fib Bulletin 33 and FHWA Scan tour Findings - Post … Convention/Session... · fib Bulletin 33 and...

Durability of Post-Tensioning:

fib Bulletin 33 and

FHWA Scan tour Findings

Presented by Brett Pielstick P.E., F.ASCE

1

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Introduction

Early Durability Issues

Assessment

Concrete Society TR-47

FHWA Scan Tour

fib Bulletin 33

Florida Strategies

Conclusions

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

FHWA Scan Tour

EU Performance Seg’l and Cable Stay

European average 10 years older than US

First segmental bridges - from 1960’s

First modern cable-stay - c. 1962 (Swiss)

Overall performance is good - Europeans are

well satisfied and continue to build them

“Old-issues” c. 1970’s (e.g. excess creep

deflection, etc.) solved by standards and

practice introduced in 1975. All now O.K.


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Rehab of 1st Generation –(pre 1970’s)

Chillon Viaduct (Switzerland)

Added PT to cantilevers with mid-span hinges

No corrosion - good waterproofing / overlay

Autobahn Bridges (various - Germany)

Cracks at 1/4 span joints with coupled

tendons

Add external grease and sheath mono-strand

Corbeil Bridge (France)

Added external longit PT to midspan - with

Transverse PT to bottom slab / internal frames


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Chillon Viaduct, Switzerland, built 1967

Continuous

Midspan

hinges

Deflection

External PT

added

Waterproof

deck - no

corrosion of

tendons


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Rehab. of “Coupling Joint” - Koln, 1999


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY


Corbeil Bridge Rehabilitation

France

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Internal Transverse Frames


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Failures of pc-bridges in Europe due to corrosion

of the pt-tendons:

• 1967: 2 pedestrian bridges (UK)

• 1985: Ynis-y-Gwas Bridge (UK)

• 1992: Bridge over the Melle River (B)

• 1999: San Stefano Bridge (I)


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

San Stefano Bridge (I):


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

What are the problems?

Voids

Bleed water

Recharge water

Failure due to corrosion

Material Deficiencies

Poor Design Details

Poor Construction Practices

Assessment US Experience

EU Experience

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

EU Maintenance Policy

All EU countries perform regular inspections or

condition checks

Generally, pro-active repair is implemented as

soon as any damage found

Bridge Management Systems vary according to

country, resources and needs but most are

similar to those in the US

Maintenance funds may meet “half” of need

(compare to US where only 10 to 20%)

Assessment

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Non-Destructive Evaluation (NDE)

EU and US methods for old tendons and

stays:

gammagraphy

x-ray

ultra-sonic

georadar

magnetic perturbation

electrical resistance… etc

all only partially useful = no “magic bullet”

Assessment

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

CONCRETE SOCIETY TR 47

Durable post-tensioned concrete bridges

Holistic approach, covering:-

• Materials

• Design

• Detailing

• Construction quality

Concept of multi-layer protection

• to the tendons

• to the structural elements

• to the bridge as a whole

Scope

• All bridges in all environments, without pre-

knowledge of design details or construction quality

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Exposed Anchorage

DESIGN DETAILS

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Expansion Joint

DESIGN DETAILS

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Buried Anchorage

DESIGN DETAILS

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Recommendation prepared by

Task Group 5.4:

Jean Philippe Fuzier

Peter Matt

Hans Rudolf Ganz

fib Bulletin 33:

Durability of post-tensioning tendons

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

fib Bulletin 33:


1. Design concepts for durable post-tensioning

tendons

2. Materials and construction

3. Maintenance, assessment and rehabilitation

References

Appendix: Maintenance, assessment and

rehabilitation of post-tensioning

tendons in existing structures

Appendix references

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Hazard scenarios for prestressing steel in a

typical box girder bridge

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Protection levels for post-tensioning tendons

PL2

PL3

PL1

Structural protection layers

[Protection provided by structure]

High Medium Low

Aggressivity

or

Exposure

High

Medium

Low

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Aggressivity of the environment and exposure

examples: Based on EN 206-1 classes

Aggressivity level: Class [Description of environment]

[Informative examples where exposure classes may occur]

1 – No risk of corrosion or attack Low: X0

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY






2 – Corrosion induced by carbonation Low: XC1, Medium: XC4

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY







3 – Corrosion induced by chlorides other than from sea water Medium: XD1, High: XD3

4 – Corrosion induced by chlorides from sea water

Medium: XS1, High: XS3

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY







3 – Corrosion induced by chlorides other than from sea water Medium: XD1, High: XD3

4 – Corrosion induced by chlorides from sea water

Medium: XS1, High: XS3

5 – Freeze / thaw attack with or without de-icing agents Moderate saturation High saturation

Medium: XF1 Medium: XF3 [No de-icing agent]

High: XF2 High: XF4 [With de-icing agent]

6 – Chemical attack Medium: XA1, High: XA3

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Agressivity level and exposure


Aggressivity

level Class Description of

environment

Informative examples where exposure

classes may occur

1 – No risk of corrosion or attack

Low X0 For concrete without

reinforcement or embedded

metal: all exposures except

where there is freeze/thaw,

abrasion or chemical

attack.

For concrete with

reinforcement or embedded

metal: very dry.

Concrete inside buildings with very low air

humidity

2 – Corrosion induced by carbonation

Low XC1 Dry or permanently wet Concrete inside buildings with very low air

humidity

Concrete permanently submerged in water

XC2 Wet, rarely dry Concrete surfaces subject to long-term water

contact

Many foundations

XC3 Moderate humidity Concrete inside buildings with moderate or high

air humidity

External concrete sheltered from rain

Medium XC4 Cyclic wet and dry Concrete surfaces subject to water contact, not

within exposure class XC2

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Protection provided by the structure

Recognizes concept of multi-layer protection and related influences:

Concrete quality and cover 1.3.3

Waterproofing / surface protection systems 1.3.4

Drainage system 1.3.5

Expansion joints 1.3.6

Cracking 1.3.7

Construction joints 1.3.8

Segment joints 1.3.9

Tendon layout 1.3.10

Access for inspection & maintenance 1.3.11

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Protection provided by the structure

Recognizes concept of multi-layer

protection and related influences.

Further considerations are:

the quality of construction: contractor qualification,

specific competence, workmanship certification

products availability, quality of materials

inspection and maintenance program

possibility of tendon replacement

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Tendon system for Protection level 1

PL1

Anchor head

Prestressing steel

Anchorage

Cement grout

60mm

Temporary protection cap

Sheet metal duct

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY


PL2

Permanent protection cap

Anchor head

Prestressing steel Plastic duct

Cement grout

Anchorage 60mm

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY


PL3

the resistance measurement

Isolating insert

Anchorage Electrical connection for

Prestressing steel

Isolating protection cap

Anchor head

Plastic duct

Cement grout

60mm

For unbonded tendons, the cement grout is replaced by grease in the

above systems, and there should be a permanent cap for all systems.

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Bulletin 33: Further considerations

For the finished works to be durable it is

necessary:

To make reference international QA & QC standards

For good design practice to be matched with good

construction practice.

For expertise and craftsmanship to be recognised &

required in project specifications in order to assure

that best practices are followed.

That protection Levels (PL) should be established by

performance testing rather than by prescriptive

solutions.

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Instrument for measuring

the electrical resistance of

tendons (PL3)

End caps and electrical

junction box for monitoring

of electrically isolated

tendons (PL3)

fib Bulletin 33:


PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Bulletin 33: Construction Details

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Contents

• Precast Balanced

Cantilever

• Precast Span-by-Span

• Spliced I-Girders

• CIP Balanced Cantilever

• CIP on Falsework

• Substructures

• Transverse Superstructure

• Condition Inspection &

Maint.

• Load Rating

• Concrete Segmental

• Concrete Beam

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Objective

To Provide Consistency and Uniformity in the

Design, Detailing, and Construction of Post-

Tensioned Structures in Order to Provide a

Higher Quality Product with a Minimum Cost

Increase

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

More Specifically, to Improve the Quality of

PT Hardware, Grouting, and Anchor

Protection in Order to Reduce the

Incidences of Recharge and Corrosion in

Post-Tensioned Structures

Objective

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Post-Tensioning Strategies

Anchor Protection

Fully Grouted Tendons Multiple Tendons Paths

Enhanced PT Systems

Watertight Bridges

FDOT PT

Strategy

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Requirements

• 4 Levels of Protection

• Semi Standard Details

• Anchorages Sealed at all Times

Requirements

• Anchorage Accessibility

• Low Point Injection

• Semi-Standard Drawings

• Certified Grouters and Inspectors

• Controlled Rates of Grouting

• Flow Rate Testing of Ejected Material

• Inspect Voids and Secondary Grout

Requirements

• Pre-Approved PT Systems

• Pre-Bagged Grout

• Three-Level Continuous Protection

• Plastic Ducts with Improved Cell Class

• Positively Sealed Ducts

• Permanent Plastic Anchor Caps

• Pressure Testing

Requirements

• No Dry Joints

• Pre-formed Tapered Holes

• Drip Notches at Anchorages

• Bottom Slab Drains

• Sealed Surfaces of Secondary Pours

• Wearing Surfaces for Ride not Protection

• No Permanent Tensile Stresses

Flo

rida

PT

Str

ateg

y

Enhanced PT Systems

Fully Grouted Tendons

Watertight Bridges

Anchor Protection

Requirements

• Maximize Use of Smaller Tendons

• No Impact Due to Loss of Critical Tendon

• Compensation for Loss Due to Corrosion

Multiple Tendon Paths

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Strategy 1 Enhanced Post-Tensioning Systems

Sealing Of Grout Ports, Vents and Drains

Strategy 2 Fully Grouted Tendons

Accessible Anchors

Grouting of Tendons / General Procedures

Florida Strategies

Objective

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Objective

Strategy 3 Multi-Level Anchor Protection

Anchors at Expansion Joints / Inside

Boxes / Blisters

Embedded Anchors

Strategy 4 Watertight Bridges: Double Face Epoxy

Access, Lifting Holes

Drip Notches

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Strategy 5 Multiple Tendon Paths

Maximize Use of Smaller Tendons Design

for Tendon Loss

Compensation for Loss Due to Corrosion

Florida Strategies

Objective

Balanced Cantilever Construction

Florida Strategies

• Type of Construction CIP on Falsework

CIP Balanced Cantilever

P/C Balanced Cantilever

P/C Span-By-Span

P/C Beam w/ CIP Slab

• Structural Purpose Superstructure

Substructure

Construction vs. Permanent

Bonded vs. Unbonded

• Tendon Protection System Mat’ls – Duct, Anchor, Grout

Wet vs. Dry Joints

Risk of Exposure

• Maintainability Access to Inspect Components

Applicability of Test Methods

Ability to be Replaced

• Redundancy External

# & Distribution of Tendons

Critical Nature of Tendons

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Drawing Indices

Instructional Notes

Post-Tensioning Vertical Profiles

Post-Tensioning Anchorage Protection

Post-Tensioning Anchorage and Grouting

Details

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Instructional Notes

Designer to Provide Tendon Profile and

Anchor Protection Type for Each Type of

Tendon

Tendon Profile and Anchor Protection Type

to be Included in the PT Schedule

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Instructional Notes

Tendon Profiles may be Amended by the

Engineer

EOR Responsible for Reviewing the

Contractors Grouting Plan (Shop Drawings)

Deviations from the Standards shall be

Approved by the FDOT

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Reminder Details are Great

but one Must Always…

INTEGRATE STRATEGIES INTO THE

CONSTRUCTION AND

MATERIALS SPECIFICATIONS

“One gets what he INSPECTS not what

he EXPECTS”

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Post-Tensioning System

example items

Inspectable Anchors

Bar Couplers

Permanent Grout Caps

Inlets and Outlets

Duct Schedule 40 Steel or Plastic

Polypropylene Corrugated Duct

Polyethylene Smooth Duct (Dr 17)

Pressure Testing Components with System

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Plastic Duct And Connections

example issues

All Components Assembled into Pressure Tested Systems

Polypropylene Corrugated Duct for Internal Tendons Greater Stiffness with Less Heat Gain

Polyethylene Duct Thick Wall with Pressure Pipe Chemistry

In-place Testing for Leaks Before Grouting

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Where is Florida Now ?

Revisiting Galvanized Ducts for Beam Bridges

Evaluating Pressure Testing of Systems in Field

Utilizing New DSI Coupler System on I-95/I-295

North Flyover, Jacksonville, Florida

Florida Strategies

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

FHWA European Scan -

Conclusions

In general, segmental and cable-stay

bridges in Europe are performing well

They comprise important technology and

are still being designed and built.

The Scan found no new dramatic

revelations

In general, US and EU head in same

direction - thus confirming current

practice

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Garcon Point, Oriole Beach, Florida

Ernest Lyons, Stuart, Florida 17st Causeway, Ft Lauderdale, Florida

Memorial Causeway, Clearwater, Florida Hathaway Bridge, Panama City, Florida

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Sallingsund, Denmark (opened 1979)

Sunnibergbrucke - Switzerland

M180, Trent Bridge, UK, (opened 1979)

Chillon Viaduct, Switzerland, built 1967

PO

ST

-TE

NS

ION

ING

DU

RA

BIL

ITY

Proper Procedure & Inspection

will Yield Enduring Results

Acosta Bridge Jacksonville, Florida

Seabreeze Bridge Daytona Beach, Florida

Broadway Bridge Daytona Beach, Florida

fib Bulletin 33 and FHWA Scan tour Findings - Post … Convention/Session... · fib Bulletin 33 and...

Documents

Transcript of fib Bulletin 33 and FHWA Scan tour Findings - Post … Convention/Session... · fib Bulletin 33 and...