit States and Limit EventsLi

mit

Even

ts

War, TerrorismExtremely rare load

500 year100 yearFlood

Sustained fireExtreme cold or fire

Above normal heat and cold cycles

Average heat and cold cycles

Temp

2% excedencein 50 years

10% exceedencein 50 years

50% exceedencein 50 yearsEarthquake

Hurricane, tornado

Strong windstormTypical windWind load

Live load exceeds design

Live load = design live load

Typical occupancyLive load

Sustained, with remodeling

Sustained as designedDead load

Extreme (2500-5000)

Rare (205-500)Occasional (5-25)

Normal (0)

Frequency (Return Period in Years)Demands

Typical Design Loads and Their Frequency

Define Performance in terms of Health?Health = Reliability of bridge system to possess adequate capacity against any limit state demands at any time throughout its lifecycle

Health = (1-P f ) /for All Limit-State Demands /T<Lifecycle / As-Is Condition/Operational and Maintenance Management/

If ββ is 2nd Moment of (1-P f ): Reliability Index

β β = 0; (1-Pf) = 0.5, ββ = 3; Health = 0.999,

ββ = 4.75 Health = 0.99999, i.e. 10 -6 chance of failure

10-710-610-5Large (>10)

10-6

(β = 4.5)10-510-4

(β = 3)Medium

10-510-410-3Small (1<)

Very HighHighInsignificant

Economic ConsequencesPopulationAt Risk

Recommended Probability of Failure Levels for Ultimate Limit States (CEB-FIP 1978)

Typical Events Causing 500 Bridge Failures in Last Decade

• Hydraulic Events

• Collision

• Overload

• Deterioration

• Fire

• Construction

• Ice

• Earthquake

• Fatigue

• Design Errors

• Soil

• Storm/Hurricane/ Tsunami

• Beta=3

(Wardhana & Hadipriono, ASCE Journal of Performance of Constructed Facilities, 2003)

TENTATIVE PROCEDURE FOR DEVELOPING PERFORMANCE METRICS:

Review and Synthesis of Existing Standards and Heuristics.

Classify common constructed systems into population groups the

performance of which are governed by similar design, construction,

location, condition and use parameters.

Formulate and Describe Performance Metrics for a population

group that may be represented by a statistical sample.

Observation and Measurement of Reality for statistical samples:

System identification and health monitoring of statistical samples.

Quantification and Optimization of the Performance Matrix.

Incentives for Field MeasurementsIncentives for Field MeasurementsRobert Robert MaillartMaillart (1907):(1907): Designers should check their Designers should check their assumptions through load tests for deflections assumptions through load tests for deflections

Construction:Construction: Monitoring may be incorporated in design for Monitoring may be incorporated in design for optimum intrinsic forces, control of construction processes and optimum intrinsic forces, control of construction processes and its impacts, construction quality control, retrofit constructionits impacts, construction quality control, retrofit construction

Establish asEstablish as--builtbuilt properties at commissioning to serve as a properties at commissioning to serve as a baseline for properties from future tests as may be warranted baseline for properties from future tests as may be warranted

Evaluate: Evaluate: performance problems, vulnerability, permits, performance problems, vulnerability, permits, rate/rerate/re--qualify, life expectancy, retrofit, postqualify, life expectancy, retrofit, post--event conditions event conditions

Changes in: Changes in: loads, useloads, use--mode,mode, codes, expected eventscodes, expected events

Health MonitoringHealth Monitoring for proactive management for proactive management

Research and EducationResearch and Education of renaissance civil engineersof renaissance civil engineers

Classification of Experimental Tools Classification of Experimental Tools

GeometryGeometryMeasureMeasure--

mentment

Local Local NDENDE Load TestingLoad Testing

(Static or Quasi(Static or Quasi--Static Testing)Static Testing)

ControlledControlled UncontrolledUncontrolled

Static Static TrucksTrucks

Crawling Crawling TrucksTrucks

Measure Measure Outputs Outputs

OnlyOnly

Measure Measure Input by Input by WIM & WIM & OutputsOutputs

Vibration Analysis Vibration Analysis (Dynamic Testing)(Dynamic Testing)

ControlledControlled UncontrolledUncontrolled

Measure Measure Outputs Outputs

OnlyOnly

Measure Measure Input & Input & OutputsOutputs

Input by Input by TrafficTraffic

ImpactImpact

ForcedForced--Vibration Vibration

by by ExciterExciter

SurveyingSurveying

GPSGPS

LaserLaser

Remote Remote SensingSensing

Photo Photo MethodsMethods

Material Material TestingTestingThermalThermal

MagneticMagnetic

UltrasonicUltrasonic

AcousticAcoustic

ElectricalElectrical

OpticalOptical

ElectroElectro--ChemChem

NuclearNuclear

Special Special Loading Loading DevicesDevices

Measure Measure Input & Input & OutputsOutputs

Input by Input by Traffic, Traffic, Wind, Wind,

SeismicSeismic

Input by Input by TrafficTraffic

ShortShort--Term (Hours) Structural TestingTerm (Hours) Structural Testing

Classification of Experimental Tools Classification of Experimental Tools

LowLow--Bandwidth Bandwidth MeasurementsMeasurements

HighHigh--Bandwidth Bandwidth MeasurementsMeasurements

LongLong--Term Monitoring (Months Term Monitoring (Months –– Decades)Decades)

VibrationsVibrationsConstruction EffectsConstruction Effects

Traffic LoadsTraffic LoadsWind/Ambient Weather ConditionsWind/Ambient Weather Conditions

TemperatureTemperature

Movements or DisplacementsMovements or DisplacementsOperationsOperations

Incidents or AccidentsIncidents or Accidents

ImpactsImpacts

EarthquakeEarthquake

Security MonitoringSecurity Monitoring

Mechanical Variables (Force, Mechanical Variables (Force, Stress, Strain, etc)Stress, Strain, etc)

Changes in: Geometry, Changes in: Geometry, ElectroElectro--chemical Propertieschemical Properties

Deterioration/Damage EffectsDeterioration/Damage Effects

Semantic Models•Ontologies•Semiotic ModelsMeta Models•Rule-based meta Models•Mathematical (Ramberg-Osgood, etc.)Numerical Models•Probabilistic Models- Histograms to Frequency Distribution- Standard Prob. Distributions- Independent events- Event-based (Bayesian)- Time-Based (Markov)- Symptom-based•Agents: Meta + Monte Carlo•Statistical (Data-Based)- ARMA, ANN, others- Signal/Pattern Analysis, Wavelet, etc

Mathematical Physics Models•F=MA•E=MC2

Continua Models•Theory of Elasticity•Field and Wave Eqns•Idealized Diff. Eqns (Bernoulli, Vlasov, etc.)Discrete Geometric Models•Smeared-Macro or Element Level Models•FEM-for Solids and Field Problems•Modal Models:- Modal Parameters- Ritz VectorsNumerical Models•K,M,C Coefficients

Non-Physics-Based Models Physics-Based Models

MODELING ALTERNATIVES FOR CONSTRUCTED SYSTEMS

Experimental Technologies

Analytical Technologies

Analytical Modeling Macro- Element-FE

CAD-Reverse CAD Linear Analysis

Static Moving Dynamic

Non-linear AnalysisPush-to-Collapse

Geometry Material

Information TechnologiesData Acq,

Transmission, Synchronization,

and Quality Assessment

Data Processing, and Visual Display

Data Archival,Warehousing, and Analysis

DataInterpretation

Knowledge Wisdom DecisionInformationData

Geometry Monitoring

Controlled Testing

NDE Material/Characterization

SCADA SystemMonitoring

Systems Integration:

Experience

Clermont BridgeNon Destructive And

Destructive Testing Of A Concrete Slab Bridge and

Associated Analytical Studies(1990-1992)

40-year Old RC Slab Bridge

Servo-Controller and Data Acquisition Hardware in Field Office

Loading System

Shear Failure Triggered By Deterioration

Chem Deterioration of Concrete

D-Cracking and Alkali-Silica Reaction

Load-Displacement Test Response

Nondestructive/Destructive Tests and Associated Studies on

Two Aged, Decommissioned Steel Truss Bridges

(1992-1994)

Pratt Bridge

Camelback Bridge

Alkire Bridges

Load Transfer System Chord Failure

Pratt Bridge Camelback

Bridge

Nondestructive Testing and Identification for

Bridge Rating (1988-1993).

Reading RoadBridge

c

ccc

Bridge HealthMonitor

WIM ScaleMonitor

WeatherStation

TrafficCameraRemote Monitoring

Station

Pier 1Pier 2 Abut 1Abut 2

HAM-42-0992 Westbound

Concrete GagesRosette Strain Gages

Vibrating Wire Gage ClusterFoil Gage Cluster (Type 1)

c

type 1type 2type 3

Foil Gage Cluster (Type 3)Foil Gage Cluster (Type 2)

Site Design for Bridge Monitor System

-100

-50

0

50

100

150

200

250

Sep-94 Jan-95 Apr-95 Jul-95 Oct-95 Feb-96 May-96 Aug-96 Dec-96

Date

Mic

rost

rain

0

20

40

60

80

100

Tem

pera

ture

(F)

Ambient Temp. DEGF

PIER

MID

SPAN

ABUT

MEN

T

Two Year Continuous Monitoring Results(Nov 94-Nov 96)

∆T=111.4 F

∆ε =359 µε

Sampling: 1sample / 6 hours

Instrumentation of Steel Grid Superstructure

Data Acquisition Cabinet

for Teleremote On-Line

Monitoring of In-Service

Responses

Instrumentation, Testing and Monitoring of a Newly

Constructed Reinforced Concrete Deck-On-Steel

Girder Bridge (1994-1998).

Hamilton Bridge

Deck Pouring Operation

RC deck Embedment Sensors

Instrumentation of the Stringers

Pile Instrumentation

Heat-Camber Instrumentation

View Under the Deck

ANALYTICAL MODELING FOR ACCURATE SIMULATION

Bridge Ham 42-0992

LINK ELEMENTS

5150 D

OF'S

(a) 3-D FEM

(d) Pier

VERTICALSPRINGS

BEAM ELEMENT

SHELL ELEMENT

LINK ELEMENT

LINK

LINK BEAM ELEMENTVERTICAL SPRING

ROTATIONAL SPRINGSBEAM ELEMENT

LINKELEMENT

SHELL ELEMENT

LINK ELEMENT

(c) Abutment

BEAM ELEMENT

SHELL ELEMENT

BEAM ELEMENT

(b) Slab, Girders, and Cross-Braces

SLAB &CROSS BRACES

(BEAM ELEMENT)

SLAB &GIRDERS

(BEAM ELEMENT)

(a) 2-D Grid

(b) Slab, Girders, and Cross-Braces

(c) Equivalent Beams

LONG

ITUDIN

AL B

EAMTRANSVERSE BEAM

500 DOF'S

Bridge Characterization through Grid Model

Bridge Characterization through FE Model

Bearing Pad Detail Over Pier

Abutment Detail

ABUTMENT

PIER

Flexibility Change Due to Pads

-0.010

DEF

LEC

TIO

N (I

N.)

-0.008

-0.006

-0.004

-0.002

0.000

WESTPIER

EASTPIER

OCT. 1991 AUG. 1997

BGCI INDICATES CHANGEAT WEST PIER BRGS.

BGCI GIRDER 2 N

FALL 1991 SUMMER 1997

UPLIFT

Figure 13: Bridge Girder Condition Index Results

Damage Scenarios: Steel SuperstructureOne-Sided Flange Cut Two-Sided Flange Cut

Crossframe CutsWeb Cut

Bridge-Type Specific Management of Steel-Stringer Bridges in Ohio

(1996-1998)

Seymour BridgeTransforming a bridge into a laboratory:

-0.006

-0.002

0.00

1 kip/point

Deflection, in.

NDamage Location

-0.004

3.823.81

3.85

After X-Brace Cut4.33 3.69

Modal Flexibility Based Deflections (BGCI)

After X-Brace Cut at South SpanWelding/Restoration of BC's

5.09

Test (Baseline)

Flex Coefficient = 0.0026 in/kip

78'

45'

55'55'50' 40'40'

40'

40'-2 1/2" 88'-5 5/8" 40'-3 1/2"

40'

Flex Coefficient = 0.0025 in/kip Flex Coefficient = 0.0021 in/kip

Reading Road Bridge, Cincinnati, OH

Cons. Year 1997

Hamilton Ave. Bridge, Cincinnati, OH

Seymour Ave. Bridge, Cincinnati, OH

Cons. Year 1953 Cons. Year 1989

FLEXIBILITY COEFFICIENTS FOR STEEL-STRINGER BRIDGES

78'

45'

55'55'50' 40'40'

40'

40'-2 1/2" 88'-5 5/8" 40'-3 1/2"

40'

Reading Road Bridge, Cincinnati, OH

Cons. Year 1989

Hamilton Ave. Bridge, Cincinnati, OH

Seymour Ave. Bridge, Cincinnati, OH

Cons. Year 1953

HS20-44 Loading(8 kips+32 kips)

Measured Deflection:0.0724 in

L/800: (AASHTO)0.0975 in

COMPARISONS FOR STEEL STRINGER BRIDGES

Cons. Year 1997

Freqs (Exp) 4.94 Hz5.30 Hz7.47 Hz

HS20-44 Loading(8 kips+32 kips)

Measured Deflection 0.0827 in

L/800: (AASHTO)0.0625 in

Flex Coeff. 0.0021 in/kip

HS20-44 Loading(8 kips+32 kips)

Measured Deflection:0.0846 in

L/800: (AASHTO)0.1106 in

Freqs (Exp) 4.55 Hz5.14 Hz7.95 Hz

Freqs (Exp) 7.16 Hz8.06 Hz8.82 Hz

Flex Coeff. 0.0026 in/kip

Flex Coeff. 0.0025 in/kip

MECHANISMS GOVERNING BEHAVIOR OF THE READING ROAD BRIDGE HAM-42-0992

NONCOMPOSITE

D=1.19"

D=0.67"

COMPOSITE

D=1.71"

W/O DECK

D=2.00"

W/O DECK & X-BRACES

PRE-725-0800

BUT-732-1043

HAM-27-1550LHAM-27-1550R

CLE-52-0498RCLE-52-0498L

Locations of 6 Bridges:Locations of 6 Bridges:State of OHIO, District and Counties MapState of OHIO, District and Counties Map

(Courtesy of Ahmet Turer, METU)

54'-0" (L) 67'-6" (L)

4 Spaces @ 9'-6"= 38'-0"

(L and R)

Varies

Varies

54'-0" (L)60'-0" (R) 75'-0" (R) 60'-0" (R)

Crossframes12 spaces @ 13' = 156' (L)

14 spaces @ 12'-3" or 13'-3.5" = 175'-8" (R)

HAM-27-1550L and R

BUT-732-1043

4 spaces@ 8'-4 1/2"

= 33'-6"

60'-0" 75'-0" 60'-0"

Crossframes18 spaces @ 10'-10" = 195'

1'-4"

1'-4"

CLE-52-0498L and R

68'-0"(L and R)

85'-0"(L and R)

68'-0"(L and R)

2'-4"

5'-6"

Crossframes18 spaces @ 12'-3 1/3" = 221'-0" (L and R)

1'-7"

4 spaces @ 7'-6"= 30'-0" (L and R)

Bridge Age Skew Deck Width Length* Span Ratio Gen. Insp.PRE-725-0800 30 yrs (1968) 10 deg. 38'-0" 192'-0" 0.7L, L, 0.7L 6HAM-27-1550L 28 yrs (1970) 9 deg. 42'-0" 175'-6" 0.8L, L, 0.8L 7HAM-27-1550R 28 yrs (1970) 9 deg 42'-0" 195'-0" 0.8L, L, 0.8L 7BUT-732-1043 46 yrs (1952) 0 deg 36'-2" 195'-0" 0.8L, L, 0.8L 6CLE-52-0498R 33 yrs (1965/91) 0 deg 39'-5" 221'-0" 0.8L, L, 0.8L 7CLE-52-0498L 33 yrs (1965/91) 0 deg 39'-5" 221'-0" 0.8L, L, 0.8L 7

PRE-725-0800

12' 12'Crossframes

14 spaces @ 12' = 168'

56'-0" 80'-0"

2'-3"4 Spaces

@ 8'-4 1/2"= 33'-6"

56'-0"

2'-3"

Comparison of BARS and Grid/FEM Based Rating Factors (ASD, Inventory, Nominal)

y = 2.0425xR2 = 0.6687

y = 1.9363xR2 = -2.8752

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

BARS Rating Factors

Cal

ibra

ted

Grid

/FEM

Mod

el B

ased

Rat

ing

Fact

ors

BARS vs FEMBARS vs GridBest FitBest Fit

(Courtesy of Ahmet Turer, METU)

Steel-Girder Bridge Population ManagementDESIGN SYSTEMS

?

?

?

?

?

?

?

HYDROLOGY

DRAINAGE

?

?

?

? PAVEMENT

FOUNDATION ?

ABUTMENT ?

PIER

BEARING

BEAMS ?

X-FRAMES ?

DECK ?

MOVEMENT ?

SOIL

PERFORMANCE SYSTEMS(OPERATION)

SERVICEABILITY

DURABILITY

MAINTAINABILITY

FATIGUEREDUNDANCYFAILURE MODES

CONCRETESTEELDETAILS (BRGS., PINS, ETC.)

INSPECTIONPAINTMOVEMENTOVERLAYSDRAINAGELIFE-CYCLE COST

STRESSESDEFLECTIONSCRACKINGVIBRATIONSAESTHETICS

ORGANIZATIONAL SYSTEMS

DESIGN

CONSTRUCTION

OPERATION

INSPECTION

RATING

PERMITS

MAINTENANCE

REHAB/RETROFIT

DECOMMISSION/RENEWAL

MANAGEMENT

FINANCING

FEASIBILITY & IMPACT

PLANNING

SAFETY

OPERATIONS

Instrumentation, Proof-Testing and

Monitoring of Three Reinforced

Concrete Deck-on-Steel Girder Bridges Prior to, During

and After Superload

(1996-1997)

Toledo Super-Load

Loaded Truck Crossing A Bridge Close-Up of

Superload

Correlations Between The Super-Load Measurements and Simulations Obtained From FE Analyses

Instrumenting bridges by strain, tilt and

displacement sensors

Nondestructive Condition Assessment of a Posted

Bridge(1996-1997)

Tindall Bridge Top Chord and Instrumentation Details

Floor Grate Compression- Strut-to-Lower-Chord Joint Deterioration

Micro-Sampling Technique FE Modeling for Sample Locations

Scanning Electron Miroscope Photos:

Aged Steel With Corroded Layer

Contemporary Steel

Tindall Bridge

Two-span 1927

1922

UNIVERSITY

Profile of T-Beam Bridges in Pennsylvania

Total Number in USA > 32,000Total Number in PA >2600Type Specific Design

Built Between ~1930 & 1950Span ~20 ft -40 ftWidth ~ 20 ft - 40 ftSkew ~ 0 - 45 degSlab Thickness ~ 8-8.5 inBeam Spacing ~ 5 ft on centerBeam Depth ~ 19 in - 40 in

Standard Design Dwgs.

1,651 Single Span T-beam Bridges in PA

Statistical Representative 60 T-Beam Bridges

Entire 1,651 T-Beam Bridge PopulationStatistical Representative 60 T-Beam Bridges

< 192930%

1929 to 193830%

1939 to 194817%

> 194823%

Year Built

201 to 55031%551 to 1000

17%

1001 to 500027%

0 to 20022%

> 50003%

Average Daily Truck Traffic

Skew Angle (degrees)

16 ft to 32 ft62%

33ft to 40ft18%

41 ft to 55 ft20%

> 500%

0 to 743%

8 to 2218%

23 to 3722%

38 to 5017%

Skew Angle(degrees)

536%

623%

7 to 818% 4

20%

33%

Year Built

1929 to 193834%

< 192924%

> 194824%

1939 to 194818%

Skew Angle (degrees)

> 501%

8 to 2219%

23 to 3722%

38 to 5020%

0 to 738%

Span(Width

Dependent)

16 ft to 32 ft64%

33ft to 40ft22%

41 ft to 55 ft14%

Average Daily Truck Traffic

0 to 20050%

201 to 55025%

551 to 100010%

1001 to 500012%

> 50003%

37%7 to 8

15%

617%

427%

534%

SuperStructure Condition

Rating

Span(Width

Dependent)

Nominal Structural Parameters Condition Parameters

SuperStructure Condition

Rating

Entire 1,651 T-Beam Bridge Population

STATISTICAL SAMPLING OF T-BEAM BRIDGES

Churchville Road Bridge, PA

Academy Road Bridge, PA

Coring of the deck

Manoa Bridge, PA

Core Samples

SAMPLE T-BEAM BRIDGES

Cross Section of the Model

16.85”

15.5”

15.75”

8.5”

Reinforcement

Statistics of The Model:Number of DOF =108243Number of Solid Elements = 22940Number of Frame Elements = 7636

T-Beams

Parapet

End Diaphragm

Structural Details & Boundary Condition

3.375”

3.375”12”

3.375”

3.375”12”

Typical Solid ElementDimensions

Pin End

Roller End

UNIVERSITY

Details of the Swan Road Bridge Finite Element Model

Transverse Centerline Deflection of the Superstructure (Test vs. Models)

Def

lect

ion

(in)

-0.010

-0.020

-0.030

0

-0.040

-0.050

-0.060

-0.070

Section A-A

A2 B2 C2 D2 E2 F2

K K

K = 1000 kip/in

K K

K = 1000 kip/in

Boundary Condition Idealization of Different Models:

Displacement Sensor Location

A-A

A B C D E F

3

2

1

CL

CL

Truck and Sensor Locations:

-0.010

-0.020

-0.030

0

Def

lect

ion

(in)

-0.040

-0.050

-0.060

-0.070

Deflection of the T-Beam "C" (Test vs. Models)

Superstructure

C3 C2 C1

Section B-B

B-B

UNIVERSITY

Regional Calibration-Deflections of the Swan Road Bridge & Test Results

H20 Truck

d) Field-calib. FEM w/o Concrete Deck Rating Factor: RI=2.18, RO=3.63

a) AASHTO based BAR7 Analysis Rating Factor: RI=1.27, RO=2.11

b) Field-calibrated FE Model Rating Factor: RI=3.18, RO=5.32

f) Damage and Deterioration Case 2 (Case e and only vertical restraints at the inner edge of the boundary)

Rating Factor: RI=1.05, RO=1.76

c) Field-calib FEM w/o Parapet and Sidewalks Rating Factor: RI=3.10, RO=5.18

e) Damage and Deterioration Case 1 (40% of concrete, only 80% of upper layer rebar)

Rating Factor: RI=1.16, RO=1.93

H20 Trucks

UNIVERSITY

Comparison of Different Model Load Rating Results

Mechanisms Contributing To 2.5 - 5 Times Capacity Rating Relative to Current Practice

(Limit Condition: First Yield in Steel)

v Demand Mechanisms• Compression due to Pavement

Thrust and Soil Pressure

• Boundaries Partially Restrained For Displacement and Rotation Due to Geometry and Dowels

• Reinforced Concrete Parapets

• Stiff Diaphragm Beams

• Lateral Load Distribution by Slab Is More Effective than simulated by DF

• Effective Force Redistribution Due To Cracking Not Incorporated

v Capacity MechanismsNot Incorporated in RF

• Bi-axial Compression State of Concrete Stress due to Restrained Boundaries

• Higher Yield Strength, Statistical Strength and Post-Yield Strain Hardening of Steel

• Multiple Rebar Layers

• Yield Line Capacity of Slab

Long-Span Bridges: St-ID

Conceptualize

A-Priori Modelingfor Exp Design

Utilization

Monitoring and Controlled Tests

Calibration,Parameter Id Process and

Interpret Data

1

3

2

45

6

Analytical Modeling and Simulation

Observation and Experiment

Conceptualization and FEM ProcessDesign Drawings

Photograph

CAD Model

Structural Model

Drawings

PP27

Upper Chord at PP27

PP27

Panel Point 27Lower Chord at PP 27

PP27

L27U27

L27L28L26L27

L27U28

Moment Release (Axis 3)Axial Force Release (Axis 1)

Moment Release (Axis 3)

PP 27 – PlanPP 27

LowerChord

Verticals and Diagonals

Floor System

PP27

Lower Chord at PP27

Floor System

PP 27 and Floor

System

Plan View at PP27

Floor System

Ambient Vibration Test with Dense Sensor Array

45 Accelerometers

Utilized

Vert. Accel.

Long. Accel.

Lat. Accel.

Pier W1

~416'

Pier CL

Bottom Chord Level

Static and Crawl Speed Load TestStatic and Crawl Speed Load Test

5-7 mph

0 10 20 30 40 50 60 70-5

0

5

10

15

20

25

30

35

PP27

panel points

Str

ain

(mic

rost

rain

)

L1

PP36

South Hanger Strains (L1)

13'-0"13'-0" 11'-4" 11'-4" 11'-4"

987654321

N 1 2 3 4 5 S

Stringer

Time (sec) and Position of Load

Stra

in (m

icro

stra

in)

14000 200 400 600 800 1000 1200-50

0

50

100

150

200

250

PP26

1'

PP26

PP25

NorthSouth

L1

Stringer 8

PP25

Repeatability Check

L.C. 1 ( Crane A)

L.C. 7 ( Crane A+B)

L.C. 7 ( Crane A)

L.C. 4 ( Crane A)

Single Crane During Crawl Speed Test

Static Test DataFor Stringer b/wPP25-PP26

Crawl Speed TestData for Influence Line Generation

Real-time Portal: http://216.178.81.122/portal/ installed sensors and systems accessible (http://216.178.81.122/cbb sensors.htm)

Using Field-Calibrated Models and Health Monitoring By Real-Time Information Systems for Management

SECURITYSECURITY

•Traffic Enforcement

•Weight Enforcement

•Detection/Response: Incidents/Accidents

•Security Surveillance

•Emergency Response Natural and Man-Made Hazards:

•Hit & Run•Terrorism

OPERATIONOPERATION•Safety:ØWeather ØRoad SurfaceØIncidents ØAccidents

•Traffic Flow:ØE-AdvisoriesØSpeed LimitsØTruck/Auto/HOV

•Revenue:ØE-TollingØZone/Time TollØWeight-TollingØLoad PermitsØStatistical Data

MAINTENANCEMAINTENANCE• Detect and Mitigate Deterioration (corrosion)

• Detect and Intercept Damage (fatigue- crack)

• Harden for Security• Repair Unavoidable Deterioration/Damage

• Retrofit (fracture-critical)• Rapid Condition Evaluation (Post-Hazard)

Natural Environment

Operating Environment

ConstructedSystems

Henry Hudson BridgeHenry Hudson Bridge

Manhattan The BronxEAST ELEVATION

South Approach

South Viaduct

South Tower

94 m 91 m

North TowerArch Span

256 m

North Viaduct

North Approach

91 m 82 m

T

T

V

V East Side Vertical East Side Vertical AccelerometerAccelerometer

West Side Vertical West Side Vertical AccelerometerAccelerometer

East Side Transverse East Side Transverse AccelerometerAccelerometer

West Side Transverse West Side Transverse AccelerometerAccelerometer

L

L East Side Longitudinal East Side Longitudinal AccelerometerAccelerometer

West Side Longitudinal West Side Longitudinal AccelerometerAccelerometer

V T V T Sensors used in Stage 1 & Stage 2 TestsSensors used in Stage 1 & Stage 2 Tests

Instrumentation PlanInstrumentation Plan

Tow

erTo

wer

Tow

erTo

wer

CL ArchCL Arch

South South ViaductViaduct

North North ViaductViaduct

Upper Upper LevelLevel

Lower Lower LevelLevel

T T T

T

T

TT

T

T

TT

TT

TT

T

T

T

T

T

T

T

T

TT

TV

VV

V

VV

V

VV L

V

LL LL L L L

East ElevationEast Elevation

Stage 1 Test SetupStage 1 Test Setup

V

Stage 2 Test SetupStage 2 Test Setup

Sensors and Data AcquisitionSensors and Data Acquisition

Ambient Vibration Testing of the Ambient Vibration Testing of the Brooklyn BridgeBrooklyn Bridge

Accelerometer InstallationAccelerometer Installation

Performance of InfrastructurePerformance of InfrastructureWhat is so different about civil infrastructure systems?What is so different about civil infrastructure systems?

Fabricated/constructed natureFabricated/constructed natureVariations in geometric and material properties, environment, Variations in geometric and material properties, environment, site conditions, usage, age, condition, etc.site conditions, usage, age, condition, etc.Lack of objective data = significant epistemic uncertainty = Lack of objective data = significant epistemic uncertainty = greater cost & less than optimal performancegreater cost & less than optimal performance

Performance limit states for constructed systemsPerformance limit states for constructed systemsCodes consider only a few of many possible limit states Codes consider only a few of many possible limit states (Functionality, Serviceability & Durability, Safety & Stability (Functionality, Serviceability & Durability, Safety & Stability of of Failure, Safety at Conditional Limit States)Failure, Safety at Conditional Limit States)Performance Based Engineering: expected performance Performance Based Engineering: expected performance criteria for the full spectrum of limit states in the life cyclecriteria for the full spectrum of limit states in the life cycle of of a bridgea bridgeWhy is state of practice so deficient? Lack of objective dataWhy is state of practice so deficient? Lack of objective data

Health index Beta Health index Beta –– different for different limit statesdifferent for different limit states

Disaster responsePlanning;Emergency

management

Protection ofescape routes,evacuation, search and rescue needs, minimizeCasualties;EconomicRecovery (years)

Multi-hazards RiskManagement

Assurance of lifesafety and quickrecovery ofoperations following ahazard

(days-months)

Multiple-objectivePerformancefunction forintegrated assetmanagement

Functions relating to optimizing inspection,maintenance andrehabilitation during lifecycle

Multi-objective performance function for integrated asset management

Functions relating to operationalefficiencysafety andsecurity

Substantial Safety at Conditional Limit States

Life Safety and Stability of Failure

Serviceability and Durability

Utility and Functionality

Limit State

Limit States and Performance GoalsPe

rfor

man

ce C

riter

ia

Performance Indices for Bridges• Operational Safety, Security, Utility and Functionality:

– Safety - under adverse weather (ice, wind, roadway freezing)– Security Risks: Threats - Vulnerability – Consequences – Bridge versus Network operational capacities/demands – Geometric Restrictions: Lanes, Height/Width, Approaches– Criticality for the network, necessary for emergency response?– User costs and economic (GDP) impacts of bridge if closed

• Safety:– Load capacity rating (based on actual measured load distribution)– Vulnerability to Hazards (Manmade and Natural) and Risks – Redundancy and Toughness (especially for hazards)

• Serviceability, Durability– Condition rating and rate of decrease in condition rating– Deflections, Cracks, Debonding, Vibrations, Settlements– Drainage, Chlorides, Reactive aggregates, Rebar corrosion

• Feasibility of Inspection and Maintenance

Vulnerability:Probability of

Failure to Perform

Hazard:Probability of

Extreme Design

Demands Exceeded

Exposure:Consequences

of failure to perform during that limit event

Uncertainty Premium

Risk of failure to perform at a limit event

Performance-Based Design Based on Uncertainty/Risk:

Establish the resistance envelope to meet the demands at each limit-event based on an acceptable risk of failure to perform at that event i.e.:

P (Φ Capacity <= γ Demand)

Establish P for each limit-event and select Demand,actions, Φ and γ based on an acceptable risk of failure to perform at that limit-event.

Performance-Based Design and Evaluation under Uncertainty and Risk