implications of damage and deterioration on the ...€¦ · introduction according to the national...

Implications of Damage and Deterioration on

the Performance and Serviceability of Girder

Bridges – Part I: Background

Presenting by:

Devin K. Harris, Ph.D.

Assistant Professor

Department of Civil and Environmental Engineering

University of Virginia

MAUTC Webinar – November 2014

Sponsored by:

Mid-Atlantic University Transportation Centers (MAUTC)

Virginia Department of Transportation (VDOT)

Dr. Gheitasi received his Bachelor’s and

Master’s degrees in Civil and Structural

Engineering from Tehran Polytechnic, Tehran,

Iran. He received his PhD in August 2014 and

currently he is a postdoctoral research associate

in the Department of Civil and Environmental

Engineering at the University of Virginia. His

research interests include bridge engineering and

behavior, structural health monitoring, finite

element method, non-linear structural analysis,

and thin-walled structures.

Dr. Harris joined the Civil and Environmental

Engineering Department at the University of

Virginia in July 2012. He had a prior

appointment at Michigan Technological

University as the Donald F. and Rose Ann

Tomasini Assistant Professor in structural

engineering. His research and teaching interests

include bridge behavior, condition assessment

and structural health monitoring, reinforced and

prestressed concrete behavior, the application of

innovative materials in civil infrastructure, and

railroad engineering.

E-mail: [email protected] E-mail: [email protected]

mailto:[email protected]






Table of Contents

Part I: Background

Introduction

Problem Statement

Computational Modeling

Challenges

Part II: Application

Investigation Approach

Model Calibration

Parametric Study

Summary

Future Research

1 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges – Part I

Bridges: Critical component in everyday's lives of most people

Provides lifeline between communities

Controls the capacity of the system

Their failure results in:

• Global system failure

• Loss of lives

• Detours

• Economic hardships

Introduction

National Highway system: One of the greatest engineering achievements of

the 20th century.

Serves as a core component to the economic health of the United States

Provides corridor for transportation goods and people

Provides a coast to coast and border to border passageway for the nation’s military

Historically includes roads and bridges


Introduction

I-35, Minnesota (2007) I-5, Washington (2013) M bridge, Missouri (2013)

Tragic failures brought the challenges associated with the safety of the

national infrastructure to forefront of the public’s scrutiny.

Failures are often attributed to unforeseen events/ manmade hazards

Vehicle/ship impact

Fire

Flooding

Earthquake

Condition states of in-service structures:

Represent the greatest challenges for transportation agencies


Introduction

According to the National Bridge Inventory latest report (NBI 2013):

More than 600,000 bridge in service across the nation

10% are classified as structurally deficient

14% are classified as functionally obsolete

Maintenance is a growing challenge for federal, state and local governments

Routine bridges suffer from various sources of in-service degradations

Transportation officials are behind their

schedule to keep up with maintenance

It is not feasible to immediately repair all

of the deficient bridges


Introduction

Structural Health Monitoring (SHM) to evaluate system performance

Integration of SHM into practice

Skepticism by transportation agencies

Cost of application relative to the inventory

Potential for large amount of data - DRIP

Manpower and expertise required to interpret the data

5

LevelI (Detection) LevelII (Localization) LevelIII (Assessment) LevelIV (Consequence)

- Qualitative damage

indication

- Structural safety information

- Residual life estimate

- Damage extent

estimation

- Probable damage

location

StructuralHealthMonitoringofBridges

IncreasingComplexity

New technologies to detect damage, monitor the in-situ behavior

Fiber optic sensors

Wireless sensors

Non-contact measurements

Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges – Part I


What is your opinion on the concept of structural health monitoring for

transportation applications?

a. Tool that should be used more often

b. Tool that has limited application in current environment

c. Undecided

Problem Statement

Establish a damage-integrated system performance evaluation framework

Applicable for routine superstructures rather than only high profile bridges

Provide a linkage between design assumption, maintenance, and behavior

Limited to composite steel girder bridges: common in-service structures

Generic approach: extrapolation across other bridge types

“How the field inspection data can be used to

correlate the impact of existing damage scenarios

on the performance of highway bridges?”

Create a mechanism for integrating damage

and deteriorating conditions into a measure

of system performance

6

What transportation agencies are lacking is a fundamental

understanding of the influence of the damage mechanisms

on the system performance


Evaluating bridge system performance

Ideal approaches:

• Full-scale destructive testing of in-service structures with damage

• Laboratory investigation on scaled bridge models

Experimental approach is not feasible

• Associated costs

• Issues with scaling and simulation of actual boundary conditions

Computational modeling provides a suitable alternative

Differential equations

Energy principle

Able to satisfy:

• Equilibrium

• Compatibility

Problem Statement


Mathematical models for structural analysis

Classic analytical models

• Closed-form equations

• More applicable for simple structural components (e.g. beams, simple frames)

• May not be available for complex structural systems

Numerical models

• Assemblage of discrete parts

• Associated with approximate results

• Complexity of model is affected by desirable level of accuracy


8

Common numerical modeling approaches

Grillage method

Finite Strip Method

Finite Element Method



How familiar are you with the finite element method?

a. Not familiar at all

b. Familiar from school, but no experience with application

c. Use this tool on an occasional basis

d. Use this tool regularly

Finite Element Method

Powerful tool common in engineering practices

Commercial FE packages (ANSYS / ABAQUS)


9

Certain challenges must be properly treated to yield accurate results

Modeling of complex structural systems

• Geometrical details

• Load-structure interaction

• Existing damage conditions


Challenges

10

1. Modeling Assumption / Simulation Techniques

Major impact on the accuracy of the results

Element selection

Mesh generation

Loading/boundary conditions

Modeling of the structural details (for steel girder bridges):

Internal reinforcement of concrete slab

Composite action

• Rigid

• Flexible

• Non-composite


Challenges

11

2. Selection of Appropriate Constitutive Material Models

Essential to capture the failure characteristics and ultimate system capacity

Elastic and in-elastic behavior of the material:

Non-homogenous and brittle nature of concrete

Post-yield and strain-hardening of steel

σ

ε

+ tension

- compression

Concrete

σ

ε

+ tension

- compression

Steel

Failure criteria

Cracking/crushing in concrete

Plastic deformations in steel

William – Warnke

Von – Mises


Challenges

12

3. Understanding System-Level Behavior

Inherent structural redundancy due to complex interaction

Simplified in current design and rating practices:

Girder distribution factors (GDF’s)

Load modifiers (redundancy effect)

Ignore system-level behavior and deal with individual components

A true measure of system performance requires fundamental knowledge to

quantify the concept of redundancy in the system.


Challenges

13

4. Damage Modeling / Model Updating

More complexity associated with the model in the presence of damage

Degradation usually causes additional failure mechanisms

Common deteriorations in Highway Bridges

Girder corrosion Section loss Rebar corrosion Delamination

Spalling Settlement Frozen bearing Impact

Majority of previous research focused on element-level behavior

This study aims at integrating damage into the system-level models



What damage or deterioration mechanisms do you consider to be the most

critical for an in-service steel-girder bridge?

a. Corrosion of the deck reinforcement

b. Spalling on the topside or underside of the deck

c. Corrosion of the girders near midspan

d. Corrosion of the girders near supports

Implications of Damage and Deterioration on

the Performance and Serviceability of Girder

Bridges – Part II: Application

Presenting by:

Amir Gheitasi, Ph.D.

Post-doctoral Research Associate

Department of Civil and Environmental Engineering

University of Virginia

MAUTC Webinar – November 2014

Sponsored by:

Mid-Atlantic University Transportation Centers (MAUTC)

Virginia Department of Transportation (VDOT)

Investigation Approach

14 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges – Part II

Model Calibration

15

Phase I: Intact Element-Level Validation

Goal: simulation assumptions, material modeling

Simply-supported steel girder

Experimental Study (1995)

High-strength steel plate girders

Simply-supported boundary condition

Lateral patch loading at mid-span

Corner-supported RC slab

Experimental Study (1999)

Square slab, reinforced in one layer

Supported at four corner points

Loaded at center

Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges – Part II

Model Calibration

16

Phase I: Intact Element-Level Validation (cont.)

Material non-linearity

Non-linear stress-strain relationship

Cracking / crushing (concrete)

Plasticity / strain hardening (steel)

Von-Mises (steel)

William-Warnke (concrete)

Geometric non-linearity (girder)

Out-of-plane flatness of the web

Twisting of the top flange

Non-linear static analysis

Newton-Raphson method


Model Calibration

17

Phase II: Intact System-Level Validation

Goal: understanding system-level behavior, failure characteristics

Single-span Bridge

Laboratory test (1995)

University of Nebraska

Simply-supported boundary condition

Series of patch loadings

4-span continuous bridge

Field test (1971)

State of Tennessee

Supported at the ends and piers

Loaded at third span



Are you familiar with other ultimate capacity and failure bridge tests that

have been published?

Model Calibration

18

Single-span Bridge 4-span continuous bridge

Phase II: Intact System-Level Validation (cont.)

Full composite action was assumed

Monitor load vs. deflection for validation

Punching shear failure mechanism (lab test)

Plastic hinging in girders / crushing in concrete deck (field test)


Model Calibration

19

Phase II: Intact System-Level Validation (cont.)

Classified behavioral stages

Additional system reserve capacity

Single-span Bridge 4-span continuous bridge

Sensitivity study: variation of geometrical and material properties

Evolution of lateral load distribution behavior: inelastic range


Model Calibration

20

Phase III: Damaged Element-Level Validation

Goal: characterizing the impact of damage conditions on bridge components

Selected damage scenarios (common in composite stringer bridges)

Girder corrosion

Usually occurs at either ends

Reduction in thickness, holes

Reduction in load-carrying capacity

• Local buckling

Deck Delamination

Corrosion-induced horizontal cracking

May not cause failure

Major impacts on serviceability

• Premature local crushing


Model Calibration

21

Phase III: Damaged Element-Level Validation (cont.)

Limited experimental data on the system-level behavior with damage

Alternative: validate modeling strategy within element-level domain

Deteriorated steel sub-section

Michigan Tech. University (2005)

W sub-sections

Thickness reduction: web, bot. flange

Delaminated RC slab overlay

UC San Diego (1988)

two-layer slab panels

Lubricated interface


Model Calibration

22

Phase III: Damaged Element-Level Validation (cont.)

Deteriorated steel sub-section

Two FE models: intact & damaged

Global-local buckling failure mode

Capacity reduction due to damage

Delaminated RC slab overlay

Models: monolithic & delaminated

Relative displacement

Capacity reduction due to damage


23

Phase IV: System-Level Damage Integration

Established comprehensive foundation based on the first three phases

Incorporated challenges have been addressed

Last part: evaluation of system behavior with integrated damage

Application to in-service structures

Model Calibration

Integrate Damage Mechanisms into

System-Level Models

Characterize the impact of damage on:

• System Redundancy

• System Ductility

• Operational Safety


24

Phase IV: System-Level Damage Integration (cont.)

Validated model of the bridge system (lab test)

Updated with a series of representative damage mechanisms

Model Calibration


25


Analysis of updated models with deterioration

Model Calibration

Reserve Capacity

(%)


26


State of in-service bridge superstructures in U.S. (NBI 2013)

In Virginia, 50% are stringer, multi girder bridges

32% of stringer are classified as deficient structures

Model Calibration


Parametric Study

27

Selected Structures

Based on Virginia Department of Transportation (VDOT) inventory database

Two in-service bridges in the Commonwealth of Virginia

Represents common geometrical features of in-service structures

Aylett Bridge

Operates on Mattaponi river

King and Queen county, VA

Creek Bridge

Over Piscataway creek

Essex county, VA


Parametric Study

28

Effect of Corrosion in Steel Girders

Damage integration / Model updating

Mesh refinement in damaged areas

Accurate simulation of the damage pattern

Thickness reduction of the elements in the damages regions

Uniform and identical stage of damage among all girders

Aylett Bridge Creek Bridge


Parametric Study

29

Effect of Corrosion in Steel Girders (cont.)

Damage scenarios

Based on a questionnaire submitted to VDOT engineers

Provides min, max, and avg. level of observed deterioration within the state

Variations over shape, depth, and extent level


Parametric Study

30


Flexural and shear loading scenarios

Simply-supported boundary conditions

All sources of material non-linearities were included

Geometric non-linearity was also included

To capture lateral instability of girders in corroded regions

40 cases were analyzed

Linear analysis + hand calculations

• member failure (LF1)

• Member reserve ratio (r1)

Non-linear static analysis

• Ultimate capacity (LFu)

• Functionality (LFf)

• Damaged condition (LFd)


Parametric Study

31


System Safety Assessment

Evaluate the performance of the selected structures

Level of safety ~ system redundancy

Quantitative measure of Redundancy (cont.)

Each limit state must satisfy a target system safety criterion

• Structural reliability analysis

• Several redundant in-service bridges

Use incremental non-linear analysis

• Load factors for each limit state

• Reserve ratios

• Redundancy ratios

• System redundancy factor


Parametric Study

32


Representative results for Aylett Bridge

Damage pattern (shape) has negligible impact on the capacity

Extent level and reduction in thickness dictate the behavior and capacity


Parametric Study

33


Aylett Bridge Creek Bridge

Comparing result from both bridges

Reduction in load-carrying capacity is also affected by:

• Geometry of the structure

• Loading scenario

Redundancy factors

Indicate overall safety

Governed by functionality

Limited to assumptions

• Loading and boundary

• Damage scenarios


Parametric Study

34

Effect of Subsurface Delamination in Concrete Deck

Damage integration / Model updating

Corrosion-induced delamination

Details of damage mechanism and corresponding effects

Modifications over material and geometrical characteristics


Parametric Study

35

Effect of Subsurface Delamination in Concrete Deck (cont.)

Damage scenarios

Aylett bridge was updated with damage cases

Provides min, max, and avg. level of observed deterioration within the state

Based on a questionnaire submitted to VDOT engineers

In all cases, it was assumed that

• Uniform corrosion, top layer

• Upper surface fracture plane

• Uniform crack width: 0.7 mm

• No material degradation for steel

• 30% reduction in concrete

• Ideal case of debonding


Parametric Study

36

Effect of Subsurface Delamination in Concrete Deck (cont.)

Representative results for Aylett Bridge

Flexural loading scenario

Increase in damage area results in more degradation

With the same damage area, scattered patterns would

result in more severe degradation in system performance


Summary

37

The overall objective of this research project was to

Establish a framework to evaluate the in-service condition of bridge superstructures.

Provide a measure of system performance

Characterize the impact of damage on the capacity, redundancy, and safety.

The investigation was limited to composite steel girder bridges

Illustrate a conceptual schematic of a computational modeling strategy

Study the influence of corrosion in steel girders and delamination in concrete decks

Corrosion has major impact on the behavior of the system, with the level of

effectiveness highly depends on the damage extent level.

Delamination has minor impact on non-linear behavior of the system, while it

may reduce the functionality governed by premature failure modes.

The proposed framework could be beneficial to the preservation community

as a mechanism to make decisions based on in-service condition.

It can provide a critical linkage between the design and preservation

communities by correlating the element-level and system-level responses.



Where do you see this study being useful?

a. Application of load rating of existing structures

b. Load testing programs for research purposes

c. Maintenance and preservation decision-making

d. Other – text fill in

Future Research

38

On the basis of the performed investigations, the following future work is

recommended to enhance the knowledge regarding condition assessment:

Study the effect of other damage scenarios (fire, vehicle collision)

Study the impact of coupled damage mechanisms

Evaluate the performance of other types of bridges (corresponding damage)

Integrate sub-structure into the established numerical modeling framework to

include damage scenarios such as scour and flooding, soil-water-structure

interaction, vehicle-structure interaction, and seismic load effects.


Upcoming presentations

• “Implications of Overload Distribution Behavior on Load Rating Practices in Steel

Stringer Bridges” TRB annual meeting, Session 499: Special Topics in Steel

Bridge, January 13, 2015, Washington, DC.

• “Integration of Element Inspection Data in Model Updating and Performance

Evaluation of In-service Bridge Superstructures” SEI structures congress,

Session 2005: Bridge Assessment and Health Monitoring, April 23, 2015,

Portland, Oregon.

Contributions

1. Gheitasi, A., and Harris, D.K. (2015). “Implications of Overload Distribution Behavior on Load Rating

Practices in Steel Stringer Bridges” Transportation Research Board (TRB) 94th Annual meeting,

Washington, D.C.

2. Gheitasi, A., and Harris, D.K. (2015). “Integration of Element Inspection Data in Model Updating and

Performance Evaluation of In-service Bridge Superstructures.” SEI Structures Congress, American Society

of Civil Engineers, Portland, OR.

3. Gheitasi, A., and Harris, D.K. (submitted 2014). “Redundancy and Operational Safety of Composite

Stringer Bridges with Deteriorated Girders.” ASCE, Journal of Performance of Constructed Facilities,

under review.

4. Gheitasi, A., and Harris, D.K. (submitted 2014). “Performance Assessment of Steel-Concrete Composite

Bridges with Subsurface Deck Delamination.” Elsevier, Structures, under review.

5. Gheitasi, A., and Harris, D.K. (2014) “Overload Flexural Distribution Behavior in Composite Steel Girder

Bridges.”ASCE, Journal of Bridge Engineering, 19(8), in press.

6. Gheitasi, A., and Harris, D.K. (2014) “Failure Characteristics and Ultimate Load-Carrying Capacity of

Redundant Composite Steel Girder Bridges: Case Study.“ ASCE, Journal of Bridge Engineering, 19(8), in

press.

7. Gheitasi, A., and Harris, D.K. (2014) “Effect of Deck Deterioration on Overall System Behavior,

Resilience and Remaining Life of Composite Steel Girder Bridges.” SEI Structures Congress, American

Society of Civil Engineers (ASCE), Boston, MA.

8. Gheitasi, A., and Harris, D.K. (2014) “A Performance-Based Framework for Bridge Preservation Based on

Damage-Integrated System-Level Behavior.” Transportation Research Board (TRB) 93rd Annual Meeting,

Washington, D.C.

9. Harris, D.K., and Gheitasi, A. (2013) “Implementation of an Energy-Based Stiffened Plate Formulation for

Lateral Load Distribution Characteristics of Girder-Type Bridges.” Elsevier, Engineering Structures, 54,

168-179.

39 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges – Part II

Thank you for your Attention

Questions?!

[email protected]

[email protected]







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