M. McKenzie Guidelines on the selection of
innovative techniques for the rehabilitation of
concrete highway structures 3
A. Žnidaric Optimised assessment of bridges 31
E. Denarié Ultra High Performance Fibre
Reinforced Concretes (UHPFRC) for rehabilitation
1. Motivation and Background 69
M. Richardson Guidance on use of surface-applied
corrosion inhibitors Context and Framework of
Guidance 97
A. Žnidaric Optimised assessment of
bridges Case study 1 - Medno bridge - Soft Load
Testing 135
A. OConnor Optimised assessment of bridges
Case study 2 Danish examples 149
JC. Putallaz Ultra High Performance Fibre
Reinforced Composites (UHPFRC) for
rehabilitation - 2. Case study first
application 165
M. Richardson Guidance on use of surface-applied
corrosion inhibitors Workshop on detailed
guidance and Case Studies 197
E. Brühwiler Advances in rehabilitation of
highway structures Discussion, Summary and
Perspectives 233

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4
Guidelines on the selection of innovative
techniques for the rehabilitation of concrete
highway structures

Malcolm McKenzie
TRL Ltd, UK

5
Development Team

Richard Woodward, TRL Ltd
Team
Ales Žnidaric ZAG
Mark Richardson UCD
Emmanuel Denarié EPFL
Tomasz Wierzbicki IBDIM
Alan OConnor TCD
Professor Joan Casas UPC
Ciaran McNally UCD
Malcolm McKenzie TRL
Bill McMahon TRL

6
Overview

Guidelines and innovation
Deteriorating concrete structures
Selecting the best rehabilitation option for a
structure
Special procedures for innovative techniques
Ranking projects when budgets are limited
GUIDELINES NOT RULES

7
Guidelines and innovation

Innovation is an essential part of engineering
development
Materials and techniques are always being
improved
There are acknowledged problems with existing
rehabilitation techniques
Cautious approach aimed at controlling risks and
developing experience
Yesterdays innovation is todays tradition

8
Concrete bridge deterioration
9
Some deterioration mechanisms

Reinforcement corrosion
Alkali silica reaction
Freeze/thaw effects
Sulfate attack
Cracking (settlement, thermal)
Overloading
Impact damage

10
Identification of problem

Cause
Extent
Importance
based on
Inspection
Structural Assessment

11
MAINTENANCE OPTIONS

Do nothing
Monitor further deterioration
Carry out remedial treatment
Carry out strengthening
Replace element or structure

12
Procedure
13
Innovative techniques additional risk

Lack of a long established track record
Uncertainties in
Conditions under which they will be effective
Side effects
Long term durability
Implications for future maintenance
Monitoring effectiveness

14
Balance conflicting Issues

Technical aspects need to be considered along
with other relevant factors to meet the needs of
current and future customers.

COST
TIME
ENVIRONMENT
15
Wallet
Cost of repairs
Impact on local economy
Running costs
Cost of delays
Renewal costs
Affordability
16
Watch
Time of works
User delays
When
Life of repair
17
World
Aesthetics
Raw materials
User delays
Transport of materials
Energy usage
Noise
Pollution
18

Decision making - WWW

Rigorous
Engineering Judgement

19
Rigorous approach

Methodology
Convert everything to financial value
Minimise cost over life of structure
Problems
Conversion to money
Lack of data
Not practicable

20
Engineering Judgement

Advantages
Simple to use
Allows engineer to take all factors into
consideration
Problems
Subjective
Decisions could vary

21
Structured Engineering Judgement

Formalise the decision making process
Justification of decisions at each stage
Best option for a structure
Rank individual projects
Independent review
eg via a Workshop

22
Decision criteria

Define objectives of the rehabilitation
Define factors to be considered
Define decision criteria
Basis of comparison eg whole life cost
Relative importance of each factor
Subjective or numerical approach

23
Select rehabilitation options

Identify potential options
Implications of using an innovative technique
Assessment of options in relation to decision
criteria
taking account of any additional actions
resulting from innovative procedure
Recommend option(s)

24
Assessing innovative techniques

Desk study of structure and environmental
conditions relevant to technique
Laboratory testing
Feasibility trials
Cost/time implications

25
Select technique - 1

Example Reinforcement corrosion
Early Stages
Few visible defects
Low levels of chloride
Half-cell potentials mainly passive
Low corrosion currents
Preventative maintenance
Slow down chloride ingress eg surface treatment
Corrosion inhibitors to prevent corrosion?

26
Select technique - 2

Example Reinforced concrete
Visible defects
Higher chloride levels
More negative half cell potentials
Higher corrosion currents
Concrete repairs
Electrochemical techniques
Corrosion inhibitors to reduce corrosion rates??

27
Prioritise competing projects

Risk associated with not carrying out maintenance
What is the consequence of this occurring?
Safety
Functionality
Sustainability
Environment
What is the likelihood of this occurring?

28
Prioritisation Scoring

This comprises three parts
Risks averted
Added value
Timing
All ranked on a numerical basis

29
Procedure
Inspection Assessment
Identify need
Options Available
Select rank rehabilitation option
Decision
Is option innovative
N
Apply Technique
Innovative techniques
Y
User Experience
Control risks
30
Guidelines and innovation

It is wise to be cautious in the use of
innovative techniques
It is foolish to be over-cautious
Engineers need to take controlled risks to grow
confidence in new techniques
Todays innovation is tomorrows tradition

31
THANK YOU FOR YOUR ATTENTION
32
Optimised assessment of bridges

Aleš Žnidaric
Slovenian National Building and Civil
Engineering Institute

33
Contents

General about bridge assessment
Load testing
Traffic loading
Static
Dynamic
Conclusions

34
Why optimised assessment?
35
Design vs. assessment

new bridges are designed conservatively
uncertainty about increased loading
inexpensive to add capacity
assessment should be less conservative
expensive to strengthen/replace or post a bridge
capacity and loading can be measured/monitored

36
Design vs. Assessment

New bridges
high uncertainties
conservative capacity
design loading schemes
design methods
?
high safety factors
unnecessary
costly rehabilitation
load limits

Existing bridges
better defined inputs
realistic capacity
realistic loading
assessment methods
?
lower safety factors
savings
cheaper rehabilitation
posting of bridges

37
Why optimised assessment?

to select optimal rehabilitation measures
do nothing
protect
repair
strengthen
replace

38
Assessment of existing bridges

Important factors
condition, level of damage
structural safety
carrying capacity
loading (dead, traffic, dynamic loading)
reliability of data
serviceability (clearances, traffic,
obsoleteness)
service life, importance

What is the carrying capacity?
age, condition, drawings
What is the real behaviour?
influence lines
load distributions
What is the real loading?
in a country, type of road, on specific bridge
dynamic amplification

5-level assessment
39
Condition assessment

Objectives
Detect possible deterioration processes
Indication of the condition of
structure
its elements
highway structure stock
Ranking the structures
Optimisation of budget allocation

40
Condition assessment

Influencing factors affecting deterioration
Design stage
Detailing
Durability
Materials
Construction stage
Loadings
Maintenance

41
Condition assessment

D19. Report on assessment of structures in
selected countries
condition rating
Cumulative
Highest value
4 factors
Type of damage and its affect on the safety,
serviceability and/or durability
Maximum intensity
Influence of the affected structural member on
safety, serviceability and durability of the
whole structure or its component
Extent and expected propagation

42
Condition assessment

Handbook of damages
http//defects.zag.si/
10 types of damages
descriptions
affected bridge component
influencing factor design, material,
construction, overloading, environment and
maintenance
specific influencing factor
additional data or explanations
photos
Living application

43
Safety assessment

to verify that a structure has adequate capacity
to safely carry or resist specific loading
levels
RgtS
Load testing
Live load assessment (static and dynamic)
How to relate condition and capacity?

44
Load testing

on bridges that seem to carry out normal traffic
satisfactorily, but fail to pass the assessment
calculation
the available model of the bridge does not
perfectly match with the real bridge itself
to supplement and check the assumptions and
simplifications made in the theoretical
assessment
To optimise bridge assessment by finding reserves
in load carrying capacity

45
Load testing

benefits
less severe rehabilitation measures
less traffic delays
tremendous savings

drawbacks
very costly
danger of damaging the structure

best candidates
difficult structural modelling
lack of documentation (drawings, calculations,)
when savings are greater than the cost of load
test

46
Load testing

Types of load test
proof
diagnostic
soft

47
Soft load testing - advantages

the lowest level of load application
uses bridge WIM to provide
normal traffic data
information about structural behaviour of the
bridge
influence lines
statistical load distribution
impact factors from normal traffic.
quickcheap
no need for pre-weighed vehicles
no need to close the traffic
no risk of overloading and damaging of the
structure

48
BWIM shema
49
Soft load testing

Theoretical vs. measured influence line

50
Soft load testing limitations

not intended to predict the ultimate state
behaviour
validity of bridge assessment is often short-term
and depends on the level of safety
if higher traffic loading is expected,
measurements should be extended or replaced by a
normal diagnostic load test
the soft load testing procedure has only been
tested and used on bridges shorter than 40 m
requires an experienced engineer who can
realistically evaluate situation

51
Traffic load modelling

calibrated notional load models (loading schemes)
for
design
assessment (rating loading schemes)
site specific modelling based on traffic data
Monte Carlo simulation
simplified models (convolution)

52
Truck histograms from Europe
53
Truck histograms from Europe

There is an urgent need for effective overload
enforcement better compliance with legal limits
will greatly reduce traffic loading on bridges.

54
Comparison of sites in NL and SI
55
Dynamic Amplification Factor

problem combining the extremes of dead load and
dynamic effects gt very high DAF
options
codes conservative
modelling time-consuming and difficult due to
many unknowns
measurements promising, but only possible since
recent development of bridge WIM systems

56
Dynamic Amplification Factor

Case Study
Calculating dynamic amplification for 1000-year
extreme loading event
Mura River Bridge, Slovenia
2 lanes, opposing directions
extensive Monte Carlo static load simulation 10
years
identified 100 max-per-month static loading
events

57
Dynamic Amplification Factor

Case Study
FE model of bridge and 5-axle articulated
vehicles
Calibrated by site measurement
Considered edge beam
Found total effect for each max-per-month event

58
Dynamic Amplification Factor

Case Study
Max-per-month Data of static vs. total
Fit to bivariate extreme value distribution
Extrapolated the trend to the 1000-year
situation
Dynamics was very small less than 6

59
Dynamic Amplification Factor

SAMARIS experiment
31-m long span
to assess influence of pavement unevenness
to evaluate DAF for 1000s of vehicles
upgraded SiWIM system

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61
Dynamic Amplification Factor
62
Dynamic Amplification Factor
63
Dynamic Amplification Factor

Before resurfacing

64
Dynamic Amplification Factor

After resurfacing

65
Dynamic Amplification Factor

Average value

Coefficient of variation

66
Conclusions (1/2)

Design conservatively, assess optimally
Proper assessment (with monitoring) can
prove that many existing bridges are safe in
their current condition for their current
loading
? factors from Eurocodes are too high for
assessment of existing bridges
traffic patterns in EU, EEA and CEC are different
carrying capacity is higher than expected
justify optimal rehabilitation measures
save a lot of money

67
Conclusions (2/2)

soft load testing is proposed as a simpler way of
defining real bridge behaviour
dynamic amplification factors for the extreme
load cases are considerably lower than specified
in the design codes
additional topics in the D30
factors required for efficient bridge inspection
specifications for diagnostic load test
several case studies

68
Acknowledgment

WP 15 team
ZAG Ljubljana Igor Lavric, Jan Kalin
UCD Dublin Prof. Eugene OBrien, Colin Caprani,
Gavin OConnell, Abraham Getachew
TCD Dublin (now Rambøll) Alan OConnor
UPC Barcelona Prof. Joan Casas
IBDiM Warsaw Tomasz Wierzbicki

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70
Ultra High Performance Fibre Reinforced Concretes
(UHPFRC) for rehabilitation 1. Motivation and
Background

Emmanuel Denarié
Laboratory for Maintenance and Safety of
Structures (MCS)

71
OUTLINE

Introduction
UHPFRC materials
What is proposed?
Why?
Validation
Conclusions
Acknowledgements

72
1. Introduction
? Road networks variety of structures, with a
variety of sizes, geometries, local conditions,
and common weak zones
73
? Exposures to environmental loads
? Most severe contact with liquid water - XD2,
XD3, XA2,3
? Reinforced concrete cannot withstand it for a
long time !
74
2. UHPFRC materials

Ultra compact cementitious matrix
Multilevel fibrous reinforcement
Outstanding mechanical and protective properties

Ductile as steel
Selfcompacting
CEMTECmultiscale developed by Rossi et al.
(2002)
75
UHPFRC composition
Matrix

Silica fume - SF/C 0.26 (mass)
Superplasticizer SP/C 1 (mass, dry extract)
Water/Binder 0.125 to 0.140
Cement 1051 to 1434 kg/m3

76
UHPFRC composition
Fibrous reinforcement
Microfibres Steel wool
Macrofibres L10 mm, D0.2 mm

Steel wool 10 mm/0.2 mm straight fibres
Total dosage 468 - 706 kg/m3 (6 to 9 Vol.)

CEMTECmultiscale developed by Rossi et al.
(2002)
77
Fractured surface of UHPFRC with pulled-out steel
fibres
10 mm
78
3. What is proposed ?
Apply an everlasting winter coat on bridges
? Long-lasting, targeted hardening of
critical zones subjected to severe mechanical and
environmental loads
79
Concept of application
An everlasting wintercoat for bridges

Cast in place waterproof UHPFRC overlay
No thermal treatment, moist curing 8 days
? Pavement applied without waterproofing membrane

80
Concept of application
An everlasting wintercoat for bridges

Combine UHPFRC and rebars to reinforce structures

81
3. Why ?

Rehabilitation works are becoming the dominant
activity in road construction
? Consider impact on a network and society !
Rehabilitations are too often short lived !
Increase load carrying capacity without
increasing deadweight
Limit duration and number of interventions during
service life ? simplify and shorten !
Combine materials in efficient structures !

82
4. Validation

Method of concrete replacement
Study composite UHPFRC-concrete construction
Consider local conditions
Application on inclined substrates
New material
Test on a wide range of scales of time and
dimensions
Provide guidelines for design and use
Validate use with existing facilities and tools

83
Replacement of existing concrete

Major issues
Processing
Monolithic behaviour
Protective function
? Mechanical performance
? Durability

? Successful Structural rehabilitations are a
major challenge

84
Restrained shrinkage
Silfwerbrand (1997)
Stress stiffness free strain degree of
restraint
Stiffness f(Emod, creep/relaxation) ? material
property, Free strain ? material
property Degree of restraint ? structural
property
Typical values

New layer on bridge deck slab 0.4 to 0.6
New layer on stiff beams 0.6 to 0.8
New kerb cast on bridge deck 0.75
Full restraint 1.00

? Study structural configurations with various
degrees of restraint
85
Summary of R D works

Ongoing studies at MCS-EPFL since 1999.
Early age and long term behaviour of composite
members with UHPFRC
Composite structural members with UHPFRC, with
various geometries beams, slabs, walls
Fatigue of composite members with UHPFRC
Tensile behaviour of UHPFRC
Effect of damage on permeability of UHPFRC
Time-dependent behaviour of UHPFRC (creep,
shrinkage)
Combination of UHPFRC with reinforcement bars
Rheological behaviour at fresh state
Numerical modelling and design tools

86
Range of studies
Structural response
Creep, shrinkage, permeability
Resistance
87
Mechanical properties
Denarié et al. (2006)
General overview
UHPFRC NC
Compressive strength MPa 160-250 40
E modulus GPa 48-60 35
Tensile strength MPa 9-20 3
Strain hardening 0.05 - 0.2 0
First crack strength MPa 7-16 3

CEMTECmultiscale

Uniaxial tensile response strain hardening
? Modulus of elasticity 30 higher than normal
concretes
? Tensile strength of matrix 3 to 4 x higher than
normal concrete
Finely distributed multiple cracking during
hardening phase
Similarity with yielding of metals (Luders
strips)

NC Normal Concrete
88
Structural response
Flexural tests on composite beams with UHPFRC,
Habel (2004) ? Effect of new UHPFRC layer
thickness (hu) ? Effect of combination of
UHPFRC with rebars
89
Structural response
NL 10 cm

NL 5 cm
New layer UHPFRC rebars
New layer UHPFRC

Flexural tests on composite beams with UHPFRC,
Habel (2004)
UHPFRC alone significant stiffening
UHPFRC rebars stiffening increase of load
carrying capacity

90
Analytical modelling
UHPFRC
Reinforced Concrete
Tensile response of UHPFRC
Habel (2004)
Compression - UHPFRC
Tension UHPFRC

Composite UHPFRC-Concrete structures
multi-layer systems
Tensile behaviour of UHPFRC can be taken into
consideration
Take eigenstresses into consideration for design
!

91
Main results of R D works - 1

UHPFRC and concrete behave monolithically in
composite members, up tp ULS, Habel (2004).
Interface roughness of 5 mm with wavelength 15 mm
is sufficient for monolithic behaviour, Wuest et
al. (2005), Herwig et al. (2005)
UHPFRC exhibit moderate shrinkage (0.6 after 3
month), and significant viscoelasticity, (creep
coeff 0.8) Habel (2004), Kamen et al. (2005),
AFGC (2002).

92
Main results of R D works - 2

Under full restraint (worst case), eigenstresses
under shrinkage remain moderate ( 50 of
tensile strength), Kamen et al. (2005)
Eigenstresses decrease the apparent tensile
strength of UHPFRC in composite members, Habel
(2004), Clevi (2005), Sadouki et al. (2005) ?
consider for design
Anisotropic orientation of fibres, function of
application ? consider impact on properties

93
Main results of R D works - 3

Very low transport properties for liquids
(sorptivity) and gases, Charron et al. (2004).
Up to equivalent crack openings of 0.1 mm (strain
of 0.1 ) permeability remains very low, Charron
et al. (2004), and behaviour under fatigue
loading is controlled, Herwig (2005).
Self-healing capacity for microcracks
Promissing combination of UHPFRC with rebars, for
reinforcement of structures, with no increase of
dead weight, Brühwiler et al. (2005), Habel
(2004), Wuest et al. (2005).

94
Geometries of application
Habel et al. (2004)

P UHPFRC hu 15 to 30 mm Protection
? PR UHPFRC replacement of corroded rebars
(hu 50 mm) Reinforcement
R UHPFRC additional rebars (hugt50 mm)
Reinforcement

95
Recommandation
UHPFRC

? Apply UHPFRC where it is worth it!
For zones of severe exposure classes (XD2,3,
evt. XA2,3)!
To improve existing or new structures!

96
7. Conclusions

Targeted local hardening of highway structures,
in most critical zones, by using UHPFRC.
Simplification of the construction process.
Reduction of the dead loads (superstructure and
pavement).
? Increase of the performance of existing and new
structures (protection and reinforcement).
Dramatic decrease of the number and severity of
interventions during service life.
Concept has been technically validated on a wide
range of scales and duration

97
Acknowledgements

UHPFRC team of MCS-EPFL Prof. Eugen Brühwiler,
John Wuest, Aicha Kamen, Andrin Herwig, Dr.
Katrin Habel, Prof. J.P. Charron, Roland
Gysler, Sylvain Demierre,
Former collaborators of MCS-EPFL
Partners in Project SAMARIS
Dr. P. Rossi Dr. R. Woodward

98
Guidance on use of surface-applied corrosion
inhibitorsContext and Framework of Guidance

Mark Richardson
University College Dublin

99
Work Package Team

UCD M. Richardson (Team Leader),
C. McNally, T. A. Soylev.
E. Grimes
ZAG A. Legat
TRL M. McKenzie
Sika P. Mulligan, B. Marazzani, M. Donadio
Cardiff University B. Lark
C-Probe Systems Limited /
Structural Healthcare Associates G. Jones

100
Outline

Background
Methodology, Concept, Motivation
Objectives of SACI in a Maintenance Strategy
Reactive and Proactive Context
Primary Factors Influencing Effectiveness
Framework of Guidance for Specifiers of SACI

101
Background to SACI

Methodology
Concept
Motivation

102
Methodology

SACI are applied to mature concrete surfaces
where they are absorbed.
Penetrate through the cover concrete by capillary
action and diffusion.
Form a protective layer on the reinforcement.

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104
Concept
After delay in onset and/or control of
corrosion rate
Before uncontrolled corrosion activity (existing
or future)
105

Evans Diagram
Potential (E)
anodic reaction
cathodic reaction
Current (I)

106

Potential (E)
E corr
I corr
Current (I)

107

After inhibitor application
Potential (E)
Current (I)

108

After inhibitor application
Potential (E)
E corr
I corr
Current (I)

109
Motivation
Benefit of SACI compared to traditional repair
option Reduce disruption to road users during
rehabilitation of structure by time and access
efficiency Sustainability aspect in preventative
maintenance Arrest deterioration before it
becomes significant and costly to repair
110
Objectives of SACI in Maintenance Strategy

Objectives related to overall maintenance
strategy
Specifically consider objectives in Reactive
and Proactive strategies

111
Reactive Maintenance Strategy

Inhibitor may be used to reduce (or at least
prevent an increase) in the rate of corrosion,
thus extending residual service life, unless
extent of corrosion is too advanced.

112
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113

However in a more general context note that
Repair occurs when deterioration is apparent and
possibly significant
Residual capacity of existing structure may be
significantly diminished at time of intervention

114
Proactive Maintenance Strategy

Inhibitor may be used to delay the onset of
depassivation and thereafter positively influence
the rate of corrosion, thus extending residual
service life.

115
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116

Also in a more general context note that
Measures for performance monitoring of the
structure could be included at time of repair.
Inhibitor may be subsequently reapplied (e.g. a
decade later) if performance monitoring indicates
it is warranted, before deterioration becomes
significant.

117
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118
Primary Factors Influencing Effectiveness

Effectiveness is influenced by
Ability of surface to take up the inhibitor
Ability of inhibitor to penetrate the cover
concrete
Ability of inhibitor to form a layer on the
reinforcement
Ability of inhibitor to sustain the protective
layer

119
Appropriateness of SACI

Appropriateness of SACI therefore depends on the
following primary factors
Degree of saturation of concrete
Permeability characteristics of concrete
Corroded state of reinforcement at time of repair
Chloride levels

120
Degree of saturation of concrete

State of surface at time of application (initial
take-up)
Surface condition immediately after application
(wash out)
Influence on permeability

121
Permeability characteristics of concrete

Ease with which inhibitor may penetrate depends
on intrinsic permeability characteristics and
degree of saturation
Permeability also influences ease which other
contaminants may enter post-repair (additional
protection from suitable coating may be required)

122
Corroded state of reinforcement

Inhibitor must form mono-molecular layer on
reinforcement
Ease of formation depends on surface state at
time of repair
Clean or lightly corroded optimal state
Heavily corroded outside inhibitors
effectiveness window

123
Chloride levels

Critical consideration is the relative inhibitor
to chloride concentration
Inhibitor must form a mono-molecular protective
layer and displace chloride ions from the
reinforcement
Competitive surface adsorption reaction between
inhibitors and chloride ions
Inhibitors most effective if applied before
significant build up of chloride concentration

124
Framework of Guidance for Specifiers

Specifiers evaluating or developing a repair
strategy based on surface applied corrosion
inhibitors are encouraged to view it in the
context of a structured approach to deciding on
an optimum repair strategy.
Such a structured approach is presented in
SAMARIS Report D31.

125
Context for Guidance SAMARIS D31
126
SAMARIS D31 Guidance
SAMARIS D25a Guidance
127
Framework of Guidance D25a

Reference
SAMARIS Report D25a
Summary Flowchart

128

Overview of guidance flowchart

129

Overview of guidance flowchart

130

Overview of guidance flowchart

131
Summary

Initial Assessment
Consider findings,
Balance constraints (funding, time, urgency,
traffic disruption etc.) against control of risk
to specifiers satisfaction,
Decide
Go? No go? Go to preview study?

132
Summary

Preview Study Assessment (if used)
Consider findings,
Modify proposed strategy if necessary (e.g.
inhibitor coating rather than inhibitor only),
Balance constraints (funding, time, urgency,
traffic disruption etc.) against control of risk
to specifiers satisfaction,
Decide
Go? No go?

133

Post-repair monitoring
If Go consider also follow up monitoring as
part of a proactive maintenance strategy

134
Further Information

Follow up presentation
(Guidance on use of surface-applied corrosion
inhibitors Detailed Guidance and Case Studies)
SAMARIS Report D25a

135
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136
Optimised assessment of bridges Case study 1 -
Medno bridgeSoft Load Testing

Aleš Žnidaric
Slovenian National Building and Civil
Engineering Institute

137
Assessment of existing bridges

Important factors
condition, level of damage
structural safety
carrying capacity
loading (dead, traffic, dynamic loading)
reliability of data
serviceability (clearances, traffic,
obsoleteness)
service life, importance

What is the carrying capacity?
age, condition, drawings
What is the real behaviour?
influence lines
load distributions
What is the real loading?
in a country, type of road, on specific bridge
dynamic amplification

5-level (step-by-step) assessment
138
Safety assessment

to verify that a structure has adequate capacity
to safely carry or resist specific loading
levels
RgtS
Rating factor

139
Case study Medno bridge

Structure from 1937
no drawings
refurbished in 1997
in very good condition
11.95 m long span
total width 8.5 m
5 RC beams 1.35 m apart
cross beams above abutments, at ¼, ½ and ¾ of the
span
unknown fixity of supports
located on a road with 1150 heavy vehicles ADT
posted to 30 tonnes GVW

140
Carrying capacity

Assumed characteristics of concrete
fc 20 MPa
no information about steel reinforcement
8 bars from profometer test
likely ?25 or 28 mm, assumed 8?22 mm bars of
240/360 MPa steel
RM 867.4 kNm

141
Soft load testing

to check the assumptions made in the model
bridge WIM used to provide
normal traffic data (not in this case)
information about structural behaviour
influence lines
statistical load distribution
impact factors from normal traffic (not in this
case)
only 1 pre-weighed vehicle for BWIM calibration
the bridge need not be closed to traffic

142
BWIM shema
143
Soft Load Testing

Soft load testing

Simply supported RF ltlt 1.0
144
Soft Load Testing

Soft load testing

Simply supported RF ltlt 1.0
Measured RF gtgt 1.0
Message Check, how bridges really behave.
145
Soft Load Testing

Load distribution
normally guestimation
bridge WIM evaluates it statistically

146
Selection of capacity reduction factor

Capacity reduction factor
F BR e -?.ßc.V
SI procedure accounts for
condition of the structure
reliability of data
redundancy of structure
method of calculation
Medno bridge
F 0.86

147
Selection of safety factors

Dimensions taken on site
Safety factor for traffic loading

?G 1.2
?Q 1.9
?Q 1.7
?Q 1.6
148
Structural safety of Medno bridge

Calibrated structural model
Loading scheme with 2 4-axle rigid 38-ton trucks,
one in each lane

Loading scheme with 81-ton 8-axle vehicle in one
lane and rigid 38-ton truck in the other

Room for further optimisation of analysis
149
Conclusions

on Medno bridge soft load testing proved
beneficial
2004 assessments for special transports for the
Slovene Road Administration
13 posted bridges assessed
11 proved safe even for a 165-tonnes special
vehicle with 12 axles
for the rest missing data on carrying capacity
on shorter bridges normal traffic worse than
special transports

150
Optimised assessment of bridges Case study 2
Danish examples

Alan OConnor
Rambøll

151
Problem, idea and motivation

Problem
1) Lack of load carrying capacity or exceedance
of structural/performance limit state due to
weak bridges
deteriorated/(ing) bridges
Increasing loads

2) Low budgets for strengthening and/or
rehabilitation where required Idea 1) Demonstrati
on of higher capacity through Probabilistic
safety assessments incorporating better
calculation/response models Principal
Motivation Cost saving through Budget
Optimisation
152
Safety approaches for assessment of existing
bridges

The general approach
Assessments based upon deterministic
codes for both (a) New bridges and (b) Existing
bridges
Generalisation
Partial safety factor format
Deterministic Load specification
Many types of bridges

Benefit Efficient and easy to use Drawback Costly
in case of lack of capacity may result in
unnecessary repair/rehabilitation
153
The individual approach

Concept
Not necessarily have to fulfill the requirements
of a general code rather the Overall requirement
for the safety level must be satisfied on a
individual basis
Purpose
Cut strengthening or rehabilitation costs without
compromising safety level
Method Probabilistic-based assessment
Site specific modelling of specific
conditions/structure
Traffic load
Capacities
Response Models

Bridge specific code is obtained
154
Decision Process
155
Case Studies

Practical experience The Danish Road
Directorate has saved more than 50 million USD

156
Case Studies - Savings
Savings gt 4 mio.
Savings gt 20 ml.
Savings gt 0.5 ml.
Savings gt 15 ml.
Savings gt 2 ml.
157
Case Studies - Savings
Savings gt 0.3 ml.
Savings gt 0.5 ml.
Savings gt 1.0 ml.
Savings gt 2.0 ml.
Savings gt 2.0 ml.
158
Probability based Maintenance Management
159
Practical 10-phase procedure
0. Fact-finding 1. Formulation of problem
2. Safety requirements 3. Deterministic
models for failure 4. Probability-based
safety-model for critical failure modes. 5.
Stochastic variables 6. Safety of the
non-deteriorated bridge 7. Safety of
deteriorated bridge 8. Analysis of repair and
rehabilitation options 9. Requirements for the
visual appearance of the bridge 10. Cost-optimal
management plan using decision analysis
to determine optimal rehabilitation options
SAFETY
MANAGEMENT
160
Skovdiget Bridges Location / OverviewSAVING
20ml.
WestBridge
EastBridge

Post tensioned concrete
box-girder bridges
12 spans, 220 m long
Carries a 4-lane highway

161
History
West Bridge East bridge 1965-1967
Construction Construction 1978
Major rehabilitation 1978-1999 Inspe
ction 4 times Principal Inspection a year.
Load testing every 5 years. every 5
years. Normal M R procedure. Bridge
in bad Bridge in good condition. condition
. 1998-2000 Implementation of probabilistic-ba
sed management plan.
162
Design, Deterioration Assessment

Poor workmanship during construction
un-injected or poorly injected post-tensioned
cable ducts
insufficient and poor drainage
area around gulley poorly made
bad waterproofing

Modelling of stochastic variables
Modelling of strengths
concrete, reinforcement steel, cables
Modelling of loads
total traffic load
dynamic amplification factors
transverse distribution of vehicles
Model uncertainties
Prediction of the deterioration

Deterministic analysis of bridge failure modes
Main girders, moment and shear failure
Shear failure of transverse girders (above
columns)
Transverse ribs between main girders 3 and 4
East and west cantilever wing
Identifying areas with most severe deterioration
Identifying critical combinations

Fast Slow Service
Emergency Bicycle lane lane
lane lane lane
footway
Gulley
Main girder 4
Main girder 3
163
Calculation of safety allowing for deterioration
Development of the safety index

Maintenance Management Options
Traffic, repair and information options
Traffic options
- Weight restrictions
Repair/strengthening - or replacement - options
- Minor / major repair - or - strengthening
- Preventive actions
- Replacement
Improvement of Information level
- Inspections to update estimate of current
deterioration
- Test loading
- Determine actual weight the bridge
- Monitoring system
- More advanced analysis and response models
- Extended routine and special inspections

A Safety-based management plan is established and
implemented for Skovdiget West
Extended lifetime gt 15 years Cost savings gt 20
million
The Danish Road Directorate is now using the
methodology for other bridges
The safety level is not compromised
A rational methodology is implemented for
practical application
Probabilistic-based assessment of bridges cuts
strengthening or rehabilitation costs. The cost
savings can be significant

www.vd.dk
164
Conclusions

Reliability based assessment of bridges and
Probability Based Maintenance Management cuts
strengthening or rehabilitation costs
The safety level is not compromised
A well established methodology is implemented
for practical application
The cost saving can be millions of per year

165
(No Transcript)
166
Ultra High Performance Fibre Reinforced
Composites (UHPFRC) for rehabilitation - 2. Case
study first application

Jean-Christophe Putallaz SRCE/VS
Emmanuel Denarié MCS/EPFL

167
OUTLINE

Rehabilitation strategy
First application
Conclusions
Acknowledgements

168
Rehabilitation strategy

Limit costs (construction and life-cycle)
Decrease number and duration of interventions
Provide sufficient durability

? Promote STRATEGY A
169
2. First application
Site application 1 - 2004
Structural response
Creep, shrinkage, permeability
Resistance
170
First application

Rehabilitation and widening of the Bridge over
river La Morge - Switzerland

Execution October November 2004
171
GEOGRAPHICAL LOCATION

? Swiss alps, Valley nearby Sion, 480 m above s.l
Secondary road with sustained traffic
Heavy salt spraying in winter

172
Prior to rehabilitation
Downstream kerb
Upstream kerb

No waterproofing membrane,
Kerbs severely damaged by chloride induced
corrosion

173
Concept of the intervention
Span 10 m

No waterproofing membrane
Protective function provided by UHPFRC
Widening of the bridge
Prefabricated UHPFRC kerb downstream
Thin UHPFRC overlay (3 cm) applied on deck
UHPFRC rehab. kerb usptream

Span 10 m
174
Construction joint for UHPFRC
175
Prefabricated downstream kerb
176
Prefabricated kerb in UHPFRC - joint
177
UHPFRC materials

Cement CEM I 52.5 (low C3A)
Fine quarz sand (Dmax lt 0.5 mm)
Silica fume - SF/C 0.26
Superplasticizer 1 dry extract
Steel wool 10/0.2 mm steel fibres
Total fibres 9 Vol. or 706 kg/m3)

Basis CEMTECmultiscale - Rossi et al. (2002) ?
No thermal curing ? Protection with plastic sheet
8 days moist curing
178
UHPFRC materials
Recipe Cement kg/m3 W/B -- W/C -- Application
CM22 1410 0.131 0.165 Rehabilitation Upstream kerb
CM23 1434 0.125 0.155 Downstream kerb overlays

CM 23 tolerates slope up to 2.5
Both recipes are selfcompacting
Slump flow 400 mm

179
Preparation of the UHPFRC

Concrete plant mixer with 500 to 750 litres
capacity
300 litres UHPFRC pro batch
3 batches 900 litres in 45 minutes
900 litres pro truck - 635 kg steel fibres per
truck !

180
On the site
Application on ½ road downstream october 22,
2004
181
Processing of the UHPFRC
The thixotropic, selfcompacting UHPFRC, is
handled using simple tools (Photo A. Herzog)
182
In-situ air permeability testing
Air permeability tests after Torrent et al.
(1995) ? Extremely low kT values measured on
bridge
183
Comparative uniaxial tensile behaviour
Denarié et al. (2006)
184
Uniaxial tensile tests on UHPFRC
Denarié et al. (2006)
fct 13.5 MPa (mean) ehardening 1.5 (mean)
Test results on 5 specimens, at 28 days
185
Cost analysis

Comparison of three alternatives
Executed project with UHPFRC and no waterproofing
membrane
Similar case with rehabilitation mortar and
waterproofing membrane
Similar case with cheaper (- 30 ) UHPFRC and no
waterproofing membrane

Case Relative construction costs
A 112
B 100
C 107
Realized
186
The bridge, after first winter
187
Detail of UHPFRC, after first winter
Prefabricated
UHPFRC cast on site
View of the surface of the prefabricated kerb
with UHPFRC, with superficial corrosion of steel
fibres tips near to the surface.
188
Conclusions of first application

UHPFRC CEMTECmultiscale was easy to produce and
cast on site with standard equipments.
Quality of the UHPFRC was verified in-situ and in
the laboratory. Excellent properties were
achieved.
Waterproofing membrane not necessary with UHPFRC.
Bituminous layer can be applied after 8 days on
UHPFRC, instead of several weeks for normal
concrete.
Superficial corrosion of steel fibres on UHPFRC
skin, is linked to processing.
Although a purely superficial concern, has to be
mitigated by adapted processing techniques.

189
Owners point of view

The main advantages of this technique are
? Shortening of duration of works, quicker
reopening of traffic lanes, and longer
durability.
? Significant savings in terms of reduced traffic
disturbances and associated indirect costs.
? Reduction of rehabilitation layer thickness and
capacity to reinforce without increasing
deadweight.
? Prevent costly reinforcement of main parts of
the structure.
? Application by local contractors, with standard
equipments.

SRCE - DTEE CANTON DU VALAIS
190
7. Conclusions

Targeted local hardening of highway structures,
in most critical zones, by using UHPFRC.
Simplification of the construction process.
Reduction of the dead loads (superstructure and
pavement).
? Increase of the performance of existing and new
structures (protection and reinforcement).
Dramatic decrease of the number and severity of
interventions during service life.
Concept has successfully demonstrated its
technical maturity and economical feasibility in
a first full scale application.

191
What is the future ?
Site application 2 - 2007
Site application 1 - 2004
Structural response
? Why not you ?
Creep, shrinkage, permeability
Resistance
192
Partners of the project
Owner Département des Travaux Publics du canton
du Valais, Sion, Suisse, Service des routes et
Cours d'eau, Section du Valais central/Sion,
Switzerland. Concept and supervision Laboratory
for Maintenance and Safety of Structures, Ecole
Polytechnique Fédérale de Lausanne (EPFL),
Switzerland Advice for the UHPFRC recipes and
processing Dr. P. Rossi, Laboratoire Central des
Ponts et Chaussées (LCPC), Paris,
France. Execution plans and local direction of
works PRA ingénieurs conseil SA, rue de la
Majorie 9, CH-1950 Sion, Switzerland,
Production of UHPFRC, realisation of
prefabricated UHPFRC kerb and reinforced concrete
beam Proz Frères SA, matériaux de construction,
CH-1908 Riddes, Switzerland, Contractor
Evéquoz SA, rue des Peupliers 16, CH-1964
Conthey, Switzerland,
193
Acknowledgements

UHPFRC team of MCS-EPFL Prof. Eugen Brühwiler,
John Wuest, Aicha Kamen, Andrin Herwig, Dr.
Katrin Habel, Prof. J.P. Charron, Roland
Gysler, Sylvain Demierre,
Former collaborators of MCS-EPFL
Partners in Project SAMARIS
Dr. P. Rossi Dr. R. Woodward
Service des Routes et Cours dEau DTEE SRCE
Canton du Valais

194
Guidance on use of surface-applied corrosion
inhibitors

Workshop on detailed guidance and
Case Studies
M. Richardson
UCD

195
Outline

Initial Assessment
Preview Study option
Post-repair Monitoring option
Case Study Assessment and Monitoring
Kingsway Bridge
Case Study Post-repair monitoring
Fleet Flood Span Bridge

196

Initial Assessment

197
Summary of Guidance - 1
198
Issues in Initial Assessment

Extremes of in-service environmental conditions
Degree of saturation of concrete
Chloride levels
Permeability and carbonation
Corroded state of reinforcement at time of repair
Ecological constraints

199
Issues in Initial Assessment

Extremes of in-service environmental conditions
Degree of saturation of concrete
Chloride levels
Permeability characteristics of concrete
Corroded state of reinforcement at time of repair
Ecological constraints

200
Issues in Initial Assessment

Extremes of in-service environmental conditions
Degree of saturation of concrete
Chloride levels
Permeability characteristics of concrete
Corroded state of reinforcement at time of repair
Ecological constraints

201
Extremes of environmental conditions
Environment Indicative Temperature Potential Consequence
Sustained low temperatures -5oC Alteration in the physical nature of the inhibitor, with implications for its mobility in concrete. Temperature limit of 5C is only applicable for the storage condition. Application to be carried out above 5C.
Frequent high temperatures 40oC Potential loss of volatile material to the atmosphere. Coating the concrete surface may be an option to reduce evaporation loss.
202
Degree of saturation of concrete
Moisture State Indicative Example Possible Consequence
Permanently saturated Elements of highway structures predominantly below the water level of a lake Inhibitor take up by absorption would be low. Subsequent penetration would not be assisted by capillary action. Note corrosion would be low in these areas if oxygen access is equally restricted.
Frequent and regular wetting cycles Elements of coastal highway structures within the tidal zone Potential washout of inhibitor immediately after application. Inadequate concentration at the reinforcement.
203
Chloride levels
Chloride State Indicative Free Chloride Ion at Level at Reinforcement Possible Consequence
Low 0.5 Chloride ion by mass of cement Corrosion inhibitor potentially viable as a preventive maintenance strategy before any significant active corrosion takes place.
Moderate 1 Chloride ion by mass of cement Corrosion inhibitor may be effective if a satisfactory inhibitor to chloride ion concentration ratio is achieved much depends on existing degree of corrosion. Protective measures to prevent further chloride build up are recommended in chloride-rich environments.
continued
204
Chloride levels
continued
Chloride State Indicative Free Chloride Ion at Level at Reinforcement Possible Consequence
High 1 2 Chloride ion by mass of cement Corrosion inhibitor dosage level may have to be increased beyond typical manufacturers recommendation and additional protective measures required. May take the technique beyond its recommended effectiveness window, introducing higher risk.
Very high gt 2 Chloride ion by mass of cement Corrosion inhibitor unlikely to be a successful component of the repair strategy.
205
Permeability and carbonation
Carbonation State Concrete Permeability Possible Consequence
Cover fully carbonated Moderate Inhibitor potentially effective.
Cover fully carbonated High Inhibitor potentially effective initially but reservoir may not be retained in concrete reducing effectiveness over time. May need additional measures such as a suitable coating.
206
Corroded state of reinforcement
Existing Corrosion Rate Indicative Corrosion Rate over a sustained period Possible Consequence
Low to Moderate lt 0.5 µA/cm2 lt 5 µm/year Best scenario possible with inhibitor used as part of a proactive preventive maintenance strategy.
Moderate to High 0.5 1.0 µA/cm2 5 - 10 µm/year State of reinforcement is potentially suitable for consideration of corrosion inhibitor treatment.
continued
207
Corroded state of reinforcement
continued
Existing Corrosion Rate Indicative Corrosion Rate over a sustained period Possible Consequence
High 1.0 - 10 µA/cm2 10 - 100 µm/year State of reinforcement will depend on corrosion rate lies - effectiveness of the inhibitor correspondingly influenced. Higher risk at higher corrosion rate. Corrosion monitoring recommended in case of higher corrosion rates.
Very High gt 10 µA/cm2 gt 100 µm/year Reinforcement may be heavily corroded - corrosion inhibitor is unlikely to be a successful component of the repair strategy.
208
Ecological constraints