Design Manual for Roads and Bridges
Highway Structures & Bridges
Inspection & Assessment
CS 466
Risk management and structural assessment
of concrete half-joint deck structures
(formerly IAN 53/04 and BA 39/93 (plus part of BD 44/15))
Revision 0
Summary
The use of this document enables the safety and serviceability of half-joints to be managed and
assessed, providing key information that is required to manage risks and maintain a safe and
operational network.
Application by Overseeing Organisations
Any specific requirements for Overseeing Organisations alternative or supplementary to those given in this document
are given in National Application Annexes to this document.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage
of this document to the dedicated Highways England team. The email address for all enquiries and feedback is:
Standards_Enquiries@highwaysengland.co.uk
This is a controlled document.
CS 466 Revision 0
Contents
Contents
Release notes
4
Foreword
Publishing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contractual and legal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Introduction
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assumptions made in the preparation of this document . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Abbreviations and symbols
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Terms and definitions
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1. Scope
Aspects covered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of GG 101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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2. Risk management process and prioritisation
Risk management report . . . . . . . . . . . . .
Initial review . . . . . . . . . . . . . . . . . .
Risk assessment for structural assessment
Structural review . . . . . . . . . . . . . . .
Structural assessment . . . . . . . . . . . .
Risk assessment for management . . . . .
Management plan . . . . . . . . . . . . . .
Prioritisation of half-joint structures . . . . . . . .
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3. Initial review
4. Risk assessment for structural assessment
Risk assessment . . . . . . . . . . . . . . . . .
Primary risks . . . . . . . . . . . . . . . . . . .
Condition risk . . . . . . . . . . . . . . . .
Structural risk . . . . . . . . . . . . . . . .
Secondary risks . . . . . . . . . . . . . . . . .
Consequential risk . . . . . . . . . . . . .
Vulnerable details risk . . . . . . . . . . .
Half-joint form risk . . . . . . . . . . . . .
Other risks . . . . . . . . . . . . . . . . .
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5. Structural review
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6. Structural assessment
Assessment processes and basis of assessment . . . . .
Limit states . . . . . . . . . . . . . . . . . . . . . . .
Assessment actions and assessment action effects .
Assessment of resistance . . . . . . . . . . . . . . .
Verification . . . . . . . . . . . . . . . . . . . . . . .
Methodology for structural analysis . . . . . . . . . . . . .
Assessment based on strut-and-tie analysis . . . . .
Assessment based on mechanism analyses . . . . .
Non-linear finite element analysis . . . . . . . . . . . . . .
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CS 466 Revision 0
7. Risk assessment for management
Primary risks . . . . . . . . . . . . .
Condition risk . . . . . . . . . .
Structural risk . . . . . . . . . .
Secondary risks . . . . . . . . . . .
Contents
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8. Management plan
Structures assessed to have sufficient capacity . . . . . . . . . . .
Structures assessed to have sufficient capacity but with concerns .
Sub-standard structures . . . . . . . . . . . . . . . . . . . . . . . .
Management measures . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance inspections . . . . . . . . . . . . . . . . . . . .
Maintenance activities . . . . . . . . . . . . . . . . . . . . . .
Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Plan for interim measures . . . . . . . . . . . . . . . . . . . .
Long term solutions . . . . . . . . . . . . . . . . . . . . . . .
Interim measures . . . . . . . . . . . . . . . . . . . . . . . . .
Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Strengthening . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . .
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9. Normative references
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10. Informative references
33
Appendix A. Half-joint terminology
34
Appendix B. Model documents
B1 Model risk management report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B2 Model priority list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Appendix C. Guidance on risk assessment
C1 General . . . . . . . . . . . . . . . . . .
C2 Primary risk rating . . . . . . . . . . . .
C2.1 Condition risk . . . . . . . . . .
C2.2 Structural risk . . . . . . . . . . .
C3 Secondary risks . . . . . . . . . . . . .
C3.1 Consequential risk . . . . . . . .
C3.2 Vulnerable details risk . . . . . .
C3.3 Half-joint form risk . . . . . . . .
C3.4 Other risks . . . . . . . . . . . .
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Appendix D. Simplified method for SLS assessment of half-joints
D1 Simplified analysis for calculation of crack widths in half-joints . . . . . . . . . . . . . . . . . . . . . . . .
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Appendix E. Illustrative examples of strut-and-tie models of half joints
E1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E2 Illustrative examples of strut-and-tie models for typical features of half-joints . . . . . . . . . . . . .
E2.1 Presence of post-tensioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E2.2 Detailing of horizontal nib reinforcement . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E2.3 Bent-up diagonal reinforcement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E2.4 Corrosion or spalling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E2.5 Longitudinal reinforcement not enclosed by links . . . . . . . . . . . . . . . . . . . . . . . .
E2.6 Loads applied through discrete bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E2.7 Transition from solid half-joint to discrete beam webs . . . . . . . . . . . . . . . . . . . . . .
E3 Illustrative examples of strut-and-tie models enabling analysis of plastic redistribution in half-joints
E3.1 Using statically indeterminate models to control tie forces . . . . . . . . . . . . . . . . . . .
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CS 466 Revision 0
Contents
E3.2 Using superposition of complementary strut-and-tie systems . . . . . . . . . . . . . . . . . . . .
E3.3 Using strut-and-tie models with wider struts and nodes. . . . . . . . . . . . . . . . . . . . . . . .
3
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76
CS 466 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Mar 2020
CS 466 replaces IAN 53/04 and BA 39/93, and also replaces the content
regarding half-joint assessment previously in BD 44. This full document has
been re-written to make it compliant with the new Highways England drafting
rules.This document contains a significant amount of new content relating to
risk management and structural assessment methods, to bring the documents
up to date, align with the related DMRB documents and align with industry
practice.
4
CS 466 Revision 0
Foreword
Foreword
Publishing information
This document is published by Highways England.
This document supersedes BA 39/93 and IAN 53/04, which are withdrawn.
Contractual and legal considerations
This document forms part of the works specification. It does not purport to include all the necessary
provisions of a contract. Users are responsible for applying all appropriate documents applicable to
their contract.
5
CS 466 Revision 0
Introduction
Introduction
Background
The use of this document enables the safety and serviceability of half-joints to be managed and
assessed, providing key information that is required to manage risks and maintain a safe and
operational network.
This document has been developed to replace the documents IAN 53/04 and BA 39/93, and also
replaces the content previously in 7.2.4.2 of BD 44/15.
The approach for risk management of half-joint structures has been developed based on current
guidance towards risk management of structures from the industry, as well as GG 104 [Ref 10.N].
The approach for structural assessment of half-joint structures has been developed to enable typical
half-joint structures to be assessed without departures from standard, even where they include details
that donot conform with modern design requirements.
This document has been developed in combination with new content in CS 455 [Ref 12.N], including
relevant content about using strut and tie analysis, plastic analysis, bond resistance, effects of low
cover and effects of deterioration.
The development of this document has included the following aspects:
1) improvements to the technical content previously included in section 7.2.4.2 of BD 44/15;
2) collation of the useful parts of the previous document BA 39/93, particularly with respect to SLS, and
the ULS content from BD 44/15 section 7.2.4.2;
3) incorporation of strut and tie methods as provided in BS EN 1992 [Ref 2.I], to avoid the need for
departures from standard in order to use strut and tie models for assessment of half-joints;
4) incorporation of guidance on the safe application of a range of analysis methods that can be used as
part of a half-joint assessment, including strut-and-tie modelling, mechanism analyses, and
non-linear finite element analyses;
5) validation of new content based on research relating to the effect of deterioration and detailing on
half-joint assessment, including a programme of laboratory testing of half-joints.
Assumptions made in the preparation of this document
The assumptions made in GG 101 [Ref 7.N] apply to this document.
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Abbreviations and symbols
Abbreviations and symbols
Abbreviations
Abbreviation
Definition
AIP
Approval in principle
SLS
Serviceability limit state
TAA
Technical Approval Authority
ULS
Ultimate limit state
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Abbreviations and symbols
Symbols
Symbol
Definition
RC
Condition risk
RD
Structural risk
RD1
Structural risk relating to the as built detailing of the half joint
RD2
Structural risk relating to the previous structural assessment findings specific to the half
joint
RQ
Consequential risk
RV
Vulnerable details risk
RF
Half joint form risk
RO
Other risks
kcover
Bond reduction factor due to low cover
acon
Confinement factor
α
Angle of the relative displacement relative to the discontinuity
c
Concrete cover
ϕ
Effective bar or strand diameter
ϕA
Virtual rotation in upper bound mechanism
δA
Virtual displacement in upper bound mechanism
δi
The components of the displacement for the mechanism being analysed, determined at
the points of application for each load in the direction of the applied load
δrj
The relative displacements at the discontinuity for each reinforcing bar or pre-tensioning
strand, measured in the direction of the respective reinforcing bar or pre-tensioning
strand
E
Energy dissipated in a mechanism analysis
Ecl
Energy dissipated in the concrete per unit length of discontinuity
Faj
The assessment tension resistances that can be developed in each reinforcing bar or
bonded pretensioning strand crossing the discontinuity in an upper bound mechanism,
determined at the position of the discontinuity
Q*ai
The magnitudes of the assessment loads, including the respective partial factors for
actions, as defined in BD 21 [Ref 9.N]
ν
Effectiveness factor for concrete
fcu
Characteristic concrete cube strength (or worst credible concrete cube strength)
γmc
Partial factor for concrete strength
γf 3
Partial factor as defined in BD 21 [Ref 9.N]
u
Magnitude of the relative displacement at a discontinuity
b
Breadth of the member
W
Work done by the assessment loads
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Terms and definitions
Terms and definitions
Terms and definitions
Terms
Definitions
Immediate risk structure
Structures that represent an immediate and unacceptable safety risk to
the public. See also CS 470 [Ref 9.N].
Lower-bound analysis
Lower-bound analyses are based on finding any system of internal
forces that are everywhere in equilibrium with the applied loads and
which nowhere exceed yield.
Provisionally sub-standard
Structures that are deemed to be sub-standard without an assessment
*(for example scour, impact damage, deterioration) or assessed to have
sub-standard load capacity at any stage during the assessment
process, regardless of whether they are considered appropriate to
progress the assessment further. See also CS 470 [Ref 9.N].
Structural assessment
The process of determining in terms of vehicle loading the load that an
existing structure can carry with an acceptable probability without
suffering serious damage that can endanger any persons on or near
the structure.
Sub-standard structures
Structures found to be sub-standard in terms of meeting the
carriageway loading requirements given in CS 454 [Ref 1.N]or by other
means (as examples by scour, impact damage, deterioration), or after
carrying out an appropriate assessment. See also CS 470 [Ref 9.N].
Upper-bound analysis
Upper-bound analyses are based on a comparison of the work done by
the loads and the energy dissipated in the structure during the
mobilisation of a compatible failure mechanism.
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1.
1. Scope
Scope
Aspects covered
1.1
This document shall be used for the risk management and structural assessment of concrete half-joint
deck structures.
NOTE 1
This document covers concrete half-joint deck structures, including:
1) reinforced concrete half-joints;
2) post-tensioned concrete half-joints;
3) pretensioned concrete half-joints.
4) concrete parts of steel/concrete composite half-joints.
NOTE 2
This document does not cover steel-to-steel half-joints.
NOTE 3
Half-joint deck structures include structures with uplift half-joints.
NOTE 4
Appendix A explains the terminology used to describe elements of the half-joint.
1.2
This document shall be used to prioritise half-joint structures for structural assessment and risk
management.
NOTE
The requirements for managing sub-standard structures, including immediate risk structures, are found
in CS 470 [Ref 9.N].
Implementation
1.3
This document shall be implemented forthwith on all schemes involving the management or
assessment of half-joint structures on the Overseeing Organisations' motorway and all-purpose trunk
roads according to the implementation requirements of GG 101 [Ref 7.N].
Use of GG 101
1.4
The requirements contained in GG 101 [Ref 7.N] shall be followed in respect of activities covered by
this document.
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2. Risk management process and prioritisation
2.
Risk management process and prioritisation
2.1
All concrete half-joint structures shall be managed by an ongoing process of review, risk assessment
and risk management.
2.1.1
The process of review, risk assessment and risk management should include:
1) review of existing priority list, where available;
2) review triggers.
NOTE 1
Review triggers can include the following:
1) structures with a change in condition that could affect the load carrying capacity;
2) structures with half-joints where no previous structural assessment exists;
3) structure with half joints which have never had a half-joint specific special inspection undertaken;
4) structures with half-joints where there are doubts about the validity of the previous assessment
methodology or assumptions made;
5) families of structures known to have deficient half-joints;
6) structures affected by or incorporated in new schemes;
7) changes to the use of the structure, for example altered lane markings;
8) structures where long term solutions have been implemented and half-joint detail is retained.
NOTE 2
Long term solutions can include repair, strengthening and replacement.
2.1.2
Where a half-joint structure is currently subject to an existing half-joint management plan, then the
structure should continue to be managed using the existing half-joint management plan until a new
review trigger occurs.
2.2
Where a new review trigger occurs to a half-joint structure currently subject to an existing half-joint
management plan, then the half-joint structure shall be managed using the risk management process
described in this document and added to the priority list.
2.3
The risk management process shall comprise the following stages, as illustrated in Figure 2.3:
1) initial review;
2) risk assessment for structural assessment;
3) structural review;
4) structural assessment;
5) risk assessment for management;
6) management plan.
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2. Risk management process and prioritisation
Figure 2.3 Half-joint structures risk management process flowchart
NOTE 1
Each stage of the risk management process is described in Sections 3 to 8 of this document.
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2. Risk management process and prioritisation
NOTE 2
The structural assessment outputs refer to whether a structure is structurally assessed as being
capable of carrying normal traffic (pass) or not (fail) in accordance with CS 454 [Ref 1.N].
2.4
Risk assessments shall be undertaken in accordance with GG 104 [Ref 10.N].
2.5
Sub-standard half-joint structures shall be managed in accordance with CS 470 [Ref 9.N] and in
conjunction with this document.
2.6
The risk management process in Figure 2.3 shall be revisited for a half-joint structure in the following
situations:
1) new review triggers occur; or,
2) following a new principal inspection.
Risk management report
2.7
The risk management report shall be the means by which the key inputs, outputs, justification and
decisions from the risk management process is recorded and agreed.
NOTE
A model risk management report is provided in Appendix B.
2.8
The risk management report shall be a live document, started during the initial review, then reviewed
and updated at each stage of the risk management process.
2.9
The risk management report shall be submitted to the Overseeing Organisation following completion of
each stage of the risk management process.
2.10
Where managed through CS 470 [Ref 9.N], a summary of the sub-standard structure management plan
shall be included in the risk management report.
Initial review
2.11
The following shall be included in the risk management report after the initial review:
1) the inputs informing the desk study, including review triggers;
2) whether there is need to undertake a new inspection of the half-joint;
3) the findings from the desk study;
4) recommendations for investigations to be undertaken, e.g. where additional information is needed to
complete the risk assessment.
Risk assessment for structural assessment
2.12
The risk management report shall record the inputs and outputs from the risk assessment for structural
assessment stage.
NOTE 1
The inputs for the risk assessment include:
1) primary and secondary risks used in the risk assessment;
2) justification and evidence informing the determination of the risk ratings.
NOTE 2
The outputs for the risk assessment include:
1) the risk rating for each primary or secondary risk;
2) the primary risk rating;
3) where applicable, the refined primary risk rating;
4) where applicable, the secondary risk rating.
NOTE 3
Risks and risk ratings are described in Sections 4 and 7 of this document.
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2. Risk management process and prioritisation
Structural review
2.13
The risk management report shall record a summary of the outputs from the CS 451 [Ref 11.N]
structural review.
Structural assessment
2.14
The risk management report shall record a summary of the findings and recommendations from the
structural assessment.
Risk assessment for management
2.15
The risk management report shall record the inputs and outputs from the risk assessment for
management stage.
NOTE 1
The inputs for the risk assessment include:
1) primary and secondary risks used in the risk assessment;
2) justification and evidence informing the determination of the risk ratings.
NOTE 2
The outputs for the risk assessment include:
1) the risk rating for each primary or secondary risk;
2) the primary risk rating;
3) where applicable, the refined primary risk rating;
4) where applicable, the secondary risk rating.
NOTE 3
Risks and risk ratings are described in Sections 4 and 7 of this document.
Management plan
2.16
The risk management report shall include a summary of the risk management plan and recommended
risk management measures for the structure.
Prioritisation of half-joint structures
2.17
Where the structural assessment and management of numerous half-joint structures is required, they
shall be prioritised based on the outputs from the risk assessment process.
NOTE
A model prioritisation list is provided in Appendix B.
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3. Initial review
3.
Initial review
3.1
An initial review shall be carried out as a desk study to evaluate whether the information available is:
1) sufficient to enable a risk assessment to be carried out;
2) current; and,
3) valid.
3.2
The initial review shall be undertaken by reviewing the following record information:
1) the most recent risk assessment;
2) as-built drawings, construction records and other as-built information;
3) principal, general or special inspection reports;
4) recommendations from previous inspections and maintenance records; and,
5) previous structural assessments and recommendations.
3.2.1
A review of any previous structural assessments should cover the following:
1) whether a specific half-joint assessment has been completed;
2) the assessed load carrying capacity of the half-joint;
3) the availability and validity of the assessment and check certificates; and,
4) the availability and validity of the assessment report.
NOTE
Structural assessments are not valid for the management process described in this document if they
have not specifically assessed the capacity of the half-joint.
3.2.2
Where previous inspections of the half-joint structure are unavailable or a change in condition is likely
since the structure was last inspected, then an inspection of the half-joint should be undertaken,
following agreement with the Overseeing Organisation.
3.2.3
The type and extent of inspection should be targeted at obtaining the required information for the initial
review or evaluating the change in condition.
3.2.4
Where additional information is needed to complete the risk assessments, a recommendation for
investigations to be undertaken should be included in the risk management report.
3.2.5
The risk management report should include recommendations on the timescales for undertaking the
investigations.
3.3
Where the initial review finds evidence that the half-joint could be at immediate risk or provisionally
sub-standard, then the structure shall be managed in accordance with CS 470 [Ref 9.N].
NOTE
Evidence indicating that a half-joint could be at immediate risk can include:
1) significantly deteriorated condition;
2) recent event causing significant defects;
3) signs of a failure mechanism developing.
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4.
4. Risk assessment for structural assessment
Risk assessment for structural assessment
Risk assessment
4.1
A risk assessment shall be completed to prioritise half-joint structures for structural assessment.
NOTE 1
The output from the risk assessment process assigns a risk rating to each structure to enable
prioritisation for structural assessment.
NOTE 2
Example risk ratings are as follows:
1) very high;
2) high;
3) medium;
4) low.
4.2
The following primary risks shall be included when completing a risk assessment to determine a
primary risk rating for prioritising structural assessments:
1) condition risk, RC ; and,
2) structural risk, RD .
NOTE 1
The primary risks are used to assess the risk of the structural failure of the half-joint based on the
following:
1) RC representing the likelihood of structural failure due to condition risks being realised;
2) RD representing the likelihood of structural failure due to structural capacity risks being realised; and,
3) the severity of the consequences at this stage is taken as being very high as it involves a half-joint
structure failure which could lead to collapse.
NOTE 2
Guidance on each of the primary risks listed above and how to use them is provided in Appendix C.
4.2.1
The primary risk rating should be used to determine an initial priority list for the structural assessment
of a group of half-joint structures.
4.2.2
The effects from the combination of condition and structural risk should be assessed when assigning a
risk rating for the primary risks.
NOTE
An example of how the risk rating of a structure changes due to effects in combination can be found in
Appendix C.
4.2.3
The following secondary risks may be used to refine the primary risk rating of a half-joint structure:
1) consequential risk, RQ ;
2) vulnerable details risk , RV ;
3) half-joint form risk, RF ;
4) other risks, RO .
NOTE 1
Secondary risks can be used to either increase the primary risk rating or to prioritise between a number
of structures with the same primary risk rating.
NOTE 2
Where secondary risks are used to increase the primary risk rating, this is referred to as the refined
primary risk rating.
NOTE 3
Where secondary risks are used to prioritise between a number of structures with the same primary risk
rating, this is referred to as the secondary risk rating.
NOTE 4
Guidance on each of the secondary risks, how to use them in combination with the primary factors is
provided in Appendix C.
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4. Risk assessment for structural assessment
Primary risks
Condition risk
4.3
The risk rating for the condition risk RC , shall be determined based upon the current condition of the
half-joint.
4.4
The current condition of the half-joint shall be verified from photographs and information available
within inspection information.
NOTE
Details on appropriate inspection methods for half joints can be found in CIRIA C764 [Ref 5.N] .
4.4.1
Conclusions made in inspection reports should be verified through reviewing the site inspection
information.
4.5
The half-joint shall be appraised for possible combinations of defects on the structural capacity.
NOTE 1
The effects on the strength of the section from combinations of defects can be greater than the sum of
individual defects (e.g. the interaction between poor longitudinal reinforcement anchorage and the
provision of insufficient shear reinforcement). Individual defects can have a limited impact on the
capacity (due to alternative load paths being formed), but for multiple defects, alternative load paths
couldno longer be available.
NOTE 2
Refer to Desnerck et al, 'Inspection of RC half-joint bridges in England, ....' ICE (BE) 171 [Ref 6.I] for
guidance on defect types, potential effects in combination and risks associated with half-joints.
Structural risk
4.6
The risk rating for the structural risk RD , shall be determined based upon either:
1) the as built reinforcement detailing of the half-joint RD1 ; or,
2) the previous structural assessment findings specific to the half-joint RD2 .
NOTE 1
RD1 represents the risk of structural failure based on the indicative load carrying capacity estimated
from the adequacy of the as built reinforcement detailing evaluated in accordance with CS 455 [Ref
12.N].
NOTE 2
The indicative load carrying capacity of the half-joint can be estimated using the following
reinforcement detailing related aspects:
1) bar arrangement;
2) anchorage;
3) continuity of reinforcement ;
4) bearing stresses.
NOTE 3
RD2 represents the risk of structural failure based on the assessed load carrying capacity.
NOTE 4
The assessed load carrying capacity can be obtained from previous assessment findings in
assessment reports or certificates if available.
4.6.1
The as-built reinforcement detailing may be established through review of record information such as:
1) as-built drawings, construction records and other as-built information;
2) previous investigation or assessment reports;
3) previous structural assessments.
4.6.2
Where there is a lack of record information to determine RD , recommendation on whether
investigations are required to determine the as built reinforcement detailing should be included in the
risk management report.
4.6.3
Where there is a need to complete the risk assessment for a structure with lack of record information,
then a higher risk rating may be adopted for RD provisionally to reflect the lack of information.
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4. Risk assessment for structural assessment
Secondary risks
Consequential risk
4.7
The risk rating for consequential risk RQ , shall be determined based upon the current traffic and route
type over or under the structure.
NOTE 1
RQ represents the consequence of structural failure on the routes carried by or below the structure.
NOTE 2
Route types can include highways, railways, waterways, cycleways, bridleways, and footways.
4.7.1
RQ should be determined by evaluating the consequences of failure of the half-joint in terms of the
routes over and under the structure, including:
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
number of people killed or seriously injured;
damage to vehicles;
damage to utilities and services;
nature of the route over and under the structure;
the viability of diversion routes in the event of structural failure;
volume of traffic over and under the structure;
length of time to restore normal operation;
environmental pollution;
political and reputational damage; and,
financial impact.
Vulnerable details risk
4.8
The risk rating for the vulnerable details risk, RV shall be determined based upon additional vulnerable
details present on the structure.
NOTE
RV represents the risk of structural failure due to additional vulnerable details such as:
1)
2)
3)
4)
5)
post-tensioned elements;
evidence of inadequate drainage or waterproofing system;
low concrete grade;
sub-standard concrete cover;
presence of chlorides in concrete or grout.
Half-joint form risk
4.9
The risk rating for the half-joint form risk, RF shall be determined based upon the structural form of the
half-joint.
NOTE 1
RF represents the risk of structural failure due to the half-joint type which affects the ease of
accessibility and visibility for inspections and detecting defects.
NOTE 2
Examples of typical half-joint structural forms can be found in appendix C.
Other risks
4.10
The risk rating for other risks RO shall be taken as low unless agreed with the Overseeing Organisation.
4.10.1
RO may be determined based upon other considerations that affect the risk and priority of a structure.
NOTE 1
RO represents a tool to include other risks and considerations that could affect the priority of a half-joint
structure.
NOTE 2
Examples of other risks and considerations can include:
1) Overseeing Organisation preferences;
2) effects on, or caused by, new schemes such as changes to loading;
3) families of structures which have the same construction type.
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5. Structural review
5.
Structural review
5.1
Following the risk assessment for structural assessment, the structure shall be reviewed in accordance
with CS 451 [Ref 11.N] to determine if a new structural assessment is required.
5.1.1
The structural review should be undertaken in accordance with the priority list of half-joint structures
resulting from the risk assessment for structural assessment, starting with the highest priority structures
first.
5.2
Where the structural review finds the previous structural assessment is no longer valid then the risk
assessment for structural assessment shall be revisited to update the priority of the structure.
5.2.1
Where the structural review finds the previous structural assessment is no longer valid, RD1 may be
used in place of RD2 to update the priority of the structure.
NOTE
Examples of previous structural assessments that are no longer valid include the following:
1) the previous structural assessment did not specifically assess the capacity of the half joint;
2) an intrusive investigation finds reinforcement provision that does not match the as built records;
3) a change in the condition of the structure.
5.2.2
Where RD1 is used in place of RD2 following the structural review, the reason behind this should be
recorded in the risk management report.
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6.
6. Structural assessment
Structural assessment
Assessment processes and basis of assessment
6.1
The assessment processes and basis of assessment for the half joint shall follow the requirements of
CS 454 [Ref 1.N] and CS 455 [Ref 12.N] supplemented by the additional requirements of this section.
Limit states
6.2
The half-joint shall be assessed at the ULS.
6.3
Where an assessment of crack width at the SLS is proposed using calculations, the methodology shall
be recorded in the AIP.
NOTE
A simplified approach to crack width assessment at the SLS is provided in Appendix D.
Assessment actions and assessment action effects
6.4
The assessment actions and assessment action effects that are applied to the half-joint shall be
determined from an assessment of the structure in accordance with CS 455 [Ref 12.N] and CS 454
[Ref 1.N].
6.4.1
Where it is possible for longitudinal loading to be transmitted through the half-joint, for example due to a
seized bearing, the effects of longitudinal loading should be included.
Assessment of resistance
6.5
The assessment of resistance of the half-joint shall be carried out in accordance with CS 455 [Ref
12.N] and the additional requirements in this document, including the effects of:
1) poor detailing of reinforcement;
2) corrosion;
3) cracking and spalling;
4) reduced effectiveness of bond for bars with low cover or corroded bars;
5) reinforcement with low ductility; and,
6) reduced concrete resistances and bond due to internal degradation of concrete.
NOTE 1
Half-joint resistance can be particularly sensitive to the forces that can be developed in the reinforcing
bars within the half-joint, which depend on the detailing of the bars and the bond strengths that can be
developed.
NOTE 2
Common examples of poor detailing of reinforcement can include links that do not enclose the primary
tension reinforcement.
Verification
6.6
The value of γf 3 shall be obtained from CS 454 [Ref 1.N] based on the type of analysis used for the
assessment.
Methodology for structural analysis
6.7
The methodology for the structural analysis of the half-joint shall be recorded in the AIP for the
assessment.
6.8
A lower-bound analysis such as a strut-and-tie analysis shall be used to quantify the assessed
load-carrying capacity at the ULS, unless otherwise agreed with the Overseeing Organisation.
NOTE 1
Strut-and-tie or stress field analysis methods are based on the lower-bound theorem and therefore
generally provide a safe lower bound to the estimate of structural resistance at the ULS.
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6. Structural assessment
NOTE 2
Requirements for the use of strut-and-tie analysis for half-joint assessment are provided in this
document in the corresponding sub-section.
NOTE 3
Further guidance on stress field analysis is provided by Fernandez Ruiz & Muttoni A, 'On Development
of Suitable Stress Fields for Structural Concrete' Fernández Ruiz & Muttoni [Ref 8.I].
6.8.1
Additional analyses such as upper-bound mechanism analyses or non-linear finite element analyses
may be included in the ULS assessment to provide supplementary information regarding the
development of critical failure mechanisms and the assessment of structural risk.
NOTE 1
Mechanism analyses are based on the upper bound theorem and therefore generally provide an
unsafe upper bound to the estimate of structural resistance at the ultimate limit state.
NOTE 2
Requirements for the use of mechanism analyses and non-linear finite element analyses for half-joint
assessment are provided in this document in the corresponding sub-sections.
NOTE 3
A large difference between lower and upper-bound estimates of resistance indicates that there is scope
to improve the estimates by revising the models.
NOTE 4
A large difference between lower and upper-bound estimates of resistance can sometimes be
indicative of an unsafe upper-bound assessment.
6.9
For the assessment of wide half-joints with discrete bearings, the structural analysis methodology shall
be chosen to allow the forces in the horizontal lateral distribution reinforcement to be assessed.
NOTE 1
Structural analysis methodologies to assess the effects in 3 dimensions can include a 3D model or a
combination of 2D models in different planes with consistent boundary conditions.
NOTE 2
An example strut-and-tie model for a wide half-joint with discrete bearings is illustrated in Appendix E.
6.10
The vertical resistance of half-joints at the ultimate limit state shall not be assessed using structural
analysis models that rely on concrete in tension as a primary load carrying component.
Assessment based on strut-and-tie analysis
6.11
Where a strut-and-tie analysis is used, the assessment shall be carried out according to the
requirements for the strut-and-tie approach to the shear resistance of beams with shear reinforcement
in CS 455 [Ref 12.N] and the additional content in this document.
NOTE 1
The requirements in CS 455 [Ref 12.N] for the strut-and-tie approach to the shear resistance of beams
with shear reinforcement include limits on the stresses in struts, nodes and ties.
NOTE 2
The resistance estimated from lower-bound analyses (including strut-and-tie analyses) can often be
improved by adjustment of the model or using a more realistic model. Example strut-and-tie models for
half-joints and guidance on their application are provided in Appendix E.
NOTE 3
The strut-and-tie model can take a variety of forms, depending on many contributing factors including
the geometry, detailing of longitudinal reinforcement, presence of a diagonal bar, the structural
condition and the presence of post-tensioning.
6.11.1
Bonded pretensioning strand may be included in the resistance of ties in the same way as unstressed
reinforcement, with the limiting tensile resistance from yield or anchorage of the strands contributing to
the tensile resistance of the tie members.
6.11.2
Concrete tensile strength should not be included in the calculation of the tensile resistance of ties.
6.12
The forces in the struts and ties shall be in equilibrium with:
1) the externally applied assessment actions (e.g. the maximum forces applied to the half-joint);
2) the internal reaction forces at the interface between the region that is modelled using strut and tie
and the rest of the structure.
6.12.1
The effect of post-tensioning in half-joints may be modelled by applying the post-tensioning forces as
external actions at the anchor positions.
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6. Structural assessment
NOTE
For further guidance on the analysis of post-tensioned half-joints, see Appendix E.
6.12.2
Where the yield strength of prestressing steel is included in the tensile yield resistance of a tie member,
the prestressing force should not be simultaneously applied as an external action.
NOTE
Where prestressing force is included both as an external action and as part of the tensile resistance of
a tie, the prestressing effect can be unsafely double-counted.
6.12.3
For the strut-and-tie analysis of half-joints where some reinforcement is expected to yield before the
ultimate limit state is reached, and where the reinforcement in question has sufficient anchorage and
deformation capacity, the effects of plastic redistribution may be included to improve the assessed
resistance.
6.12.4
Methods for modelling the effects of plastic redistribution in strut-and-tie analysis to improve the
assessed resistance may include:
1) using statically indeterminate strut-and-tie models to control tie forces;
2) using superposition of complementary strut-and-tie systems;
3) using strut-and-tie models with wider struts (or struts that fan out radially) and larger nodes in order
to increase the number of reinforcement bars that are assumed to contribute simultaneously to a tie
at yield.
NOTE
For further guidance and examples of the methods for using plastic redistribution, see Appendix E.
Assessment based on mechanism analyses
6.13
Where a mechanism analysis is used, the analysis shall include the full range of possible compatible
failure mechanisms to identify the critical mechanism that provides the lowest estimate of resistance.
NOTE
Analysis of a non-critical mechanism results in an unsafe assessment of resistance. It is therefore very
important to optimise the analysis and include all possible mechanisms.
6.14
The upper-bound estimate of resistance shall be calculated as the minimum value of the applied
vertical load on the half-joint for which the work done by all the assessment loads in displacing a
mechanism is equal to the energy dissipated in displacing the mechanism, for any compatible
mechanism, as in Equation 6.14.
Equation 6.14 Limiting criterion for the upper bound estimate of resistance
W =E
where:
6.15
W
is the work done by the assessment loads
E
is the energy dissipated in displacing a mechanism
The critical mechanism shall be defined by:
1) the critical shape of the failure surface forming the discontinuity between the loaded part of the
half-joint and the part of the half-joint that is connected to the rest of the structure; and,
2) the critical relative displacement components (rotation, vertical and horizontal translation
components).
NOTE
A simple example mechanism is shown in Figure 6.15N. The positions of points A and B, the shape of
the discontinuity between A and B, and the components of displacement (δA , α, ϕA ) are all varied in the
analysis to find the critical mechanism. In many cases the critical mechanism can comprise a curved or
multilinear discontinuity instead of the straight discontinuity shown.
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6. Structural assessment
Figure 6.15N Simple example mechanism
6.15.1
The parts of the half-joint that are separated by the discontinuity should be considered to be rigid
bodies.
6.16
The work done by the assessment loads in the upper-bound mechanism analyses shall be determined
from Equation 6.16.
Equation 6.16 Work done by loads
W = γf 3
∑(
Q*ai .δi
)
where:
W
is the work done by the assessment loads
γf 3 is as defined in CS 454 [Ref 1.N] for upper bound mechanism analyses
Q*ai are the magnitudes of the assessment loads, including the respective partial factors for
actions, as defined in CS 454 [Ref 1.N]
δi are the components of the displacement for the mechanism being analysed, determined
at the points of application for each load in the direction of the applied load
NOTE
The assessment loads can include: the forces applied through the half-joint; post-tensioning forces
applied at the anchor positions; self-weight of the part of the half-joint up to the discontinuity position.
6.17
The energy dissipated in a mechanism shall be calculated from Equation 6.17.
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CS 466 Revision 0
6. Structural assessment
Equation 6.17 Energy dissipated in a mechanism
E=
∑
∫
Faj .δrj +
Ecl dx
where:
E
is the energy dissipated in the mechanism
Faj
are the assessment tension resistances that can be developed in each reinforcing bar or
bonded pre-tensioning strand crossing the discontinuity, determined at the position of the
discontinuity
δrj
are the relative displacements at the discontinuity for each reinforcing bar or
pre-tensioning strand, measured in the direction of the respective reinforcing bar or
pre-tensioning strand
Ecl
is energy dissipated in the concrete per unit length of discontinuity
x is the distance measured along the discontinuity
6.17.1
Where there is a sufficient anchorage detail beyond the discontinuity position in both directions for the
reinforcing bars or bonded pre-stressing steel to develop the assessment yield strength, the
assessment tension resistance Faj may be taken as the assessment yield strength according to CS
455 [Ref 12.N].
6.17.2
Where there is not a sufficient anchorage detail for the reinforcing bars or bonded prestressing steel to
develop the assessment yield strength at the discontinuity position, the assessment tension resistance
Faj should be limited to:
1) the residual post-slip anchorage resistance over the anchorage length from the discontinuity position
to the end of the bar, for straight reinforcing bars or prestressing strand; and,
2) the tension corresponding to the bearing stress in a hook or bend reaching its ultimate resistance,
for bent or hooked bars.
6.17.3
The residual post-slip anchorage resistance of a straight, deformed bar should be taken as:
1) equal to the anchorage resistance determined from CS 455 [Ref 12.N] where the cover to the bar is
greater than 5 bar diameters and the clear spacing between bars is greater than 10 bar diameters
and there is not an existing longitudinal crack aligned with the bar;
2) 0.4 times the anchorage resistance determined from CS 455 [Ref 12.N] where 1) does not apply and
the bar is enclosed by links; or,
3) zero where 1) does not apply and the bar is not enclosed by links.
NOTE 1
For further guidance, refer to FIB Model Code [Ref 3.I].
NOTE 2
A sudden reduction in bond strength can occur at a small value of displacement where a splitting failure
mode is critical, as in 2) and 3). In cases where a pull-out failure mode is critical, displacement can
occur at the peak bond resistance, as in 1).
6.17.4
The residual post-slip anchorage resistance of a straight plain bar or prestressing strand should be
taken as:
1) equal to the anchorage resistance determined from CS 455 [Ref 12.N] where there is not an existing
longitudinal crack aligned with the bar or strand;
2) 0.4 times the anchorage resistance determined from CS 455 [Ref 12.N] where there is an existing
longitudinal crack aligned with the bar or strand.
6.17.5
The anchorage resistance of bent or hooked bars should be determined from the limiting force to cause
bearing failure in the bend or hook as calculated using CS 455 [Ref 12.N].
6.17.6
The energy dissipated in the concrete per unit length of discontinuity should be calculated based on
Equation 6.17.6.
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CS 466 Revision 0
6. Structural assessment
Equation 6.17.6 Energy dissipated in the concrete per unit length of discontinuity
1 fcu
Ecl = ν
ub(1 − sin α)
2 γmc
where:
Ecl
ν
is the energy dissipated in the concrete per unit length of discontinuity
is the effectiveness factor for concrete
fcu is the characteristic concrete cube strength or worst credible concrete cube strength as
defined in CS 455 [Ref 12.N]
γmc is the partial factor for concrete strength as defined in CS 455 [Ref 12.N]
u is the magnitude of the relative displacement vector at the discontinuity as illustrated in
Figure 6.17.6
b is the breadth of the member
α is the angle of the relative displacement vector measured relative to the discontinuity as
illustrated in Figure 6.17.6
Figure 6.17.6 Definition of relative displacment at the concrete discontinuity
NOTE
Further guidance is provided in Nielsen and Hoang 2010 [Ref 7.I].
6.17.7
The effectiveness factor for concrete ν should be taken as 0.16 for structures that have crack widths in
service that do not exceed 1mm.
6.17.8
For structures with crack widths exceeding 1mm in service, the sensitivity of the resistance should be
assessed based on cautious values of ν less than 0.16.
NOTE
It is conservative to assume a value of ν = 0 .
Non-linear finite element analysis
6.18
Non-linear analysis shall fulfil the requirements given in of CS 455 [Ref 12.N].
NOTE
The structural analysis section of CS 455 [Ref 12.N] includes requirements for non-linear analysis
relating to the assessment of cracking - this is particularly important in half-joints where the vertical
resistance after cracking can be significantly lower than before cracking, and where the probability of
cracks arising from a variety of potential sources can be impossible to predict reliably.
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7. Risk assessment for management
7.
Risk assessment for management
7.1
A risk assessment shall be completed to prioritise structures with half-joints for management and
interventions.
7.2
The risk assessment for management shall be completed as per Section 4 of this document, with the
risk ratings updated where required.
Primary risks
Condition risk
7.3
The risk rating for the condition risk RC shall be reviewed to determine if the risk rating assigned is still
valid.
7.3.1
The validity of the risk rating for RC should be verified based upon:
1) findings from the most recent inspection; and,
2) any recent structure events reported which could affect the condition, for examples:
a) spalling concrete around the half-joint;
b) further cracking;
c) vehicle impact to the structure.
7.4
Where appropriate, RC shall be updated to reflect the current condition of the structure.
NOTE
Changes in the condition of a structure could affect the validity of the previous CS 451 [Ref 11.N]
structural review and previous structural assessments.
Structural risk
7.5
Where RD1 was used in the risk assessment for structural assessment to determine the structural risk
rating, this shall be replaced by RD2 to reflect the half-joint structural assessment findings.
7.6
The risk rating for the structural risk RD2 , shall be determined based upon the most recent and valid
structural assessment findings.
NOTE
Where RD2 was used in the risk assessment for structural assessment and there was no new structural
assessment required, then in the risk assessment for management, the risk rating for RD2 remains
unchanged.
Secondary risks
7.7
Where secondary risks were used in the risk assessment for structural assessment, they shall be
reviewed to determine whether the risk ratings are still valid or whether they need to be updated in the
risk assessment for management.
NOTE
Examples where the risk ratings for secondary risks need to be updated include:
1) implementation of new schemes which could affect the structure;
2) changes to traffic volumes;
3) changes to diversion route viability;
4) changes to the nature of the route.
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8. Management plan
8.
Management plan
8.1
The management plan for the half-joint structure shall be developed and recorded within the risk
management report.
8.1.1
The management plan should take into account the conclusions and recommendations from the
structural assessment report.
8.1.2
The management plan may comprise a summary of another report or study, where various options are
discussed and agreed.
8.2
The management plan shall be a live document, updated following changes to or arising from
management measures.
NOTE
Changes to or arising from management measures can include:
1) recommendations made to undertake investigations, inspections, assessments or studies;
2) recommendations arising from investigations, inspections, structural assessments or studies for
management measures to be implemented;
3) updates to management plan following implementation of management measures.
8.3
To determine an appropriate management plan, the structures shall be categorised into one of the
following categories:
1) structures assessed to have sufficient capacity;
2) structures assessed to have sufficient capacity but with concerns;
3) sub-standard structures.
NOTE 1
Structures assessed to have sufficient capacity are structures which pass their half-joint specific
structural assessment specific for its current condition.
NOTE 2
Structures assessed to have 'sufficient capacity but with concerns' are structures which pass their
half-joint specific structural assessment for its current condition but do so with condition concerns that
could be detrimental to the structural capacity over time.
NOTE 3
Sub-standard structures are structures that do not pass their structural assessment.
NOTE 4
Structural assessment results can be found in the structure assessment report.
Structures assessed to have sufficient capacity
8.4
A management plan shall be developed for structures assessed to have sufficient capacity.
8.4.1
The management plan should be targeted at maintaining or improving the current condition of the
structure such that:
1) the assumptions made for the structural assessment remain valid; and,
2) its assessed structural capacity does not deteriorate.
8.4.2
The management plan for structures assessed to have sufficient capacity should include the following
measures:
1) maintenance inspection regime to CS 450 [Ref 6.N]; and,
2) recommendations for maintenance activities.
Structures assessed to have sufficient capacity but with concerns
8.5
A management plan shall be developed for structures assessed to have sufficient capacity but with
concerns.
8.5.1
The management plan should be targeted at maintaining or improving the current condition of the
structure such that:
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CS 466 Revision 0
8. Management plan
1) the condition concerns are addressed;
2) the assumptions made for the structural assessment remain valid; and,
3) its assessed structural capacity does not deteriorate.
8.5.2
Structures assessed to have sufficient capacity but with concerns may be managed using the following
measures:
1) maintenance inspection regime to CS 450 [Ref 6.N];
2) recommendations for maintenance activities;
3) monitoring regime;
4) plan for interim measures;
5) long term solution.
Sub-standard structures
8.6
The management plan for sub-standard half-joint structures shall record the following:
1) the interim measures for managing the sub-standard structure according to CS 470 [Ref 9.N]; and,
2) long term management measures.
8.6.1
The management plan may record the interim measures for managing the sub-standard structure
according to CS 470 [Ref 9.N] by either:
1) including references to the documents and records required by CS 470 [Ref 9.N] ; or,
2) including a summary of the interim measures for managing the sub-standard structure according to
CS 470 [Ref 9.N] .
8.6.2
Half-joint structures assessed to be sub-standard may be managed using the following measures:
1) interim measures;
2) monitoring regime;
3) investigations;
4) repair;
5) strengthen;
6) replace;
7) other measures.
NOTE
For half joint structures, interim measures can be found in CS 470 [Ref 9.N].
Management measures
Maintenance inspections
8.7
An appropriate inspection regime shall be developed and recorded in the management plan.
NOTE 1
The Inspection Manual for Highway Structures IMHS V1 [Ref 5.I] provides guidance on undertaking
inspections of highway structures in general.
NOTE 2
Refer to Desnrerck P et al, 'Inspection of RC half-joint bridges in England, ....' ICE (BE) 171 [Ref 6.I] for
guidance on inspections specific to half-joint structures.
NOTE 3
Refer to CIRIA C764 [Ref 5.N], CS 455 [Ref 12.N], CS 450 [Ref 6.N] for guidance on the inspection and
assessment of half joints.
8.8
Where special inspections in accordance with CS 450 [Ref 6.N] are agreed with the Overseeing
Organisation as an appropriate management measure for a half-joint structure, the management plan
shall record a summary of the purpose and frequency of the special inspections.
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8.8.1
8. Management plan
Special inspections for half-joints should be carried out to determine:
1) presence and extents of expansion joint failure and consequent leakage of water and chlorides on
the half joint;
2) presence and extent of cracking at re-entrant corners;
3) presence and extents of efflorescence or any corrosion deposits;
4) presence and extents of concrete delamination or spalling; and,
5) bridge temperature at the time of the special inspection.
Maintenance activities
8.9
Recommended maintenance activities targeted at maintaining or improving the current condition of the
half-joint shall be recorded in the management plan.
NOTE
Effective maintenance activities for preventing further deterioration to a structure with half-joints can
include:
1) expansion joint replacement;
2) deck waterproofing repairs or replacement;
3) provision of effective drainage systems.
8.10
The timescales and intervals for the recommended maintenance activities to be implemented shall be
recorded in the management plan.
Monitoring
8.11
Where monitoring of a half-joint structure assessed to have sufficient capacity but with concerns is
agreed as an appropriate management measure with the Overseeing Organisation, the management
plan shall record a summary of the monitoring regime.
8.11.1
The management plan may record a summary of the monitoring regime by either:
1) including a reference of the monitoring specification; or,
2) including a summary of the monitoring specification such as:
a)
b)
c)
d)
NOTE
monitoring type;
monitoring frequency;
definition of trigger levels;
action plan if trigger levels are exceeded.
See CS 470 [Ref 9.N] for requirements and guidance on monitoring.
Plan for interim measures
8.12
For a structure assessed to have sufficient capacity but with concerns, the management plan shall
record a plan for suitable interim measures to be implemented in the event the condition of the
structure deteriorates such that it becomes sub-standard.
NOTE
The plan for interim measures is intended to present in advance suitable interim measures that could be
implemented in the event the condition of the structure deteriorates such that it becomes sub-standard.
Long term solutions
8.13
For a structure assessed to have sufficient capacity but with concerns, the management plan shall
record proposed long term solutions for the structure.
8.13.1
Long term solutions may include:
1) repair;
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CS 466 Revision 0
8. Management plan
2) strengthen;
3) replace.
Interim measures
8.14
For sub-standard structures the interim measures shall be implemented in accordance with CS 470
[Ref 9.N].
Investigations
8.15
Where investigations, either non-destructive testing or invasive investigations, have been agreed with
the Overseeing Organisation as an appropriate management measure for a sub-standard half-joint
structure, a summary of the details of the investigation shall be recorded in the management plan.
NOTE 1
Investigations are useful for obtaining further information on the condition of the structure, enabling
other management measures to be developed and targeted at addressing specific issues associated
with the half-joint.
NOTE 2
Non-destructive testing is preferred over invasive investigations to the structure as the former is unlikely
to compromise the structural capacity of the half-joint structure.
NOTE 3
Examples of investigations include:
1)
2)
3)
4)
5)
6)
7)
8)
8.16
chloride content testing;
cement content testing;
half-cell measurements;
impact echo testing;
radiography;
acoustic emission testing;
thermography;
borescope inspection of bars from small holes drilled to the reinforcement.
Invasive investigations shall be planned and implemented such that the structural integrity of the
half-joint structure is not compromised.
Repair
8.17
Where repairs have been agreed with the Overseeing Organisation as an appropriate management
measure for a sub-standard half-joint structure, a summary of the repair details and extents shall be
recorded in the management plan.
8.17.1
Repairs may include the following:
1)
2)
3)
4)
5)
concrete repairs;
reinforcement replacement;
cathodic protection;
chloride extraction;
active moisture reduction systems.
NOTE
Refer to CD 370 [Ref 2.N] for requirements and guidance on cathodic protection systems.
8.18
Concrete repairs shall be implemented in accordance with CD 359 [Ref 3.N].
8.19
Proposed repair solutions shall be targeted at reducing the risk rating for the structure.
Strengthening
8.20
Where strengthening has been agreed with the Overseeing Organisation as an appropriate
management measure for a sub-standard half-joint structure, a summary of the agreed strengthening
proposals shall be recorded in the management plan.
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CS 466 Revision 0
8. Management plan
8.21
Proposed strengthening measures shall be targeted at reducing the risk rating for the structure or
eliminating the half-joint detail.
NOTE
Possible strengthening measures for half-joint structures include:
1) provision of additional supports;
2) installing additional reinforcement in the half-joint;
3) structurally connect the supporting span with the drop-in span to eliminate the half-joint detail.
8.22
Where strengthening works have been implemented to eliminate the half-joint detail on a structure, the
structure shall be removed from the risk management process in this document as it is no longer a
half-joint structure.
Replacement
8.23
Where replacement of the half-joint structure has been agreed with the Overseeing Organisation as an
appropriate management measure for a sub-standard half-joint structure, a summary of the agreed
replacement proposals shall be recorded in the management plan.
8.23.1
Replacement of the half-joint structure should be proposed where half-joints have deteriorated so badly
that the half-joint is practically and economically beyond repair or strengthening.
NOTE
An example of half joint deterioration requiring replacement can be where the corrosion of the
reinforcement is so extensive, it cannot be effectively replaced in order to improve the structural
capacity of the half-joint structure.
8.23.2
Replacement of a half-joint structure should be targeted at eliminating the half-joint details.
NOTE
It is not always possible for a replacement structure to eliminate the half-joint details due to site and
operational constraints, for example, site constraints can dictate that the support spans with the half
joint detail are retained, and only the drop-in span replaced.
8.24
Where the half-joint details are retained, replacement solutions shall be targeted at reducing the risk
rating for the half-joint structure.
8.25
Where replacement works have been implemented to eliminate the half-joint detail on a structure, the
structure shall be removed from the risk management process in this document as it is no longer a
half-joint structure.
31
CS 466 Revision 0
9.
9. Normative references
Normative references
The following documents, in whole or in part, are normative references for this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
Ref 1.N
Highways England. CS 454, 'Assessment of highway bridges and structures'
Ref 2.N
Highways England. CD 370, 'Cathodic protection for use in reinforced concrete
structures.'
Ref 3.N
Highways England. CD 359, 'Design requirements for permanent soffit formwork'
Ref 4.N
BSI. BS EN 1992-2, 'Eurocode 2. Design of concrete structures. Part 2: Concrete
bridges. Design and detailing rules'
Ref 5.N
CIRIA. Collins J et al. CIRIA C764, 'Hidden defects in bridges. Guidance for detection
and maintenance'
Ref 6.N
Highways England. CS 450, 'Inspection of highway structures'
Ref 7.N
Highways England. GG 101, 'Introduction to the Design Manual for Roads and
Bridges'
Ref 8.N
CIRIA. CIRIA C778, 'Management of safety critical fixings in-service. Guidance for
the management and design of safety-critical fixings'
Ref 9.N
Highways England. CS 470, 'Management of sub-standard highway structures'
Ref 10.N
Highways England. GG 104, 'Requirements for safety risk assessment'
Ref 11.N
Highways England. CS 451, 'Structural review and assessment of highway structures'
Ref 12.N
Highways England. CS 455, 'The assessment of concrete highway bridges and
structures'
32
CS 466 Revision 0
10.
10. Informative references
Informative references
The following documents are informative references for this document and provide supporting
information.
Ref 1.I
TRL. Clark, LA & Thorogood P. TRL CR70, 'Contractor Report 70, 'Serviceability
Behaviour of Reinforced Concrete Half-Joints''
Ref 2.I
BSI. BS EN 1992, 'Eurocode 2. Design of concrete structures'
Ref 3.I
FIB - Fédération Internationale du Béton, 2010. The International Federation for
Structural Concrete (FIB). FIB Model Code, 'FIB - Model Code for Concrete
Structures'
Ref 4.I
ACI. ACI 201.1 R-92, 'Guide for making a condition survey of concrete in sevice'
Ref 5.I
TSO. IMHS V1, 'Inspection Manual for Highway Structures. Volume 1: Reference
Manual'
Ref 6.I
ICE Publishing. Desnerck P, Lees JM, Valerio P, Loudon N, Morley CT. ICE (BE) 171,
'Inspection of RC half-joint bridges in England: analysis of current practice,
Proceedings of the Institution of Civil Engineers, Bridge Engineering 171, July 2018,
p290-302''
Ref 7.I
CRC Press, 2010. Nielsen M, Hoang L. Nielsen and Hoang 2010, 'Limit analysis and
concrete plasticity'
Ref 8.I
ACI Structural Journal, July / August 2007. M Fernández Ruiz and A Muttoni.
Fernández Ruiz & Muttoni, 'On Development of Suitable Stress Fields for Structural
Concrete'
Ref 9.I
BSI. PD 6688-1-7, 'Recommendations for the design of structures to BS EN 1991-1-7'
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Appendix A. Half-joint terminology
Appendix A. Half-joint terminology
Figure A.1 shows the terminology used to describe elements of the half-joint.
Figure A.1 Half-joint terminolgy
34
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Appendix B. Model documents
Appendix B. Model documents
This appendix provides models for the risk management report and priority list.
B1
Model risk management report
A model risk management report is shown in Table B.1.
Table B.1 Model risk management report
Structure information
This should include the following information:
1) structure name;
2) structure reference;
3) structure location;
4) brief description of the structure;
5) form of the half-joint;
6) summary of the current condition of the structure.
Initial review
This should include the following information:
1) inputs (reference for documents used in the initial review);
2) findings from initial review;
3) where applicable, reference to sub-standard structure management documents.
Risk assessment for structural assessment
This should include the following information:
1) primary risks (including evidence and output);
2) primary risk rating;
3) secondary risks (including evidence and output);
4) where applicable, refined primary risk rating from use of secondary risks;
5) where applicable, secondary risk rating.
Summary of structural review findings
This should include a statement summarising the findings from the structural review agreed with the
TAA (e.g. whether a new structural assessment specific to the half-joint is required).
Summary of structural assessment findings
This should include the following information:
1) assessed capacity of the half-joint from the assessment and check certificates accepted by the
TAA; and,
2) summary of recommendations from the structural assessment report agreed with the TAA.
Risk assessment for management
35
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Appendix B. Model documents
Table B.1 Model risk management report (continued)
This section should include the following information, with risk ratings reviewed and updated where
applicable:
1) primary risks (including evidence and output);
2) primary risk rating;
3) secondary risks (including evidence and output);
4) where applicable, refined primary risk rating from use of secondary risks; and,
5) where applicable, secondary risk rating.
Management plan
This section may include the following information
1) management measures;
2) recommendations from investigations, studies and reports;
3) references to reports and relevant documents;
4) where applicable, record of CS 470 [Ref 9.N] measures.
B2
Model priority list
A model priority list for a group of structures is shown in Table B.2. This can be used for the priority for
assessment and the priority for management.
36
Priority
Structure
name
Structure
reference
Primary
risk rating
Primary Refined primary
risk rating(1)
risks
Secondary
risk rating (2)
Secondary
risks
Risk management
report reference
Current status/
comments
1
2
CS 466 Revision 0
Table B.2 Model priority list
3
4
5
Note (1): Refined primary risk rating is applicable when secondary risks are used to increase the primary risk rating.
Note (2): Secondary risk rating is applicable when secondary risks are used to prioritise between a number of structures with the same primary risk rating.
37
Appendix B. Model documents
CS 466 Revision 0
Appendix C. Guidance on risk assessment
Appendix C. Guidance on risk assessment
C1
General
This appendix provides illustrative example processes that can be used for risk assessment of half-joint
structures, using the primary and secondary risks described in this document.
The basis of the illustrative example risk assessment processes presented within this Appendix is as
follow:
1) primary risks RC and RD used to determine a primary risk rating;
2) the severity of the consequences at this stage is taken as being very high;
3) secondary risks RQ , RV , RF , RO may be used to either:
a) increase the primary risk rating, resulting in the refined primary risk rating; or,
b) prioritise within a group of structures with the same primary risk rating, resulting in the secondary
risk rating.
Where secondary risks are used to increase the primary risk rating, this is referred to as the refined
primary risk rating. For example if bridge A and bridge B both have a high risk rating from the matrix in
Table C.1, but bridge A is on a strategic route over a major railway (so RQ is very high), then the risk
rating for bridge A can be increased from high to very high.
Where secondary risks are used to prioritise between a number of structures with the same primary risk
rating, this is referred to as the secondary risk rating. For example if bridge C and bridge D both have
very high risk rating from the matrix in Table C.1, but bridge C is on a strategic route over a major
railway (so RQ is very high), then bridge C can be prioritised over bridge D.
C2
Primary risk rating
The primary risk rating for an individual structure can be determined from the matrix Table C.1 below
using condition and structural risks.
Table C.1 Matrix for determining primary risk rating of a half-joint structure
Structural risk RD
Condition
risk RC
RD Very
high
RD High
RD Medium
RD Low
RC Very high
Very high (1)
Very high (1)
High (1)
High (1)
RC High
Very high (1)
High (1)
High (1)
Medium (1)
RC Medium
High (1)
High (1)
Medium (1)
Medium (1)
RC Low
High (1)
Medium (1)
Medium (1)
Low (1)
Note (1) = The primary risk rating determined from the combination of RC and RD .
C2.1
Condition risk
The condition risk rating RC can be determined using the steps below:
1) use the latest valid inspection information to collate half-joint defects;
2) identify each defect using the inspection photographs and the defect decision diagram in Figure C.1
which is adapted from ICE (BE) 171 [Ref 6.I]. Additional guidance on defect types can be found in
ACI 201.1 R-92 [Ref 4.I] and IMHS V1 [Ref 5.I];
3) record the location of each defect using the zones defined in Figure C.2 taken from ICE (BE) 171
[Ref 6.I]. This can also be used to locate reinforcement detailing deficiencies for structural risk;
4) determine the damage rating for each defect. Table C.2 provides guidance and uses information
taken from ICE (BE) 171 [Ref 6.I]; and,
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Appendix C. Guidance on risk assessment
5) when all defects are recorded, consider in combination, their location and the damage to assign a
risk level from Table C.4.
39
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Figure C.1 Defects decision diagram
40
Appendix C. Guidance on risk assessment
CS 466 Revision 0
Figure C.2 Zones within the half joint to record locations of condition and detailing defects
41
Appendix C. Guidance on risk assessment
CS 466 Revision 0
Appendix C. Guidance on risk assessment
In Figure C.2, hn is the partial height of the nib and c is the reinforcing bar cover. Where cover cannot
be ascertained, c should be assumed to be 40mm.
Table C.2 Damage rating
Damage
Very slight
Slight
Moderate
Severe
Very severe
Cracks in
prestressed
concrete
width <0.05
mm
width 0.05-0
.1mm
width 0.1-0.3mm
width 0.3-1.
0mm
width 1-3mm with
some spalling
Cracks in
reinforced
concrete
width <0.1m
m
width 0.1-0.
3mm
width 0.3-1.0mm
width 1-3m
m with some
spalling
width >5mm with
widespread spalling
heavy rust
stains
heavy rust stains
and cracking
along line of bar
heavy rust
stains and
spalling
along line of
bars
heavy rust stains
and spalling along
line of bars, in more
than one location or
for a number of
bars.
clean water
seepage to
large areas
of the joint.
water seepage
with discolouration
at edge
beam/footpath
locations
30-70% of
joint with
discolouration
gritted road/
coastal
environment
affecting >70% of
joint with
discolouration with
signs of historic
presence.
gritted road/coastal
environment
area up to 150x 15
0mm across
area larger
than 150 x 1
50mm
multiple areas >250
x 250mm;
single areas more
than 1000 x 1000m
m
Effects of
reinforcement
corrosion
light rust
stains
Joint
leakage/
water
staining
clean/clear
water, small
patches of
dampness
Spalling/
delamination (1)
cover <50x5
0mm
100x100mm
Note (1) - The size of a concrete spall should be compared to relative to the size of the half joint. The
criteria is for guidance purposes and is not prescriptive.
42
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Appendix C. Guidance on risk assessment
Table C.3 Guidance for condition risk
Risk rating
Example of risk rating
Examples include:
1) more than a single very severe condition defect in the same zones and
likely to work in combination such that there are not alternative load paths;
Immediate risk(1)
2) more than a single very severe condition defect not in the same zone but
which may reduce the number of load paths;
3) single very severe condition defect.
Examples include:
1) more than a single severe condition defect in the same zones and likely to
work in combination such that there are not alternative load paths;
Very high
2) more than a single severe condition defect not in the same zone but which
may reduce the number of available load paths;
3) single severe condition defect.
Examples include:
1) more than a single moderate condition defect in the same zones and likely
to work in combination such that alternative load paths may not be available;
High
2) more than a single moderate condition defect not in the same zone but
which may reduce alternative load paths;
3) single moderate condition defect.
Examples include:
Medium
1) more than a single slight condition defects in the same zones or likely to
work in combination.
Examples include:
Low
1) slight or very slight condition defects, or when in combination, are not
significant;
2) single or very slight condition defect.
Note (1) - this provides examples of situations where a half-joint structure can be considered as an
immediate risk structure in accordance with CS 470 [Ref 9.N]. This examples given is not an
exhaustive list.
An example table format for recording the information required to assign a risk rating is shown in Table
C.4 below.
Table C.4 Example table for recording defect information
Defect description
from data
Data
reference
Defect
identification
Zone
Damage
rating
Defects in
combination
Where it is not possible to accurately record a defect type, for example cracked concrete with no signs
43
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Appendix C. Guidance on risk assessment
of corrosion, then the information that is apparent from the inspection data should be recorded.
Where it is not possible to determine the zone of the defect within the half joint, as shown in Figure C.2,
from the inspection data, (for example where rust staining is visible to the soffit) then the location from
where the defect is visible should be recorded and the lack of visibility should contribute to the risk
rating assigned.
Defective detailing can increase the impact of condition defects and thus the risk level.
C2.2
Structural risk
C2.2.1
Structural risk RD1
The structural risk rating RD1 can be determined using the steps below:
1) estimate from the arrangement of the reinforcement, the available load paths through the half joint
evaluated in accordance with CS 455 [Ref 12.N];
2) evaluate the following reinforcement detailing related aspects:
a)
b)
c)
d)
bar arrangement;
anchorage;
continuity of reinforcement; and,
bearing stresses;
3) use Table C.5 to assign a risk rating for detailing; and,
4) evaluate the combination of effects from condition and detailing deficiencies by recording locations
using the zones in Figure C.2. The combination of effects can be used when assigning a primary
risk rating from Table C.1.
44
Detailing risk
rating
Description and illustrative examples - typical detailing
Detailing shows no clear load path through half-joint or critically poor anchorage. It appears probable that the detailing is insufficient to prevent a
failure mechanism from developing.
Poor detailing of nib bar
& diagonal bar
Poor detailing of nib bar
and links
Poor detailing of nib bar,
light area of links
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Table C.5 Detailing risk rating
No information
Very
high
Load path through the structure affected by poor detailing/anchorage.
45
Diagonal bar not
anchored
Nib bar not anchored
Links not anchored
Links not anchored
Very short length
High
Well-anchored but no
diagonal bar
Medium
Post-tensioned, no
diagonal bar
Appendix C. Guidance on risk assessment
Detailing allows a single clear load path through the half-joint with adequate anchorage.
Detailing allows multiple load paths through half-joints, through the combination of complementary systems of well-anchored bars.
Well-anchored, with
diagonal bar and links
Post-tensioned, with
diagonal bar and links
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Table C.5 Detailing risk rating (continued)
Low
46
Appendix C. Guidance on risk assessment
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Appendix C. Guidance on risk assessment
The combination of effects from condition and detailing deficiencies should be assessed by recording
locations using the zones shown in Figure C.2. The combination of effects can be used when assigning
a primary risk rating from Table C.1.
C2.2.2
Structural risk RD2
The structural risk rating RD2 can be determined from Table C.6 using the assessed structural capacity.
Table C.6 Guidance for structural risk from assessed capacity
Risk rating
Examples of risk rating
Examples:
Very high
1) structure requires propping;
2) structure assessed to be able to carry dead load only.
Examples:
High
1) load restrictions required on carriageway.
Examples:
Medium
1) assessed capacity greater than 40t on elements supporting the carriageways but
reduced capacities on the edge beam/ footpath.
Examples:
Low
1) assessed capacity greater than 40t ALL throughout the structure.
Where there is a need to complete the risk assessment for a structure with lack of record information,
then a higher risk rating may be adopted provisionally to reflect the lack of information.
C3
Secondary risks
C3.1
Consequential risk
The consequential risk RQ can be determined using the method detailed below:
1) use Table C.7 (derived from CIRIA C778 [Ref 8.N]) to select consequential risk scores;
2) add together the risk scores to determine the total score Q for the structure;
3) use Table C.8 for Q scoring bands to assign a consequential risk level.
47
Very High
High
Medium
Low
Score Q
10
3
1
0
Number of people
killed or seriously
injured
Potential for 1 or more people
to be killed or seriously injured.
Potential for slight injuries to
five or more people.
Potential for slight injuries to
fewer than five people.
No potential for injuries or other
harm to health.
Potential for severe damage to
one or more:
Potential for minor damage to
one or more:
1) road vehicles;
1) road vehicles;
2) trains; or,
2) trains; or,
3) floating vessels.
3) floating vessels.
Any of the following:
Any of the following:
Any of the following:
Any of the following:
1) potential for any disruption
to one or more nationally
and regionally important
utility services;
1) potential for severe
disruption to a single locally
important utility service;
1) potential for moderate
disruption to a single locally
important utility service;
2) potential for moderate
disruption to one or more
locally important utility
service; or,
2) potential for minor disruption
to one or more locally
important utility service; or,
1) no potential for disruption to
nationally and regionally or
locally important utility
service;
Potential damage
vehicles
48
3) potential for moderate
disruption to more than one
locally important utility
service.
3) potential for severe
disruption to other utility
services.
Potential for minor damage to
single:
1) road vehicles;
No damage sustained
2) trains; or,
3) floating vessels.
3) potential for moderate
disruption to one or more
other utility service.
2) potential for minor disruption
to one or more other utility
service;
3) potential for moderate
disruption to a single locally
important utility service;
4) potential for minor disruption
to one or more locally
important utility service; or,
5) potential for moderate
disruption to one or more
other utility service.
Appendix C. Guidance on risk assessment
Potential damage
to utilities and other
public or private
services
2) potential for severe
disruption to one or more
locally important utility
services; or,
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Table C.7 Consequential risks
Nature of route
Any of the following:
Any of the following:
Any of the following:
1) strategic route;
1) A road/principal road;
1) B/C road;
2) motorway;
2) city centre footpath;
2) urban commuter cycle-path;
1) unclassified road;
3) trunk road;
3) cycle superhighway;
3) town centre footpath; or,
2) accommodation road;
4) Network Rail route criticality
band 1 or 2;
4) Network Rail route criticality
band 3 or 4;
4) Network Rail route criticality
band 5.
3) rural cycle path;
5) mass transit urban railway;
or,
5) freight only line; or,
4) rural footpath/right of
way/bridleway; or,
6) leisure waterway.
5) other waterway.
Any of the following:
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Table C.7 Consequential risks (continued)
6) commercial waterway.
Any of the following:
1) no viable pedestrian or
vehicular diversion route
exists;
49
2) no alternative route exists
for rail, waterway or utility;
Diversion route
3) rural diversion route >10
miles;
4) urban diversion route >5
miles;
Any of the following:
Any of the following:
1) one alternative rail,
waterway or utility route
exists;
1) multiple alternative rail,
waterway or utility route
exists;
1) rural diversion route ≤ 1
mile;
2) rural diversion route >5
miles and ≤ 10 miles;
2) rural diversion route >1 mile
and ≤ 5 miles;
3) urban diversion route ≥ 2
miles and ≤ 5 miles; or,
3) urban diversion route >0.5
miles and ≤ 2 miles; or,
4) pedestrian diversion route >
0.5 miles and ≤ 1mile.
4) pedestrian diversion route >
0.25 miles and ≤ 0.5 miles.
2) urban diversion route ≤ 0.5
miles; or,
3) pedestrian diversion route ≤
0.25 miles.
Appendix C. Guidance on risk assessment
5) pedestrian diversion route
>1 mile.
Any of the following:
Very heavy traffic flow:
1) highway: >70,000
vehicles/day;
2) Network Rail: >6
trains/hour;
3) mass transit urban rail: >10
trains/hour;
Volume of traffic
4) commercial waterway: >10
vessels/hour;
5) leisure waterway: >20
vessels/hour;
6) pedestrian only: heavily
used in accordance with
PD 6688-1-7 [Ref 9.I].
50
Length of time to
restore normal
network operation
1) highway: >20,000 and ≤ 70
,000 vehicles/day;
2) Network Rail: >3 and ≤ 6
trains/hour;
3) mass transit urban rail: >5
and ≤ 10 trains/hour;
4) commercial waterway: >5
and ≤ 10 vessels/hour;
5) leisure waterway: >10 and
≤ 20 vessels/hour;
6) pedestrian only: generally
used in accordance with PD
6688-1-7 [Ref 9.I].
Low traffic flow:
Very low traffic flow:
1) highway: >5,000 and ≤ 20,0
00 vehicles/day;
1) highway: ≤ 5,000
vehicles/day;
2) Network Rail: >1 and ≤ 3
trains/hour;
2) Network Rail: ≤ 1
train/hour;
3) mass transit urban rail: >2
and ≤ 5 trains/hour;
3) mass transit urban rail: ≤ 2
trains/hour;
4) commercial waterway: >2
and ≤ 5 vessels/hour;
4) commercial waterway: ≤ 2
vessels/hour;
5) leisure waterway: >5 and ≤
10 vessels/hour;
5) leisure waterway: ≤ 5
vessels/hour;
6) pedestrian only: lightly used
in accordance with PD
6688-1-7 [Ref 9.I]
6) pedestrian only: rarely used
in accordance with PD
6688-1-7 [Ref 9.I].
>1 month
>1 week and ≤ 1 month
>1 day and ≤ 1week
≤ 1 day
Major pollution incident, for
example:
Moderate pollution incident, for
example:
Low pollution incident:
No pollution
1) widespread pollution to
major watercourses;
2) affects fisheries or other
commercial activities;
1) high volume of contaminant
contained within the
boundaries of the site, e.g.
within holding tanks;
3) results in evacuation of
premises located off site;
2) results in evacuation of the
on-site premises only; or,
4) required removal of
contaminated land or other
material; or,
3) does not affect neighbouring
land owners/occupiers.
1) localised incident that can
be dealt with by a one or
two man crew; and,
2) does not result in
contamination of
watercourse or land.
5) affects neighbouring land
owners/occupiers.
Political and
reputation damage
Very high
National media coverage
High
Regional media coverage
Low
Local media coverage
Very low
No media coverage
Appendix C. Guidance on risk assessment
Potential
environmental
pollution
High traffic flow:
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Table C.7 Consequential risks (continued)
Financial impact
Very high
High
Low
Very low
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Table C.7 Consequential risks (continued)
51
Appendix C. Guidance on risk assessment
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Appendix C. Guidance on risk assessment
Table C.8 Consequential risk rating
Risk
rating
Total score Q
from
Table C.7
Example of risk rating
Examples:
Very high
45 ≤ Q < 100
1) potential for one or more people to be killed or seriously
injured;
2) closure of route of strategic importance, no acceptable
diversion;
3) very heavy traffic flow etc.
Examples:
High
15 ≤ Q < 45
1) potential for slight injuries to five or more people;
2) principal or A road, high traffic flow route etc.
Examples:
Medium
5 ≤ Q < 15
1) potential for slight injuries to fewer than five people;
2) B/C road, low traffic flow, etc.
Examples:
Low
Q<5
1) no potential for injuries or other harm to health;
2) very low traffic flow;
3) unclassified road etc.
C3.2
Vulnerable details risk
The risk rating for the vulnerable details risk, RV can be determined using Table C.9 below:
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Appendix C. Guidance on risk assessment
Table C.9 Vulnerable details risk ratings
Risk rating
Example of risk rating
Examples:
1) single vulnerable detail with significant issues;
Very high
2) multiple vulnerable details with defects or significant defects;
3) no information.
Examples:
High
1) single vulnerable detail with issues or defects.
Examples:
Medium
1) multiple vulnerable details but without defects or issues.
Examples:
Low
1) no other vulnerable details or a single other detail without defects or issues.
C3.3
Half-joint form risk
The risk rating for the half-joint form, RF can be determined from the process below:
1) select a half-joint type from Figures C.3, joints of unknown type should be assumed as type A;
2) score the joint type from Table C.10;
3) score the ease of access from Table C.11; and,
4) select the half-joint form risk rating from Table C.12, which is determined by adding the score from
Table C.10 and Table C.11.
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Appendix C. Guidance on risk assessment
Figure C.3 Half-joint types
Table C.10 Score for joint detail
Joint detail
Score
A solid or box slab with no access to the bearing shelf
7
B concrete solid slab with restricted access to the the bearing shelf
5
C precast beam and slab with individual beams and access to areas of the bearing shelf
3
D composite deck with individual beams/ girders and access to areas of the bearing shelf
2
Table C.11 Ease of access
Ease of access to half-joint level
Score
Difficult to access more than one joint
2
Difficult to access one joint
1
Moderate
0
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Appendix C. Guidance on risk assessment
Table C.12 Half-joint form risk
Risk
rating
C3.4
Example of risk rating
Very high
x≥8
Type A with difficult access to joint from below for 1 or more joint see
scoring on half-joint type
High
6≤x≤7
Type A, Type B with difficult access to joint from below for more than
1 joint
Medium
x=5
Type B, Type B with difficult access to joint from below for 1 joint,
Type C with difficult access to more than 1 joint
Low
x≤4
Type C, Type C with difficult access to joint from below for 1 joint,
Type D
Other risks
The risk rating for other risks, RO can be determined based upon the Table C.13 below:
Table C.13 Other risks
Risk rating
Example of risk rating
Examples:
Very high
1) structure is within forthcoming scheme limits;
2) structure is part of strategic development of the highway network;
3) structure is within a family of structures known to suffer from significant defects.
Examples:
1) structure is near to a forthcoming scheme;
High
2) structure is near a strategic development site;
3) structure is within a family of structures known to suffer defects.
Examples:
Medium
1) structure is within a family of structures that have been targeted for interventions.
Examples:
Low
1) no other factors that will effect the risk of the structure;
2) no other issues allow for grouping of the structure.
55
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Appendix D. Simplified method for SLS assessment of half-...
Appendix D. Simplified method for SLS assessment of half-joints
D1
Simplified analysis for calculation of crack widths in half-joints
This appendix includes a simplified informative method for calculating crack widths in reinforced
concrete half-joints where the cracking is assumed to initiate at the re-entrant corner and extend at 45
degrees into the structure. For further guidance, see TRL Report TRL CR70 [Ref 1.I].
Figure D.1 Assumed strain distribution
Figure D.2 Crack width model
The assumed strain distribution at the serviceability limit state is illustrated in Figure D.1. The maximum
56
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Appendix D. Simplified method for SLS assessment of half-...
concrete tensile strain is assumed to occur at the re-entrant corner (point B) and the maximum
compressive strain is assumed to occur at point A vertically above the line of intersection of the neutral
axis of the nib part of the half-joint with a line at 45 degrees from the re-entrant corner. The strain
distribution in the tensile zone is non-linear as a result of slip occurring between the reinforcement and
the concrete.
The compressive strain in the concrete and the tensile strain in the reinforcement may be determined
directly from an elastic analysis, but with some modification of the extreme fibre concrete tensile strain.
The crack width may be calculated as the lesser of the values from Equations D.1 and D.2:
Equation D.1 Crack width 1
w=
√
2(a − 0.5y)ϵm
Equation D.2 Crack width 2
w = 3acr ϵm
where:
w
is the crack width
a
is the distance of the vertical reaction taken at the front edge of a rigid bearing or centre
line of a flexible bearing from the re-entrant corner
y
is the dimension of the fillet
acr
is the distance from the nearest bar to the point where the crack width is calculated
ϵm
is the mean strain taking account of slip and the tension stiffening effect, which can be
taken from Equation D.3
Equation D.3 Mean strain
ϵm = K1 ϵ1 − K2 bh
fctm
Es ϵs As
where:
K1
is taken as 2.3 when inclined reinforcement is present, and 3.5 where inclined bars are
omitted
ϵ1
is the strain at the re-entrant corner as calculated from an elastic analysis
K2
is taken as 0.003
b
is the breadth of the half-joint
h
is the depth of the half-joint
fctm
is the mean tensile strength of the concrete (see BS EN 1992-2 [Ref 4.N])
Es
is the elastic modulus of steel reinforcement
ϵs
is the strain at the steel level in the direction normal to a 45 degree line from the re-entrant
corner, determined from an elastic analysis.
As
is the effective area of steel normal to a 45 degree crack from the re-entrant corner,
determined from Equation D.4
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Appendix D. Simplified method for SLS assessment of half-...
Equation D.4 Effective area of steel
As = ΣAsi cos2 (45 − βi )
where:
Asi
is the area of one layer of reinforcement at an angle bi to the horizontal.
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Appendix E. Illustrative examples of strut-and-tie models...
Appendix E. Illustrative examples of strut-and-tie models of half joints
E1
General
This appendix includes illustrative examples of strut-and-tie models for typical features that can be
encountered when assessing half-joints, including:
1) presence of post-tensioning;
2) detailing of horizontal nib reinforcement;
3) bent-up diagonal reinforcement;
4) corrosion or spalling;
5) longitudinal reinforcement not enclosed by links;
6) loads applied through discrete bearings;
7) transition from solid half-joint to discrete beam webs.
This appendix also includes illustrative examples of strut-and-tie models that enable analysis of plastic
redistribution in half-joints, including:
1) using statically indeterminate models to control tie forces;
2) using superposition of complementary strut-and-tie systems;
3) using strut-and-tie models with wider struts and nodes.
The examples given illustrate possible approaches, but other strut-and-tie arrangements may be used.
The geometry and layout of the strut-and-tie models should be developed to suit the features of the
particular half-joint being assessed.
In the figures in this appendix, the centre-lines of struts are shown as dashed lines and ties are shown
as solid lines.
E2
Illustrative examples of strut-and-tie models for typical features of half-joints
E2.1
Presence of post-tensioning
Where post-tensioning is present in a half-joint, the strut-and-tie model should be developed to satisfy
equilibrium with the applied post tensioning actions at the anchor points, as in the example shown in
Figure E.1.
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.1 Example of strut-and-tie model for a half-joint with post-tensioning
For the example of Figure E.1, the post tensioning is sufficient to avoid any horizontal tension ties.
Where the loading is sufficient to induce some tension, the strut and tie model should be adjusted to
include one or more ties. An example is shown in Figure E.2.
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.2 Example of strut-and-tie model for a half-joint with post-tensioning with
tie to resist tension in the nib.
E2.2
Detailing of horizontal nib reinforcement
The detailing of the horizontal nib reinforcement can have a large effect on the assessed resistance,
particularly because of the following effects that can reduce the effectiveness of half-joints with a short
nib reinforcement length:
1) the force that can be developed in the nib reinforcement can be limited by anchorage; and,
2) the demand on the first rank of vertical steel can be greater than if there is a long nib reinforcement
length.
Examples of strut-and-tie models for half-joints with long and short nib reinforcement details are given
in Figure E.3 and Figure E.4.
The position of node X in Figure E.3 and Figure E.4 should be chosen to allow a sufficient anchorage
length beyond X for the force in the horizontal nib tie to be developed.
Strut XY is not needed for equilibrium, but its presence gives the model some statical indeterminacy,
which can be useful in controlling how much of the load is taken in each vertical tie (see E3.1). If strut
XY is not included, the angles should be chosen to satisfy θ1 ≥ θ2 otherwise some of the struts could go
into tension.
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.3 Illustrative example of strut-and-tie model for a half-joint with long nib
reinforcement
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.4 Illustrative example of strut-and-tie model for a half-joint with short nib
reinforcement
In some half-joint arrangements with short nib reinforcement it can be possible for part of the load to be
resisted using the vertical steel beyond the nib reinforcement anchorage point, as illustrated in Figure
E.5, thereby reducing the demand on the first rank of vertical steel. The relative strut angles in the
model can affect whether the struts remain in compression, and therefore whether such an approach is
effective.
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.5 Illustrative example of strut-and-tie model for a half-joint with a short nib
anchorage, using vertical steel beyond the nib reinforcement anchor point
E2.3
Bent-up diagonal reinforcement
Where the half-joint contains a diagonal bar that is bent upwards, the strut-and-tie model should be
developed to suit the arrangement of the tension bars, as illustrated in Figures E.6 and E.7.
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.6 Example strut-and-tie model for a half-joint with a bent-up diagonal bar
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.7 Example strut-and-tie model for a half-joint with a bent-up diagonal bar
E2.4
Corrosion or spalling
Half-joints can be vulnerable to corrosion, and in some cases this can lead to section loss, spalling of
concrete and loss of bond. The effects of corrosion and reduced cover on anchorage bond resistance
are covered in CS 455 [Ref 12.N]. In some cases, the corroded bars can be incapable of providing the
tie resistance that is needed according to the strut-and tie analysis. Where the tie force can not be
resisted by the surface reinforcement, the strut and tie model should be adjusted to avoid relying on the
affected bars. An example could be that the bottom layer of reinforcement is exposed due to spalled
concrete cover, and the bars have insufficient bond to develop the tension in the bottom horizontal tie.
In this case the possibility of using higher layers of reinforcement or prestressing strand to provide a tie
force at a higher level should be investigated, as illustrated in Figure E.8.
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.8 Adjusted strut-and-tie model to avoid relying on the bottom layer of
reinforcement.
E2.5
Longitudinal reinforcement not enclosed by links
Longitudinal reinforcement that is not enclosed by links should not be included in the longitudinal tie
resistance if the tie is assumed to be connected to the vertical ties via nodes. In order for the forces to
be effectively transmitted from the vertical ties to the horizontal ties, there needs to be an effective
anchorage between the two, usually provided by enclosing the longitudinal reinforcement in links.
Where the bottom layers of reinforcement are not enclosed by links, the strut-and-tie model should be
adjusted so that the forces can be effectively transmitted through the nodes. For example, the position
of the bottom tie may be raised to align with the reinforcement or prestressing strand that is effectively
enclosed by links, using a similar approach to that used for corroded bottom steel in Figure E.8.
E2.6
Loads applied through discrete bearings
Where loads are applied through discrete bearings, the loads may be distributed laterally according to
the approach illustrated in Figures E.9 and E.10. The end view in Figure E.10 illustrates how the lateral
tie forces associated with the lateral distribution can be analysed.
According to this model, the longitudinal reinforcement at the top of the nib is effective when it is
located directly under the bearing, as illustrated in Figure E.9 and E.10, and so the bars in the top of the
nib that lie between the bearings should not be included in the resistance of the horizontal tie.
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.9 Loads applied through discrete bearings - side view
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.10 Loads applied through discrete bearings - end view
E2.7
Transition from solid half-joint to discrete beam webs
For cases where a solid, wide half-joint transitions to a discrete beam, the struts extending into the
beam web should be proportioned to fit within the beam web. However, if the loads are applied along
the width of the half joint then the lateral distribution may be modelled used an approach similar to that
illustrated in Figures E.11 and E.12 (the example is shown for a half-joint with a system of diagonal
bars).
69
CS 466 Revision 0
Appendix E. Illustrative examples of strut-and-tie models...
Figure E.11 Transition from solid half-joint to discrete beam webs - side view
70
CS 466 Revision 0
Appendix E. Illustrative examples of strut-and-tie models...
Figure E.12 Transition from solid half-joint to discrete beam webs - end view
E3
Illustrative examples of strut-and-tie models enabling analysis of plastic
redistribution in half-joints
E3.1
Using statically indeterminate models to control tie forces
Strut-and-tie models that have a degree of statical indeterminacy can be used to control the tension in
a critical tie so that it does not exceed the yield force. The process is illustrated in Figure E.13 (for an
example with a long length of nib reinforcement) and Figure E.14 (for an example with a short length of
nib reinforcement). In both examples, it is the first vertical tie that is expected to yield first, and this
reinforcement has sufficient ductility and anchorage to justify using redistribution. By replacing the
critical tie in the model with a pair of internal forces equal to the assessment yield resistance, the model
may be reanalysed to determine the redistributed forces in the other ties and struts.
71
CS 466 Revision 0
Appendix E. Illustrative examples of strut-and-tie models...
Figure E.13 Example of a strut-and-tie model where the critical tie in a statically
indeterminate model has been replaced by a pair of internal forces (for a half-joint
with a long length of nib reinforcement)
72
CS 466 Revision 0
Appendix E. Illustrative examples of strut-and-tie models...
Figure E.14 Example of a strut-and-tie model where the critical tie in a statically
indeterminate model has been replaced by a pair of internal forces (for a half-joint
with a short length of nib reinforcement)
E3.2
Using superposition of complementary strut-and-tie systems
Superposition of strut-and-tie models can enable two complementary systems to be analysed and
combined, where there is sufficient ductility and anchorage in the critical ties for each system. An
example of this approach is illustrated in Figures E.15, E.16 and E.17. The resistances for the two
systems can be calculated. Then the two systems can be superposed to give a combined resistance.
However, the combined system should also be checked to ensure that:
1) the reinforcing bars are not being double counted by contributing to ties in both systems;
2) the struts in the combined system have sufficient resistance for the combined strut forces (e.g.
where a strut is present in both systems, like the bottom strut in Figure E.17).
73
CS 466 Revision 0
Appendix E. Illustrative examples of strut-and-tie models...
Figure E.15 Illustrative example of a strut-and-tie model for a system with diagonal
bars
74
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.16 Illustrative example of a strut-and-tie model for a system with vertical
bars
75
CS 466 Revision 0
Appendix E. Illustrative examples of strut-and-tie models...
Figure E.17 Illustrative example of superposition of systems of diagonal and
vertical bars
E3.3
Using strut-and-tie models with wider struts and nodes.
In cases where the resistance of a strut and tie model is limited by a tie, it can be possible to increase
the assessed resistance by including a greater number of reinforcing bars in the critical tie. Where the
bars in question have sufficient ductility and anchorage, the number of bars that contribute can
sometimes be increased if there is space to increase the size of the connecting nodes (and the
associated struts). An example is illustrated in Figures E.18 and E.19, where by increasing the size of
the struts and nodes it is possible to justify a larger number of bars contributing to the vertical tie, and
therefore increase the assessed resistance.
76
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.18 Example of a strut-and-tie model with narrow nodes and struts
77
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Appendix E. Illustrative examples of strut-and-tie models...
Figure E.19 Example of a strut-and-tie model with wider nodes and struts to enable
a greater number of reinforcing bars to be included in the critical tie.
78
© Crown copyright 2020.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
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write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
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Design Manual for Roads and Bridges
Highway Structures & Bridges
Inspection & Assessment
CS 466
England National Application Annex to CS 466
Risk management and structural assessment
of concrete half-joint deck structures
(formerly IAN 53/04 and BA 39/93)
Revision 0
Summary
This National Application Annex gives the Highways England-specific requirements which
enables the safety and serviceability of half-joints to be managed and assessed, providing key
information that is required to manage risks and maintain a safe and operational network.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage
of this document to the dedicated Highways England team. The email address for all enquiries and feedback is:
Standards_Enquiries@highwaysengland.co.uk
This is a controlled document.
CS 466 Revision 0
Contents
Contents
Release notes
2
Foreword
Publishing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contractual and legal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
3
3
Introduction
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assumptions made in the preparation of this document . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
4
4
Abbreviations
5
E/1. AMS NSP Activities
AMS NSP activities . . . . . . . . . . . . . . .
Inspection of half-joint structures . . . . . . . .
Initial visual inspection . . . . . . . . . . .
Detailed inspection . . . . . . . . . . . . .
Further inspection . . . . . . . . . . . . .
Structural assessment . . . . . . . . . . . . .
Invasive inspection and non-destructive testing
Future management . . . . . . . . . . . . . . .
Monitoring . . . . . . . . . . . . . . . . . . . .
Monitoring . . . . . . . . . . . . . . . . . .
Monitoring management . . . . . . . . . .
Interim measures . . . . . . . . . . . . . . . . .
Interim measures appraisal . . . . . . . .
Interim measures implementation . . . . .
Interim measures management . . . . . .
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6
6
8
8
8
8
8
8
9
9
9
9
9
10
10
10
E/2. Normative references
11
Appendix E/A. Links between NSP activities and half-joint structures risk management process
E/A1 Map of NSP activities to the half-joint risk management process . . . . . . . . . . . . . . . . . . . . .
12
12
1
CS 466 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Mar 2020
Highways England National Application Annex to CS 466.
2
CS 466 Revision 0
Foreword
Foreword
Publishing information
This document is published by Highways England.
This document supersedes IAN 53/04 and BA 39/93, which are withdrawn.
Contractual and legal considerations
This document forms part of the works specification. It does not purport to include all the necessary
provisions of a contract. Users are responsible for applying all appropriate documents applicable to
their contract.
3
CS 466 Revision 0
Introduction
Introduction
Background
This National Application Annex (NAA) gives the Highways England specific requirements related to
the risk management and structural assessment of half-joint structures. This NAA describes the
requirements for the Asset Management System (AMS) national structures programme (NSP) activities
in relation to concrete half-joint deck structures.
Assumptions made in the preparation of this document
The assumptions made in GG 101 [Ref 2.N] apply to this document.
4
CS 466 Revision 0
Abbreviations
Abbreviations
Abbreviations
Abbreviation
Definition
AMS
Asset management system
NAA
National Application Annex
NSP
National structures programme module of the AMS
5
CS 466 Revision 0
E/1.
E/1. AMS NSP Activities
AMS NSP Activities
AMS NSP activities
E/1.1
The AMS NSP module shall be used to capture data and organise a series of activities for the concrete
half-joint structures programme.
NOTE 1
The NSP activities are shown in the flowchart in Figure E/1.1N1.
6
CS 466 Revision 0
E/1. AMS NSP Activities
Figure E/1.1N1 AMS NSP activities flowchart for structures with half-joints
NOTE 2
The links between the NSP activities and the half-joint structure risk management process are shown in
Appendix E/A.
7
CS 466 Revision 0
E/1. AMS NSP Activities
NOTE 3
The processes for interim measures are described in CS 470 [Ref 3.N].
E/1.2
Information related to the planning, implementation and outputs from the NSP activities shall be
recorded in the AMS.
Inspection of half-joint structures
Initial visual inspection
E/1.3
The initial visual inspection shall be targeted at providing an initial evaluation of the condition of the
half-joint.
E/1.3.1
Where previous inspections of the half-joint structure are unavailable or a change in condition is likely
since the structure was last inspected, then an initial visual inspection of the half-joint should be
undertaken, following agreement with Highways England.
E/1.3.2
The initial visual inspection should determine the severity and location of any defects in the vicinity of
the half-joint.
E/1.3.3
Access requirements for a detailed inspection should be determined during the initial visual inspection.
Detailed inspection
E/1.4
The detailed inspection shall be targeted at providing a detailed evaluation of the condition of the
half-joint and quantify defects to inform the structural assessment.
E/1.4.1
Where previous inspections of the half-joint structure are unavailable or a change in condition is likely
since the structure was last inspected, then a detailed inspection of the half-joint should be undertaken,
following agreement with Highways England.
E/1.4.2
The detailed inspection may be undertaken in conjunction with the initial inspection.
Further inspection
E/1.5
Further inspection of the half-joint shall be undertaken where significant defects to or in the vicinity of
the half-joint are found.
E/1.5.1
The further inspection may consist of the following activities:
1) small exposure of reinforcement;
2) concrete testing;
3) concrete sampling.
NOTE 1
Small exposure of reinforcement typically involves drilling small holes to the reinforcement and
inspecting using a borescope.
NOTE 2
Concrete testing typically includes half-cell measurement, chloride content, cement content etc.
E/1.5.2
The further inspection may be undertaken in conjunction with the detailed inspection and/or the initial
visual inspection.
Structural assessment
E/1.6
The objectives of the half-joint structural assessment shall include the following:
1) to determine risks to the structural integrity of the half-joint;
2) to identify deterioration trigger points for feeding into the management plan; and,
3) to help identify likely future risk management measures.
Invasive inspection and non-destructive testing
E/1.7
Where the half-joint structural assessment recommends obtaining additional structural information on
the half-joint and this is agreed by Highways England, then invasive inspections and non-destructive
testing shall be undertaken.
8
CS 466 Revision 0
E/1. AMS NSP Activities
Future management
E/1.8
Where the structural assessment concludes that the structure is assessed to have sufficient capacity,
then no special actions shall be required apart from maintenance inspection and maintenance activities.
NOTE
Maintenance inspections are covered in CS 450 [Ref 1.N].
Monitoring
Monitoring
E/1.9
Where the half-joint structural assessment findings recommends periodic monitoring or inspections and
this is agreed by Highways England, then a regime of periodic monitoring and/or inspections shall be
implemented.
NOTE 1
See CS 470 [Ref 3.N] for requirements and guidance on monitoring.
NOTE 2
Pending the implementation of a long term solution, monitoring can be a suitable short- term solution to
mitigate risks for half-joint structures with concerns about the serviceability and strength of the half-joint
such as:
1) significant defects found to or in the vicinity of the half-joint;
2) structural assessment finds that the structural capacity is marginally greater than the assessment
actions, but further deterioration will result in reducing the structural capacity below the assessment
actions.
E/1.10
Monitoring shall be targeted at measurable critical parameters.
E/1.10.1
For half-joint structures, monitoring parameters may include:
1) horizontal movement at the joint;
2) vertical movement at the joint;
3) movement due to traffic actions;
4) crack widths;
5) deflections;
6) strains;
7) material deterioration.
Monitoring management
E/1.11
Monitoring shall be managed to ensure that:
1) monitoring is targeted at measurable critical parameters;
2) monitoring trigger levels are defined prior to implementation; and,
3) monitoring duration and intervals are defined prior to implementation.
E/1.11.1
The monitoring duration should be reviewed periodically, taking into account any changes in condition
of the structure.
E/1.12
Where monitoring trigger levels are exceeded, then monitoring trigger actions in accordance with the
monitoring specification shall be implemented.
NOTE
Guidance for monitoring specification is given in CS 470 [Ref 3.N].
E/1.13
Where the monitoring and inspection findings results in a new review trigger for a half-joint structure,
the risk management process shall be revisited for that structure.
9
CS 466 Revision 0
E/1. AMS NSP Activities
Interim measures
Interim measures appraisal
E/1.14
Where the half-joint structural assessment concludes that the structure is sub-standard, an appraisal of
interim measures in accordance with CS 470 [Ref 3.N] to evaluate risks, options and timescales shall
be undertaken.
Interim measures implementation
E/1.15
Once the options for interim measures have been agreed, the interim measures shall be implemented
in accordance with CS 470 [Ref 3.N].
E/1.16
Confirmation of the implementation of interim measures for the structure shall be recorded in the AMS.
Interim measures management
E/1.17
Interim measures shall be managed to ensure they remain effective in mitigating risks to the road
network throughout their service life in accordance with CS 470 [Ref 3.N].
10
CS 466 Revision 0
E/2.
E/2. Normative references
Normative references
The following documents, in whole or in part, are normative references for this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
Ref 1.N
Highways England. CS 450, 'Inspection of highway structures'
Ref 2.N
Highways England. GG 101, 'Introduction to the Design Manual for Roads and
Bridges'
Ref 3.N
Highways England. CS 470, 'Management of sub-standard highway structures'
11
CS 466 Revision 0
Appendix E/A. Links between NSP activities and half-joint s...
Appendix E/A. Links between NSP activities and half-joint structures risk
management process
E/A1
Map of NSP activities to the half-joint risk management process
Figure E/A.1 maps the NSP activities to the corresponding stages of the half-joint structures risk
assessment and risk management process.
12
CS 466 Revision 0
Appendix E/A. Links between NSP activities and half-joint s...
Figure E/A.1 Map of NSP activities to the half-joint structures risk management
process
13
© Crown copyright 2020.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.
Design Manual for Roads and Bridges
Highway Structures & Bridges
Inspection & Assessment
CS 466
Northern Ireland National Application Annex to
CS 466 Risk management and structural
assessment of concrete half-joint deck
structures
(formerly IAN 53/04 and BA 39/93)
Revision 0
Summary
This National Application Annex gives the Department for Infrastructure Northern Ireland specific
requirements for risk management and structural assessment of concrete half-joint deck
structures.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage of
this document to the dedicated team in the Department for Infrastructure, Northern Ireland. The email address for all
enquiries and feedback is: dcu@infrastructure-ni.gov.uk
This is a controlled document.
CS 466 Revision 0
Contents
Contents
Release notes
2
Foreword
Publishing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Contractual and legal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
3
3
Introduction
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assumptions made in the preparation of this document . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
4
4
NI/1. Applicability
5
NI/2. Normative references
6
1
CS 466 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Mar 2020
Department for Infrastructure Northern Ireland National Application Annex to
CS 466.
2
CS 466 Revision 0
Foreword
Foreword
Publishing information
This document is published by Highways England on behalf of Department for Infrastructure, Northern
Ireland.
This document supersedes IAN 53/04 and BA 39/93, which are withdrawn.
Contractual and legal considerations
This document forms part of the works specification. It does not purport to include all the necessary
provisions of a contract. Users are responsible for applying all appropriate documents applicable to
their contract.
3
CS 466 Revision 0
Introduction
Introduction
Background
This National Application Annex gives the Department for Infrastructure Northern Ireland specific
requirements for risk management and structural assessment of concrete half-joint deck structures.
Assumptions made in the preparation of this document
The assumptions made in GG 101 [Ref 1.N] apply to this document.
4
CS 466 Revision 0
NI/1. Applicability
NI/1.
Applicability
NI/1.1
In Northern Ireland the process of risk management and structural assessment of concrete half-joint
deck structures shall be in accordance with Department for Infrastructure Policy.
5
CS 466 Revision 0
NI/2.
NI/2. Normative references
Normative references
The following documents, in whole or in part, are normative references for this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
Ref 1.N
Highways England. GG 101, 'Introduction to the Design Manual for Roads and
Bridges'
6
© Crown copyright 2020.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.
Design Manual for Roads and Bridges
Highway Structures & Bridges
Inspection & Assessment
CS 466
Scotland National Application Annex to CS
466 Risk management and structural
assessment of concrete half-joint deck
structures
(formerly IAN 53/04 and BA 39/93)
Revision 0
Summary
There are no specific requirements for Transport Scotland supplementary or alternative to those
given in CS 466.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage
of this document to the dedicated Transport Scotland team. The email address for all enquiries and feedback is:
TSStandardsBranch@transport.gov.scot
This is a controlled document.
CS 466 Revision 0
Contents
Contents
Release notes
2
1
CS 466 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Mar 2020
Transport Scotland National Application Annex to CS 466.
2
© Crown copyright 2020.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.
Design Manual for Roads and Bridges
Highway Structures & Bridges
Inspection & Assessment
CS 466
Wales National Application Annex to CS 466
Risk management and structural assessment
of concrete half-joint deck structures
(formerly IAN 53/04 and BA 39/93)
Revision 0
Summary
There are no specific requirements for Welsh Government supplementary or alternative to those
given in CS 466.
Feedback and Enquiries
Users of this document are encouraged to raise any enquiries and/or provide feedback on the content and usage
of this document to the dedicated Welsh Government team. The email address for all enquiries and feedback is:
Standards_Feedback_and_Enquiries@gov.wales
This is a controlled document.
CS 466 Revision 0
Contents
Contents
Release notes
2
1
CS 466 Revision 0
Release notes
Release notes
Version
Date
Details of amendments
0
Mar 2020
Welsh Government National Application Annex to CS 466.
2
© Crown copyright 2020.
You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the
Open Government Licence. To view this licence:
visit www.nationalarchives.gov.uk/doc/open-government-licence/,
write to the Information Policy Team, The National Archives, Kew, London TW9 4DU,
or email psi@nationalarchives.gsi.gov.uk.