9/7/2010 SHM General Concepts Project Concept Techniques Remote Sensing In-Progress Structural Health Monitoring Remote Sensing Technologies for Detecting Bridge Deterioration and Condition Assessment • Ensuring structural integrity and safety g g y y • Static/dynamic field testing Tess Ahlborn, Ph.D., P.E. • Periodic and continuous monitoring with Devin Harris, Colin Brooks, Arthur Endsley, • Routine and special inspections Darrin Evans, Renee Oats, Khatereh Vaghefi, Larry Sutter, Bob Shuchman, Joe Burns, and Chris Roussi • Data management / interpretation Data management / interpretation Michigan Technological University Michigan Technological University Mi hi Mi hi T T h h l l i i l U i l U i it it • Decision support August 18, 2010 NDT/NDE for Highway Bridges – SMT 2010 2 SHM General Concepts SHM General Concepts Project Concept Techniques Project Concept Techniques Remote Sensing Remote Sensing In-Progress In-Progress MECHANICAL DURABILITY BRIDGE TYPE (Global Structural Integrity) (Local Material Integrity) ‐ Slab ‐ Girder Deflection Cracking Strain Corrosion ‐ Displacement Transducers ‐ Visual Inspection ‐ Box ‐ Beam ‐ Electrical Resistance Gages ‐‐ Tiltmeters (rotation) ( ) ‐ Acoustic Emission ‐ Half ‐ cell Potential ‐ Arch Arch ‐ Fiber ‐ Optic Gages Fib O ti G ‐ Seismic (accelerometers) ‐ Ultrasonic Pulse Velocity ‐ Acoustic Emission ‐ Cable ‐ Stayed ‐ Vibrating Wire Gages ‐ Thermography ‐ Laser MATERIAL (SUPERSTRUCTURE) ENVIRONMENTAL CONDITIONS ‐ Concrete Thickness Stiffness Delamination Thickness (Cover) ‐ Freeze ‐ Thaw ‐ Caliper ‐ Seismic (accelerometers) ‐ Chain Drag ‐ Ground Penetrating Radar ‐ Steel ‐ Environmental Loads ‐ Ground Penetrating Radar ‐ Displacement Transducers ‐ Imact Echo ‐ Impact Echo ‐ Timber Bridge Condition ‐ Chemical Attack ‐ Composite Assessment LOADING/BOUNDARY CONDITIONS GEOMETRY ‐ Simple ‐ Span ‐ Continuous ‐ Width ‐ AASHTO Notional Loading ‐ Skew/Curvature ‐ State Specified Loading ‐ Girder Spacing ‐ Overloads/Special Loading ‐ Deck Thickness 3 4 1
9/7/2010 SHM General Concepts SHM Priorities Project Concept Techniques Project Concept Goals Remote Sensing Remote Sensing Concept In-Progress In-Progress Structural Health Monitoring Top 10 Priorities / Challenges Scour/Settlement – The group agreed • • Decks ‐ delamination /spalling, one • Traditional Inspection Techniques that scour is a project within itself and of the largest influences on public beyond the scope of this project. beyond the scope of this project perceptions of road condition. i f d di i – Visual, chain drag, half ‐ cell potential, accelerometers However, settlement is something that • Decks – map cracking and other should be considered. • Advanced Monitoring Techniques material related distresses. • Corrosion damage of prestressed • Expansion joint failure – expansion concrete beams is a serious concern, – GPR, impact echo, fiber optics, thermal IR, ultrasonic joint damage can be an indicator of especially with end deterioration, water and other damage that can – Wireless remote monitoring section loss, and strand damage. lead to further problems. • Steel beam section loss is also a • Chloride ingress – if DOTs had a • Remote Sensing: Non contact data collection • Remote Sensing: Non ‐ contact data collection serious concern often most serious at serious concern, often most serious at better way of estimating the better way of estimating the the end of the beams and base of chloride level, deck replacements – “ the collection of data about an object, area, or columns. would be scheduled differently. • Vibration can be an indication of other • Length of bridge – the typical bridge phenomenon from a distance with a device that is not concerns with the bridge. shortens over time ‐ a location item in contact with the object. ” • Large cracking is an indication of and length change concern. structural damage. 5 6 = − X ln( L L ) SHM Priorities SHM Priorities i i si Project Concept Goals Project Concept Goals Remote Sensing Concept Remote Sensing Concept In-Progress In-Progress Project Goals USDOT Project Concept – Establish remotely sensed bridge condition “signature” Bridge Management System Data ( ) e j 2 kR ( ) ≈ ∫ ρ ′ − ⋅ ′ ′ s k , r r e j 2 k ˆ r r d r π Structural Health Monitoring Model 4 R Maintenance Records • Assess the potential for commercial remote sensors to be used to assess Assess the potential for commercial remote sensors to be used to assess Period 0 Period 0 Meteorological Data Meteorological Data bridge condition and performance (Baseline) Transportation officials utilize dynamic DSS Bridge Health Signature to evaluate changing condition • No lane closures, no traffic disruption, no contact with bridge Bridge Health DSS: algorithms & interface Decision Support System Indicators Periodic assessments enhanced with – Provide bridge inspectors with data to enhance Period 1 remote sensing as trouble spots are TIME identified inspection processes • Provide condition monitoring between required inspections Trouble Spot 1 Trouble Spot 2 BRIDGE – Create the framework for a decision support system to Create the framework for a decision support system to BRIDGE MANAGEMENT TEAM Period X Data Collection prioritize needs (Current) Bridge Health Signature Damage Location On Site and In Situ Sensors • Correlate on ‐ site , in ‐ situ , and stand ‐ off sensors with conventional assessment methods, historic bridge information, and bridge standards Relay and requirements 7 8 2
9/7/2010 SHM SHM Project Concept Project Concept Remote Sensing Remote Sensing In-Progress In-Progress Electro ‐ Optical Imagery Speckle Photography and Speckle Pattern Interferometry satellite platform Definition : Speckle patterns are high ‐ contrast, fine ‐ scale, granular Definition : Any digital Definition : Any digital patterns produced by light reflected from optically rough surfaces. photography in the optical, Proposed Application : Interferometry of speckle patterns produces thermal infrared, and near fringes from which deformations or displacement gradients infrared parts of the spectrum (strain) can be inferred. collected from an aerial, satellite, or other platform Speckle pattern of Speckle pattern of Difference of the two undeformed surface deformed surface speckle patterns Proposed Application : Mapping Proposed Application : Mapping bridge features; 3D models; characterizing deck surface (spalling, cracks) 9 10 SHM SHM Project Concept Project Concept Remote Sensing Remote Sensing In-Progress In-Progress Synthetic Aperture Radar (SAR) and Interferometric SAR (InSAR) Synthetic Aperture Radar (SAR) and Interferometric SAR (InSAR) Definition: SAR collection uses multiple radar (electromagnetic [radio] Definition: SAR collection uses multiple radar (electromagnetic [radio] wave reflections) returns from small(er) antennae to simulate one wave reflections) returns from small(er) antennae to simulate one wave reflections) returns from small(er) antennae to simulate one wave reflections) returns from small(er) antennae to simulate one radar measurement from a single, large antenna; increases effective radar measurement from a single, large antenna; increases effective resolution . resolution . Proposed Application: Bridge dynamics, vibration, and strain; bridge Proposed Application: Bridge dynamics, vibration, and strain; bridge stiffness; bridge settlement stiffness; bridge settlement Example of InSAR used for InSAR elevation data InSAR elevation data infrastructure mapping 11 12 3
9/7/2010 SHM SHM Project Concept Project Concept Remote Sensing Remote Sensing In-Progress In-Progress Digital elevation model Ground ‐ Penetrating Radar (GPR) LiDAR / Laser Scanning Definition: Depth sounding by radio waves emitted over a wide Definition: 3D mapping (scanning) of frequency band either continuously or in discrete pulses as an f b d ith ti l i di t l surfaces or objects by timing the f bj t b ti i th antenna sweeps the ground. reflection of millions of laser pulses. Proposed Application: Characterization of deck subsurface; Proposed Application: 3D modeling; detection of delaminations, voids, etc. detecting bridge displacement; measuring size and shape of features Infrastructure mapping pp g 13 14 SHM SHM Project Concept Project Concept Remote Sensing Remote Sensing In-Progress In-Progress GPS/Geodetic Measurement GPS/Geodetic Measurement Definition: Use of precision measurements of position to Definition: Use of precision measurements of position to determine movement over time determine movement over time determine movement over time determine movement over time From Roberts (2005): Lateral bridge Proposed Application: Absolute displacement Proposed Application: Absolute displacement movement detected by GPS measurements of structural elements; measuring measurements of structural elements; measuring bridge length bridge length 15 16 4
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