ISO 16311-2:2014

INTERNATIONAL ISO
STANDARD 16311-2
First edition
2014-04-15
Maintenance and repair of concrete
structures —
Part 2:
Assessment of existing concrete
structures
Entretien et réparation des structures en béton —
Partie 2: Évaluation des structures en béton existantes
Reference number
©
ISO 2014
© ISO 2014
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ii © ISO 2014 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Framework of assessment . 4
4.1 General . 4
4.2 Personnel . 4
4.3 Objectives of assessment . 6
4.4 Scenarios . 6
4.5 Preliminary and detailed assessment . 6
4.6 Reporting results of assessment .10
4.7 Judgement and decision .10
4.8 Intervention .10
5 Site and laboratory investigation and data collection .10
5.1 General .10
5.2 Planning and execution of inspection and data collection .10
5.3 Registration of condition .11
6 Evaluation and verification .13
6.1 Evaluation of action .13
6.2 Evaluation of materials and structural details .13
6.3 Verification of structural performance .15
6.4 Judgment .15
7 Recommendation .15
8 Report .16
Annex A (informative) Assessment levels, investigative tests, and examples of assessments .17
Annex B (informative) Condition and Consequence Levels .34
Annex C (informative) Evaluation and Verification .37
Annex D (informative) Recommendations .40
Annex E (informative) Content of the Final Report .42
Bibliography .44
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 71, Concrete, reinforced concrete and pre-stressed
concrete, Subcommittee SC 7, Maintenance and repair of concrete structures.
ISO 16311 consists of the following parts, under the general title Maintenance and repair of concrete
structures:
— Part 1: General Principles
— Part 2: Assessment of Existing Concrete Structures
— Part 3: Design of Repairs and Prevention
— Part 4: Execution of Repairs and Prevention
iv © ISO 2014 – All rights reserved

Introduction
Assessment of a concrete structure identifies and defines areas of distress, and verifies structural
performance based on the evaluated condition of the structure. It includes the whole process from
defining the work through the investigation, evaluation, verification, and registration to the final report.
This is necessary as a basis for the design of the repair and the preparation of procedures to preserve or
extend its remaining service life.
The report, concluding the assessment, includes a description of the structure, the investigation, the
results of condition assessment, the verified structural performance, the expected future development,
and a short presentation of possible repair principles and methods, including appropriate cost calculations.
A detailed planning and design of the repair work (repair or rehabilitation project specification) is not
part of the assessment, see ISO 16311-3.
This part of ISO 16311 gives the requirements for assessment of concrete structures, including a
framework for the assessment, a format for documentation of the condition assessment with assessed
condition level and consequence level, and a format for documentation of the performance assessment
with verified specific structural performance.
This part of ISO 16311 is operable with standards for test methods. Some standards for test methods
are under preparation by ISO but they will not all be available as International Standards at the date
of publication of this part of ISO 16311. Until and after such International Standards are available, a
national annex may list standards that have established suitability in the place of use of the methods.
These may be national standards or standards of other regions or nations.
This part of ISO 16311 is primarily based on the principles given in ISO 13822, Basis of design of structures
— Assessment of existing structures. Annex B in ISO 13822 has a detailed flowchart, included as Figure 1
in this part of ISO 16311.
INTERNATIONAL STANDARD ISO 16311-2:2014(E)
Maintenance and repair of concrete structures —
Part 2:
Assessment of existing concrete structures
1 Scope
This part of ISO 16311 describes general requirements and procedures for the assessment of concrete
structures.
The assessment can be initiated under the following circumstances, but not limited to:
a) an anticipated change in use or extension of design service life;
b) structural deterioration due to time-dependent actions such as corrosion of reinforcement, fatigue,
etc.;
c) safety and/or serviceability check (e.g. for earthquake and increased traffic actions) as required by
authorities, insurance companies, owners, etc.;
d) structural damage by accidental actions. (See ISO 2394.)
This part of ISO 16311 does not cover
— qualification of personnel,
— contractual matters, and
— health and safety requirements for the protection of workers during the investigation and testing.
2 Normative references
The following documents, in whole or in part, are normatively referenced in 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.
In the case of reference to International draft standards, provisions given in the National Annex or
project specification should be applied until the International Standard is available.
ISO 2394, General principles on reliability for structures
ISO 13822:2001, Bases for design of structures – Assessment of existing structures
ISO 16204, Durability — Service life design of concrete structures
ISO 16311-1, Maintenance and repair of concrete structures — Part 1: General principles
ISO 16311-3, Maintenance and repair of concrete structures — Part 3: Design of repairs and prevention
ISO 16311-4, Maintenance and repair of concrete structures — Part 4: Execution of repairs and prevention
ISO 19338, Performance and assessment requirements for design standards on structural concrete
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 16311-1, ISO 2394, ISO 13822,
and ISO 19338 and the following apply:
3.1
accidental action
action that is unlikely to occur with a significant value on a given structure over a given reference period
Note 1 to entry: Accidental actions are in most cases of short duration.
[SOURCE: ISO 2394:1998]
3.2
action, direct
assembly of concentrated or distributed mechanical forces acting on a structure
3.3
assessment
set of activities performed in order to verify the reliability of an existing structure for future use
[SOURCE: ISO 13822:2010]
3.4
condition
status of a structure or a structural member at a given time
3.5
condition description
statement of the condition status and level based on condition registration of a structure or a structural
member
3.6
condition documentation
all information that explains the condition of a structure or a structural member
3.7
condition level
expression of the condition of a structure or a structural member, compared to a reference level
3.8
condition registration
survey and collection of information to define the condition of a structure or structural member
3.9
condition verification
comparison between condition and defined requirements
3.10
consequence level
expression of seriousness of consequences related to a defined reference level
3.11
damage
unfavourable change in the condition of a structure that can affect structural performance
[SOURCE: ISO 13822:2010]
2 © ISO 2014 – All rights reserved

3.12
defect
fault, or deviation from the intended level of performance of a structure or its parts
[SOURCE: ISO 15686-1:2000]
3.13
deterioration
process that adversely affects the structural performance, including reliability over time due to
— naturally occurring chemical, physical or biological actions,
— repeated actions such as those causing fatigue,
— normal or severe environmental influences,
— wear due to use, or
— improper operation and maintenance of the structure
[SOURCE: ISO 13822:2010]
3.14
environmental action
assembly of physical, chemical, or biological influence which may cause restraint effects or deterioration
to the materials making up the structure, which in turn may adversely affect its serviceability,
restorability, and safety
[SOURCE: ISO 13822:2001]
3.15
inspection
conformity evaluation by observation and judgement accompanied as appropriate by measurement,
testing or gauging
Note 1 to entry: For structures, this evaluation consists of actions collecting information on the current state
of a structure through observation and simplified non-destructive or destructive testing supplemented with
materials and structural testing, as required.
[SOURCE: ISO 9000:2005, 3.8.2]
3.16
risk
combination of the probability or frequency of occurrence of an event and the magnitude of its
consequences
[SOURCE: ISO 13824:2009]
3.17
symptom
indicator for the condition of a structure or structural member, based on one or more characteristics
3.18
visual inspection
inspection of a structure by visual observation in the preliminary investigation for its assessment
4 Framework of assessment
4.1 General
The overall assessment procedure shall comply with ISO 13822 and include the following main parts
according to Figure 1, which is a general flowchart copied from ISO 13822:
— objectives of assessment;
— scenarios;
— preliminary assessment;
— detailed assessment;
— reporting results of assessment;
— judgement and decision;
— intervention.
A site visit is recommended prior to initiating the assessment.
4.2 Personnel
An assessment shall be performed by qualified personnel.
NOTE A National Annex can include requirements on qualification for personnel.
4 © ISO 2014 – All rights reserved

Figure 1 — General flowchart for assessment of existing structures (adapted from ISO 13822,
Annex B)
4.3 Objectives of assessment
The objectives of the assessment of an existing concrete structure, in terms of its operable condition
and its future structural performance, shall be specified in consultation with the client (the owner, the
authority, insurance companies, etc.) based on the following performance levels:
a) safety performance level;
b) continued function performance level;
c) special performance requirements of the client.
NOTE Reference is made to ISO 13822, 4.1
The objectives of the assessment shall be determined or confirmed before starting the assessment
activities. Within the determined objectives of assessment, the assessment shall be carried out with the
procedure given in Figure 1.
The objectives of an assessment, the extent and the application of methods and resources shall be
defined in a project specification.
The extent of an assessment depends on the nature of the structure, if a rough cost estimate of
recommended actions shall be included, etc.
The content of an assessment shall be re-evaluated continuously based on the observations.
NOTE A.1 gives more detailed description of purpose and scope of a condition assessment.
4.4 Scenarios
One or some scenarios to represent a possible change in structural performance shall be specified prior
to the preparation of assessment to identify possible critical situations for the structure. These scenarios
shall be developed with an understanding of the type of construction, the timeframe of construction, and
the environment to which the structure or structural member were exposed. These scenarios include,
but are not limited to (see also 16311-3)
— chloride exposure, and damage related to chloride-induced corrosion,
— carbonation-induced corrosion damage,
— mechanical (impact, overload, settlement, vibration, seismic, abrasion, fatigue, explosion, etc),
— chemical (alkali-aggregate reactions, aggressive agents, biological actions, etc), and
— physical (fire, frost damage, thermal effects, shrinkage, erosion, wear, etc).
Possible scenarios shall be reviewed thoroughly before carrying out the assessment activities. Scenarios
shall be continuously checked during the assessment to identify possible
— critical situations for the structure, including structural safety and serviceability, and
— amendments of the layout of the assessment.
4.5 Preliminary and detailed assessment
4.5.1 Levels of assessment
The purpose and scope of the assessment is decisive for the level of assessment and the content of each
level. The assessment shall not be taken any further than what is necessary to reach a firm decision on
intervention to be taken.
6 © ISO 2014 – All rights reserved

Normally, the assessment is classified into two levels as follows.
a) Preliminary assessment (see 4.5.2): the aim is to provide information of the condition of the
structure, clarify causes for and seriousness of the deterioration, giving basis for indicating an overall
condition level, and a consequence level of the structure, including future safety and serviceability
of the structure. Possible immediate actions have to be decided. If necessary, a detailed assessment
shall be proposed.
b) Detailed assessment (see 4.5.3): the aim is in principle the same as for preliminary assessment, but a
more detailed study of previous documents, a more detailed inspection and material testing, as well
as structural analysis and verification, has to be carried out in order to make the correct judgement
and decisions.
NOTE 1 A.1 provides additional information regarding levels of assessment.
NOTE 2 A.2 provides details on condition registration, including current information from construction and
operation, observation on site, possible tests on site and in laboratory as well as a listing of symptoms and possible
causes for defects.
4.5.2 Preliminary assessment
4.5.2.1 Study of documents and other data
Design and inspection documents, such as original design, drawings, project specification, structural
calculations, as built documentation, previous assessments, and intervention, etc. provide important
information. For many existing structures, it may be difficult to find such information and to be sure
that the information is correct. Both structural requirements (e.g. service load, dead load, overload,
wind, snow, etc.), and environmental conditions (e.g. chlorides, gasses, temperature, etc.) shall be
documented, and if any changes have occurred. The use and possible misuse of the structure, compared
to the original design assumptions, shall be documented, if possible.
4.5.2.2 Preliminary inspection
The preliminary inspection is primarily a visual observation, in some cases supported with simple types
of testing at the structure (e.g. carbonation measurements). This inspection shall give information on
the structural system and if any surface characteristics are visible (e.g. reinforcement corrosion, cracks,
spalling, deformation etc.).
4.5.2.3 Preliminary checks
Based on the study of documents and other evidences, and the results of the preliminary inspection,
preliminary checks shall be performed. This is to identify the critical deficiencies related to the future
safety and serviceability of the structure or structural members. Such checks can be based on general
knowledge and experience, or by simple calculations.
The results of the preliminary inspection and checks shall be described by condition levels and
consequence levels.
The choice of an appropriate condition level shall be based on judgement of the observed symptoms
and the preliminary checks, and related to a reference level for the structure or a structural member.
Normally five condition levels are defined from “Good” to “Unsafe”.
NOTE 1 Annex B gives a more detailed description of the condition levels.
NOTE 2 Reference levels for different cause(s) for deterioration can be provided in a National Annex with a
picture catalogue based on symptoms.
The consequences of the observed condition and the preliminary checks for a structure or a structural
member, if nothing is done within a certain time, shall be described by consequence levels. The
consequence levels refer to the consequence for the structure itself, and are independent of the reliability
class of the structure, which shall also be recorded. Normally, five consequence levels are defined from
“No consequences” to “Potentially hazardous or (structurally) unsafe consequences”.
NOTE 3 Annex B gives more detailed description of consequence levels.
4.5.2.4 Decisions on immediate actions
When the results of the preliminary inspection and/or the checks shows that the structure is in a
dangerous condition, it has to be reported to the client that immediate interventions shall be taken
in order to reduce the dangerous situation with respect to safety of the general public, workers or
occupants, and adjacent structures. If the safety of a structure or structural member is not clearly
understood after the preliminary assessment, a detailed assessment shall be performed immediately to
assess the critical deficiencies, and if necessary, recommendations made to the client for intervention.
4.5.2.5 Recommendation for detailed assessment
When the preliminary inspection and checks clearly show that the consequences of any deficiencies
are very low and that the structure or structural members are reliable for its intended use over the
remaining design service life, a detailed assessment is not required.
In the case where a structure or structural members are reliable for a defined period of time, a plan for
future assessment shall be described.
When the preliminary inspection and checks are not able to give answer to the question of reliability
and serviceability of a structure or a structural member, or the information is insufficient for planning
necessary intervention, a detailed assessment shall be recommended.
4.5.3 Detailed assessment
4.5.3.1 Detailed documentary search and review
The detailed assessment shall be done based on values of basic variables corresponding to the actual
situation. For that purpose, investigation shall be intended to update the knowledge about the present
state of the structure.
This includes a more comprehensive search and review of documents than described in 4.5.2.1, and is
based on the preliminary assessment. Especially documents covering the following, if available, shall be
reviewed:
a) drawings, specifications, structural calculations, construction records, inspection and maintenance
records, details of modifications;
b) regulations, by-laws, codes and standards which were originally used for design, calculations and
execution of the structure;
c) topography, subsoil and environmental conditions, groundwater level at the site.
4.5.3.2 Detailed inspection and material testing
The aim of the detailed inspection and material testing is to determine the cause(s) for the deterioration
and the extent, as well as providing necessary information on dimensions of components and properties
of materials assumed for structural analysis and necessary for planning possible interventions. Detailed
inspection and material testing shall be carried out to collect more specific and useful data for evaluating
the detailed information. Some necessary non-destructive and/or minor-destructive test methods shall
be applied.
Detailed inspection and material testing shall result in supplementary information to the information
found in the detailed documentary search and review.
8 © ISO 2014 – All rights reserved

4.5.3.3 Determination of actions
All kind of actions, both mechanical and environmental actions on the structure or structural members,
shall be determined by analysis in accordance with ISO 2394, and evaluated on the basis of the current
design codes, and taking into account provisions laid down in the safety and utilization plan. Changes of
actions caused by the change in use or modification of the structure, shall be taken into consideration
per 6.3.2.
4.5.3.4 Determination of properties of the structures
In some situations, the response of the structure or a structural member from action(s) has to be tested
in order to predict the load-bearing capacity. This could be both static and dynamic testing. Load testing
of a structure or structural member is very costly and time-consuming. However, this type of testing
is normally not necessary, and used only when other approaches, such as detailed structural analysis
or inspection alone do not provide clear indication or have failed to demonstrate adequate structural
reliability. When this type of testing has to be performed, reference is made to ISO 13822, Annex D.
4.5.3.5 Structural analysis
Based on detailed documentary review, inspection and material testing, a structural analysis shall
be carried out to determine the effects of the actions on the structure or structural members. When
deterioration of an existing structure is observed, which is the normal situation for existing structures,
the reliability assessment of the structure becomes a time-dependent deterioration challenge and this
time-dependent development must be taken into account.
A structural analysis can be based on the principles given in ISO 2394. However, the limit state method
developed in ISO 2394, has been adopted and used for preparing and harmonizing national and regional
standards for structural design around the world, and in most situations, national codes and standards
for safety philosophy and structural calculations, have to be employed.
When time-dependent structural analysis has to be performed, some examples of appropriate analysis
methods are found in ISO 13822, Annex E. However, in most situations, national codes, standards, and
guidelines for safety philosophy and time-dependent models, can be employed.
NOTE 1 For time-dependent deterioration, it is often more practical to use limit states like time to initiation of
corrosion for reinforcement corrosion, based on data from the structure.
NOTE 2 ISO 16204 gives methods for evaluating time-dependent deterioration.
4.5.3.6 Verification
Based on the results from the evaluation and from the detailed assessment, the structural performance
shall be verified with reference to defined requirements, i.e. requirements from government (e.g.
standards, codes), owner, designer, user, etc. If necessary, structural analysis can be carried out to
investigate structural behaviours with the consideration of the investigated properties. The results
from the assessment shall be documented to clearly indicate and explain the investigated results.
Current codes and standards shall be used in the verification. Former codes and standards that were
valid at the time of construction of an existing structure shall be used as informative documents.
Alternatively, verification can be based on satisfactory past performance, taking into account time-
dependant development of deterioration processes. If this approach is to be employed, reference is made
to ISO 13822, Clause 8.
A more detailed presentation of evaluation and analysis of results of assessment for existing concrete
structures are given in Clause 7.
4.6 Reporting results of assessment
As the final step, all the investigated and assessed results shall be documented in a report as presented
in Clause 8.
4.7 Judgement and decision
Based on all information available from documentary review, inspection, and material testing, judgement
and decisions shall be made.
The condition of a structure is classified in a condition level and a consequence level (see Annex B).
The probability that a given consequence may occur for a structure, or a structural member, at the
present time or in the future, shall be evaluated. The conclusions drawn from this evaluation will provide
an estimate of the risk represented by the defect.
The risk shall be evaluated and reported and be the basis for recommending whether any immediate
action(s) are necessary or not. The consequence(s) leading to the risk shall be reported.
NOTE Annex C gives more detailed description of evaluation and verification.
If necessary, this shall end up with a project specification for maintenance and repair of a structure or
a structural member. Reference is made to 16311-3, which gives information on planning and design of
maintenance, repair, and prevention.
4.8 Intervention
When intervention of any kind is necessary, this is described in the project specification. Reference is
made to 16311-4, which gives information on the execution of maintenance, repair, and prevention.
5 Site and laboratory investigation and data collection
5.1 General
The work on site and in the laboratory is a costly part of the assessment. It shall be planned carefully to
perform the work in an effective way and on schedule.
To perform an assessment, the scope, the object to be assessed, the parties involved and their
responsibilities shall be clearly defined by a qualified person. This shall be given in a project specification
including at least
— a description of the work to be carried out, methods and the resources to be used,
— safety instructions and care to the surroundings,
— what the report shall include, and
— estimated cost and time schedule.
NOTE A project specification can, in some situations, be split into different documents. One part can be a
definition and a description of the work as a basis for tender. One part can cover the planning of the work. One part
can cover the survey and inspection itself. When a project specification is split into several parts, the subsequent
parts depend on the results of the previous parts.
5.2 Planning and execution of inspection and data collection
The procedures and items of inspection shall be properly planned to achieve the aims of the assessment.
Required detailed information for verification shall be obtained from the assessment. The engineer in
charge shall clearly understand any primary concerns on structural performance and durability, and
the importance of inspection items shall be considered before the inspection work starts.
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The planning includes all preparatory work to be done by the inspector in order to carry out the
assessment according to the purpose and scope of the assessment.
Conditions where the structure is located, that can be important for the execution of the work on site,
shall be listed. It shall be decided if a visit to the structure is necessary before finalizing the planning.
Original information of the structure like drawings, calculations, and as built information shall be
evaluated, if possible. Pre-stressed concrete structures require specialized expertise to complete their
assessment.
Information from the service life of the structure, e.g. loads, environmental exposure, earlier condition
assessments, and possible repair work, shall be evaluated, including strengthening by, e.g. composites.
A system for registration shall be worked out so that all observations and measurements are
unambiguously located on the structure.
A detailed plan for what to do where on the structure, based on the purpose and aim of the inspection,
shall be worked out.
A list of equipment shall be worked out, necessary for carrying out the planned work during the
inspection on site.
Time and cost for the planned work, both on site, in laboratory as well as evaluating the registrations
and the test results, and preparing the report, shall be a part of the planning.
The inspection and data collection shall be executed to obtain required data for verification of structural
performance, durability, and remaining service life, based on the planning of the assessment.
NOTE A.1 gives more detailed description of the planning of an assessment.
5.3 Registration of condition
5.3.1 General
Registration of condition is a systematic collection of observations and test results on site and in
laboratory. The extent of the registration shall be evaluated during the inspection to find out if the
purpose and aim of the work will be achieved.
NOTE A.2 gives more detailed description of registration of condition, including properties that can be tested
on site and in laboratory with current test methods indicated.
5.3.2 Registration and documentation of condition
The condition of a structure, or a structural member, shall be assigned by a condition level (see 4.5.2.3
and Annex B), based on one or more individual symptoms, or on a combination of more symptoms, or
on test results. The condition level shall be defined based on a reference system given in the project
specification for the assessment, condition levels may be defined in a National Annex to this part of
ISO 16311.
NOTE The reference for evaluating the condition level is normally the original state of the structure or the
structural member.
The condition shall be documented by description of visual inspection, sketches, drawings, photos, test
results, and measurements.
If a defect is registered, with or without symptoms, it shall be given together with the reference system
for evaluation of defects. Defects shall be documented by description of visual inspection, sketches,
drawings, and photos.
5.3.3 Selection of inspection items
The detailed inspection shall include tests and measurements for concrete core strength, cover thickness,
carbonation depth, chloride ion profile, and further document review and visual inspection, if necessary
(see Annex A). The details and extent of data shall meet the requirements so that the engineer can verify
structural performance, durability, and remaining service life.
5.3.3.1 Visual inspection
Visual inspection is the most important part of a preliminary assessment.
NOTE A listing of important defects/symptoms to look for in a visual inspection is given in Table A.1.
When the information from the visual inspection performed in the preliminary assessment is not enough
for fulfilling the goal of the assessment, a further visual inspection shall be done to obtain additional
data required. All possible resources related to deterioration, deformation, and any cause of problems
to the structures, shall be examined in addition to the items of visual inspection in the preliminary
assessment.
NOTE Examples of which are presented in A.3.
5.3.3.2 Tests and measurements
The basic tests and measurements during the detailed assessment may include items listed in Annex A.
Annex A has a listing of current properties and test methods to be used on site and in laboratory. The
location and number of data collecting points shall be determined in accordance with the relevant
national codes, considering types of structure and homogeneity of materials. The equipment used for the
test and measurements, shall be checked in terms of accuracy necessary for evaluation and verification.
When samples of concrete and reinforcement are required for estimation of their properties, they also
shall be taken from the locations where the removal or cutting does not diminish the structural integrity
and safety.
Actions on the structure shall be appropriately considered during the assessment. The information on
the actions can be obtained from design documents when there is no doubt in their accuracy. However,
the detailed evaluation of actions may be required when they are considered to be more severe than
those specified in design documents or national codes.
5.3.3.3 Documentation of results after inspection
The results of test and measurements, as well as document review and visual inspection in the detailed
inspection, shall be documented so that proper and efficient verification can be performed. The document
shall include at least the following information:
a) list of reviewed documents;
b) necessary part of the documents;
c) summary of document review;
d) method of visual inspection;
e) data of visual inspection including photos and figures;
f) summary of visual inspection;
g) items and methods of tests and measurements;
h) data of tests and measurements;
i) summary of tests and measurements;
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j) locations of test specimens in the structure.
NOTE Refer to Clause 8 for additional information.
6 Evaluation and verification
6.1 Evaluation of action
6.1.1 Principle
Actions used for the assessment shall be evaluated on the basis of the current design codes. Changes of
actions caused by the change in use or modification of the structure shall be taken into consideration.
6.1.2 Evaluation based on documents
If deemed appropriate, actions may be determined from construction documents and the current
design codes. For informative purposes, actions for which the structure was originally designed may
be determined from drawings and design codes valid in the period when the original structure was
designed.
6.1.3 Evaluation based on investigation
In cases when any uncertainty exists in actions, they shall be determined by investigation. Determination
of long term and extreme actions may require statistical or probabilistic analysis.
NOTE It can be advantageous to consider the specific characteristics of the structure including its surrounding
when determining actions.
6.2 Evaluation of materials and structural details
6.2.1 General
Collection of information from condition registration, including current information from construction
and operation, observation on site, results from tests on site and in laboratory is addressed in Clause 5.
This clause includes the evaluation and analysis of relevant observations and results.
6.2.2 Average value and variability
Not only the average value but also the variability of material properties and structural details, such
as strength, modulus of elasticity and cover thickness, shall be taken into account for the detailed
assessment. The variability is represented by the standard deviation (or the coefficient of variation) and
the maximum allowable acceptable probability of failure shall not be exceeded.
6.2.3 Concrete
6.2.3.1 Compressive strength
The compressive strength of concrete shall be evaluated based on the result of the detailed assessment.
6.2.3.2 Modulus of elasticity
The modulus of elasticity of concrete shall be evaluated by the test of core samples when an empirical
formula is not sufficient to derive it from the compressive strength.
6.2.3.3 Carbonation depth and rate
The vulnerability of reinforcement to carbonation-induced corrosion and future development shall be
evaluated by the principle given in ISO 16204.
6.2.3.4 Chloride concentration and diffusion coefficient
The vulnerability of reinforcement to chloride-induced corrosion and future development shall be
evaluated by the principles given in ISO 16204. The surface chloride ion concentration of concrete of the
structure and an apparent diffusion coefficient are calculated at the same time by applying regression
analysis using a solution to the diffusion equation based on Fick’s second law to the total chloride ion
concentration profile obtained from the concrete sample through chemical analysis.
6.2.3.5 Others
Frost damage, chemical deterioration, etc., shall be evaluated by acoustic, petrographic, and chemical
analyses, crack observation by microscope, and other techniques for valuable information related to the
concrete composition, present condition, and potential for future deterioration, if necessary.
6.2.4 Reinforcement
6.2.4.1 Yield strength
The yield strength of reinforcement shall be evaluated. Information on the yield strength of reinforcement
from mill test reports furnished by the manufacturer of the reinforcement or that provided by a public
institute of reinforcement for older structures can be used if the engineer and building officials are in
agreement.
6.2.4.2 Reinforcement details
Numbers, locations, and dimensions of rein
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