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

Transcription

1 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)

2 Dr. Harris joined the Civil and Environmental Engineering Department at the University of Virginia in July 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. dharris@virginia.edu 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. agheitasi@virginia.edu

3 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

4 Introduction National Highway system: One of the greatest engineering achievements of the 20 th 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 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 2 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

5 Introduction Tragic failures brought the challenges associated with the safety of the national infrastructure to forefront of the public s scrutiny. I-35, Minnesota (2007) I-5, Washington (2013) M bridge, Missouri (2013) 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 3 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

6 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 4 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

7 Introduction Structural Health Monitoring (SHM) to evaluate system performance Structural Health Monitoring of Bridges Level I (Detection) Level II (Localization) Level III (Assessment) Level IV (Consequence) - Qualitative damage indication - Probable damage location - Damage extent estimation - Structural safety information - Residual life estimate Increasing Complexity New technologies to detect damage, monitor the in-situ behavior Fiber optic sensors Wireless sensors Non-contact measurements 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 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

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

9 Problem Statement What transportation agencies are lacking is a fundamental understanding of the influence of the damage mechanisms on the system performance 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 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 6 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

10 Problem Statement 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 7 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

11 Computational Modeling 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 Common numerical modeling approaches Finite Strip Method Grillage method Finite Element Method 8 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

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

13 Computational Modeling Finite Element Method Powerful tool common in engineering practices Commercial FE packages (ANSYS / ABAQUS) Modeling of complex structural systems Geometrical details Load-structure interaction Existing damage conditions Certain challenges must be properly treated to yield accurate results 9 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

14 Challenges 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 10 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

15 Challenges 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 Steel + tension ε σ - compression Concrete + tension ε Failure criteria Cracking/crushing in concrete Plastic deformations in steel William Warnke - compression Von Mises 11 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

16 Challenges 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. 12 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

17 Challenges 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 13 Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

18 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 I

19 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)

20 Investigation Approach 14

21 Model Calibration 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 15

22 Model Calibration 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 16

23 Model Calibration 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 17

24 Are you familiar with other ultimate capacity and failure bridge tests that have been published? Implications of Damage and Deterioration on the Performance and Serviceability of Girder Bridges Part I

25 Model Calibration 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) Single-span Bridge 4-span continuous bridge 18

26 Model Calibration 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 19

27 Model Calibration 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 Deck Delamination Usually occurs at either ends Corrosion-induced horizontal cracking Reduction in thickness, holes May not cause failure Reduction in load-carrying capacity Major impacts on serviceability Local buckling Premature local crushing 20

28 Model Calibration 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 Delaminated RC slab overlay Michigan Tech. University (2005) UC San Diego (1988) W sub-sections two-layer slab panels Thickness reduction: web, bot. flange Lubricated interface 21

29 Model Calibration 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 22

30 Model Calibration 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 Integrate Damage Mechanisms into System-Level Models Characterize the impact of damage on: System Redundancy System Ductility Operational Safety 23

31 Model Calibration Phase IV: System-Level Damage Integration (cont.) Validated model of the bridge system (lab test) Updated with a series of representative damage mechanisms 24

32 Model Calibration Phase IV: System-Level Damage Integration (cont.) Analysis of updated models with deterioration Reserve Capacity (%) 25

33 Model Calibration Phase IV: System-Level Damage Integration (cont.) 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 26

34 Parametric Study 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 27

35 Parametric Study 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 28

36 Parametric Study 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 29

37 Parametric Study Effect of Corrosion in Steel Girders (cont.) 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 (LF 1 ) Member reserve ratio (r 1 ) Non-linear static analysis Ultimate capacity (LF u ) Functionality (LF f ) Damaged condition (LF d ) 30

38 Parametric Study Effect of Corrosion in Steel Girders (cont.) 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 31

39 Parametric Study Effect of Corrosion in Steel Girders (cont.) 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 32

40 Parametric Study Effect of Corrosion in Steel Girders (cont.) 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 33

41 Parametric Study 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 34

42 Parametric Study 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 35

43 Parametric Study 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 36

44 Summary 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. 37

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

46 Future Research 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. 38

47 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,

48 Thank you for your Attention Questions?!