Real Solutions Presentation 2008 07

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NHI Real Solutions Seminar July 2008

Raymond A. Hartle, P.E.

II--70 Overpass Beam Failure70 Overpass Beam Failure

Lakeview Drive BridgeLakeview Drive Bridge

Washington County, PAWashington County, PA


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Learning OutcomeLearning Outcome

A.A. Assign an NBI rating to aAssign an NBI rating to a

prestressedprestressed, adjacent, adjacentnonnon--compositecomposite box beambox beam

superstructuresuperstructureusing new rating guidelinesusing new rating guidelines


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Rating GuidelinesRating GuidelinesA


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Location MapLocation Map


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Bridge Cross SectionBridge Cross Section

Composite or Non-composite??


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Bridge Plan ViewBridge Plan View


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Forensic Inspection and EvaluationForensic Inspection and Evaluation

ReRe--openingopening

II--70 WB70 WB Safety ofSafety of

otherothersimilarsimilarbridges inbridges in

PAPA


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Forensic Evaluation of MaterialsForensic Evaluation of Materials


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More Evaluation and TestingMore Evaluation and Testing


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Material PropertiesMaterial Properties

Tested concrete and prestressing strandsTested concrete and prestressing strands

met the design criteriamet the design criteria

Design:Design:

59005900 psipsi

Measured:Measured:62006200 psipsi minmin

84008400 psipsi maxmax

Design:Design:

250250 ksiksi

Measured:Measured:276.6276.6 ksiksi

Concrete Strength fc Strand Strength Fy


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Unforeseen Fabrication ProblemsUnforeseen Fabrication Problems

Bottom flangeBottom flangethicknessthickness

Bottom concreteBottom concrete

covercover Wall thicknessWall thickness

Lateral postLateral post--

tensioning tie rodstensioning tie rodsand shear keysand shear keys

Vent holes and drainVent holes and drain

holesholes Prestress LossPrestress Loss


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Correlation of Surface andCorrelation of Surface and

Strand ConditionsStrand Conditions


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Correlation of Surface andCorrelation of Surface and

Strand Conditions (continued)Strand Conditions (continued)

Stirrup

LongitudinalCrack

BottomFlange

Strand


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Key Inspection RequirementsKey Inspection Requirements

1.1. Document exposed strandsDocument exposed strands

2.2. Document cracking patternsDocument cracking patterns3.3. Define strand corrosionDefine strand corrosion

4.4. Measure camberMeasure camber5.5. Investigate Independent Beam ActionInvestigate Independent Beam Action

6.6. Evaluate barrier and barrier connectionEvaluate barrier and barrier connection

7.7. Clear clogged drain holesClear clogged drain holes


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1.1. Document Exposed StrandsDocument Exposed Strands

CollisionCollision

DamageDamageCorrosionCorrosion

DamageDamage


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2.2. Document Cracking PatternsDocument Cracking Patterns

Span 1, Beam 6

Pier 1

Pier 2


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Cracking Near Barrier JointsCracking Near Barrier Joints


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Cracking NearCracking Near

Barrier JointsBarrier Joints


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New 7-Wire Stand

3.3. Define Strand CorrosionDefine Strand Corrosion


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Strand PitchStrand Pitch

77--wire Strand crosswire Strand cross--sectionsection

1 2 3 4 5 6 1

Pitch = 5.2

1 2

435

76


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Corrosion EvaluationCorrosion Evaluation


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4.4. Measure CamberMeasure Camber


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5.5. Investigate IndependentInvestigate Independent

Beam ActionBeam Action


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6.6. Evaluate Barrier and BarrierEvaluate Barrier and Barrier

ConnectionConnection


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7.7. Clear Clogged Drain HolesClear Clogged Drain Holes


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TheThe AftermathAftermath

PennDOTPennDOTs State Owned Adjacent Box Beam Bridgess State Owned Adjacent Box Beam Bridges

As of MayAs of May20062006

BridgeBridgeCountCount

CLOSEDCLOSED LoadLoadPostedPosted

RestrictedRestricted

OverOverHighwaysHighways 2020 33 00 00

OverOver

StreamsStreams 778778 11 1111 1515

Grand TotalsGrand Totals 798798 44 1111 1515


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Prestressed Non-Composite

Adjacent Box Beam Rating


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Looking North Looking South


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NBI RatingNBI Rating

There are delaminations and spallsThere are delaminations and spalls

throughout and several longitudinalthroughout and several longitudinalcracks up to 1/8cracks up to 1/8 wide. Beam 2 haswide. Beam 2 has30%30% of its area spalled or delaminatedof its area spalled or delaminated

and 7 out of 54 (and 7 out of 54 (13%13%) strands) strandsexposed.exposed.

Rating = 3, SeriousRating = 3, Serious


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Rating ReasoningRating Reasoning

SOL 431SOL 431--0606--0303Rating: 4

6-15%

Strands Exposed

(single beam)

Rating: 3

Spalls/Delaminations

>25%


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Learning OutcomeLearning Outcome

A.A. Assign a NBI rating to aAssign a NBI rating to a

prestressedprestressed, adjacent, adjacentnonnon--compositecomposite box beambox beam

superstructuresuperstructureusing new rating guidelinesusing new rating guidelines

II 70 Overpass Beam Failure70 Overpass Beam Failure


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Raymond A. Hartle, P.E.

II--70 Overpass Beam Failure70 Overpass Beam Failure

Lakeview Drive BridgeLakeview Drive Bridge

Washington County, PAWashington County, PA

Thank You!!Thank You!!

Documents

Real Solutions Presentation 2008 07