Assessment and retrofitting of existing structures

1.1   Scope of CEN/TS 17440
(1)This document provides additional or amended provisions to EN 1990 to cover the assessment of existing structures (see EN 1990:2002, 1.1(4)), and the retained parts of existing structures that are being modified, extended, strengthened or retrofitted.
NOTE 1   The assessment of an existing structure is, in many aspects, different from the design of a new structure, see Introduction.
NOTE 2   There can be some aspects of EN 1990 that are required for design but are not applicable for assessment. The definition of those aspects of EN 1990 that are not applicable can be included in the definition of the assessment objectives and the approach to the assessment, see 5.
NOTE 3   This document is based on the general requirements and principles of structural reliability provided in Eurocodes EN 1990 and EN 1991.
(2) This document covers general principles regarding actions for assessment complementing EN 1991.
NOTE   Supplementary provisions for seismic actions due to earthquake are provided in EN 1998.
(3) This document includes general principles for the assessment of the structural resistance of existing structures.
NOTE   The specific models used to assess resistance are not provided in this document and will depend on the materials and structure types.
(4) This document does not provide specific rules for initiation of assessment.
(5) This document does not provide specific rules on how to undertake interventions that can be carried out as a result of an assessment.
(6) This document does not cover the design of new elements that will be integrated into an existing structure.
NOTE   For the design of new elements, see EN 1990.
1.2   Assumptions
(1) The general assumptions of CEN/TS 17440 are:
-   the assessment of the structure is made by appropriately qualified and experienced personnel;
-   adequate supervision and quality control is provided during the assessment process;
-   the structure will be used in accordance with the assessment assumptions;
-   the structure will be maintained in accordance with the assessment assumptions.

Bewertung und Ertüchtigung von bestehenden Tragwerken

1.1   Anwendungsbereich von CEN/TS 17440
(1) Dieses Dokument stellt Vorgaben zur Verfügung, die zusätzlich oder in Ergänzung zu EN 1990 die Bewertung von bestehenden Tragwerken (siehe EN 1990:2002, 1.1(4)) und den noch erhaltenen Teilen von bestehenden Tragwerken, die umgebaut, erweitert, verstärkt oder ertüchtigt werden, ermöglichen.
ANMERKUNG 1   Die Bewertung eines bestehenden Tragwerks unterscheidet sich in mehrerlei Hinsicht von der Bemessung eines neuen Tragwerks, siehe Einleitung.
ANMERKUNG 2   Möglicherweise sind einige der in EN 1990 behandelten Aspekte für die Bemessung erforderlich, bei der Bewertung aber nicht anwendbar. Die Festlegung derjenigen Aspekte von EN 1990, die nicht anwendbar sind, kann in die Festlegung der Bewertungsziele und des Bewertungsansatzes einbezogen werden, siehe Abschnitt 5.
ANMERKUNG 3   Dieses Dokument basiert auf den in den Eurocodes EN 1990 und EN 1991 festgelegten allgemeinen Anforderungen und Grundsätzen der Zuverlässigkeit des Tragwerks.
(2) Dieses Dokument deckt allgemeine Grundsätze bezüglich der Wirkungen für die Bewertung in Ergänzung von EN 1991 ab.
ANMERKUNG   EN 1998 enthält ergänzende Vorgaben für seismische Wirkungen aufgrund von Erdbeben.
(3) Dieses Dokument enthält allgemeine Grundsätze für die Bewertung der Beanspruchbarkeit von bestehenden Tragwerken.
ANMERKUNG   Das vorliegende Dokument enthält nicht die spezifischen zur Bewertung der Beanspruchbarkeit herangezogenen Modelle; diese sind von den Werkstoffen und den Tragwerkstypen abhängig.
(4) Dieses Dokument enthält keine spezifischen Regeln für die Inangriffnahme einer Bewertung.
(5) Dieses Dokument enthält keine spezifischen Regeln dazu, wie Eingriffe vorzunehmen sind, die aufgrund einer Bewertung durchgeführt werden können.
(6) Dieses Dokument deckt nicht die Bemessung von neuen Bauelementen ab, die in ein bestehendes Tragwerk eingebaut werden.
ANMERKUNG   Zur Bemessung von neuen Bauelementen siehe EN 1990.
1.2   Annahmen
(1) CEN/TS 17440 geht von den folgenden allgemeinen Annahmen aus:
-   Die Bewertung des Tragwerks wird von dafür entsprechend qualifizierten und erfahrenen Personen durchgeführt;
-   sachgerechte Aufsicht und Güteüberwachung sind während des Bewertungsprozesses sichergestellt;
-   das Tragwerk wird den Bewertungsannahmen entsprechend genutzt;
-   das Tragwerk wird den Bewertungsannahmen entsprechend instandgehalten.

Evaluation et rénovation des structures existantes

1.1   Domaine d’application de la CEN/TS 17440
(1) Le présent document fournit des dispositions additionnelles ou modifiées par rapport à l’EN 1990 pour couvrir l’évaluation des structures existantes (voir l’EN 1990:2002, 1.1(4)), et des parties conservées des structures existantes qui sont modifiées, agrandies, renforcées ou rénovées.
NOTE 1   L’évaluation d’une structure existante diffère, à bien des égards, du calcul d’une nouvelle structure (voir l’Introduction).
NOTE 2   Il est possible que certains aspects de l’EN 1990 soient requis pour le calcul d’un ouvrage neuf mais ne soient pas applicables pour l’évaluation d’un ouvrage existant. La définition des aspects de l’EN 1990 qui ne sont pas applicables peut être incluse dans la définition des objectifs et de l’approche de l’évaluation (voir l’Article 5).
NOTE 3   Le présent document est basé sur les exigences générales et les principes de fiabilité structurale fournis dans les Eurocodes EN 1990 et EN 1991.
(2) Le présent document couvre pour une évaluation les principes généraux concernant les actions en complément de l’EN 1991.
NOTE   Des dispositions complémentaires pour les actions sismiques dues aux séismes sont fournies dans l’EN 1998.
(3) Le présent document énonce les principes généraux pour l’évaluation de la résistance structurale des structures existantes.
NOTE   Les modèles spécifiques utilisés pour évaluer la résistance ne sont pas fournis dans le présent document et dépendent des matériaux et des types de structure.
(4) Le présent document ne fournit pas de règles spécifiques pour le lancement d’une évaluation.
(5) Le présent document ne fournit pas de règles spécifiques sur la manière de réaliser les interventions pouvant être effectuées à la suite d’une évaluation.
(6) Le présent document ne couvre pas le calcul des nouveaux éléments qui seront intégrés dans une structure existante.
NOTE   Pour le calcul des nouveaux éléments, voir l’EN 1990.
1.2   Hypothèses
(1) Les hypothèses générales de la CEN/TS 17440 sont les suivantes :
-   l’évaluation de la structure est effectuée par un personnel suffisamment qualifié et expérimenté ;
-   une surveillance et une maîtrise de la qualité adéquates sont assurées au cours du processus d’évaluation ;
-   l’utilisation de la structure sera conforme aux hypothèses admises dans l’évaluation ;
-   la maintenance de la structure sera conforme aux hypothèses admises dans l’évaluation.

Ocenjevanje in obnova obstoječih stavb

General Information

Status
Published
Public Enquiry End Date
19-Mar-2020
Publication Date
13-Sep-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
28-Jul-2020
Due Date
02-Oct-2020
Completion Date
14-Sep-2020

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Standards Content (Sample)

SLOVENSKI STANDARD
SIST-TS CEN/TS 17440:2020
01-oktober-2020
Ocenjevanje in obnova obstoječih stavb
Assessment and retrofitting of existing structures
Bewertung und Ertüchtigung von bestehenden Tragwerken
Evaluation et rénovation des structures existantes
Ta slovenski standard je istoveten z: CEN/TS 17440:2020
ICS:
91.010.30 Tehnični vidiki Technical aspects
91.040.01 Stavbe na splošno Buildings in general
SIST-TS CEN/TS 17440:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TS CEN/TS 17440:2020
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SIST-TS CEN/TS 17440:2020
CEN/TS 17440
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
July 2020
TECHNISCHE SPEZIFIKATION
ICS 91.010.30
English Version
Assessment and retrofitting of existing structures

Évaluation et rénovation des structures existantes Bewertung und Ertüchtigung von bestehenden

Tragwerken

This Technical Specification (CEN/TS) was approved by CEN on 3 May 2020 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to

submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS

available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in

parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 17440:2020 E

worldwide for CEN national Members.
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Contents Page

European foreword ............................................................................................................................................ 4

Introduction .......................................................................................................................................................... 5

1 Scope .......................................................................................................................................................... 7

1.1 Scope of CEN/TS 17440 ....................................................................................................................... 7

1.2 Assumptions ........................................................................................................................................... 7

2 Normative references .......................................................................................................................... 7

3 Terms, definitions and symbols ...................................................................................................... 8

3.1 Terms and definitions ......................................................................................................................... 8

3.2 Symbols .................................................................................................................................................. 11

4 Principles of assessment .................................................................................................................. 13

4.1 Reliability management ................................................................................................................... 13

4.2 Methods of assessment ..................................................................................................................... 13

4.3 Assessment situations ....................................................................................................................... 13

4.4 Using available information ............................................................................................................ 14

4.5 Updating available information..................................................................................................... 14

4.6 Structures with new elements and retained elements ......................................................... 14

4.7 Assessment of heritage structures ............................................................................................... 14

5 Assessment process ........................................................................................................................... 15

5.1 General.................................................................................................................................................... 15

5.2 Initiating the assessment ................................................................................................................. 15

5.3 Agreeing the assessment scope and objectives ....................................................................... 15

5.4 Developing the assessment approach ......................................................................................... 17

5.5 Establishing the structural condition .......................................................................................... 17

5.6 Undertaking the assessment .......................................................................................................... 19

5.7 Reporting the assessment findings .............................................................................................. 20

6 Assessment by calculation ............................................................................................................... 20

6.1 General.................................................................................................................................................... 20

6.2 Assessment of action effects ........................................................................................................... 20

6.3 Assessment of resistances ............................................................................................................... 21

6.4 Verifications .......................................................................................................................................... 21

7 Basic variables and updating .......................................................................................................... 22

7.1 General.................................................................................................................................................... 22

7.2 Geometrical data ................................................................................................................................. 23

7.3 Actions and environmental influences ....................................................................................... 23

7.4 Material and product properties ................................................................................................... 26

8 Structural modelling, updating and analysis ............................................................................ 28

8.1 Structural layout and boundary conditions .............................................................................. 28

8.2 Structural analysis principles ........................................................................................................ 28

8.3 Selection of structural analysis methodology .......................................................................... 28

8.4 Testing and monitoring .................................................................................................................... 29

9 Verifications .......................................................................................................................................... 30

9.1 General.................................................................................................................................................... 30

9.2 Verification methods ......................................................................................................................... 30

9.3 Partial factor method ........................................................................................................................ 30

9.4 Assessment value method ............................................................................................................... 32

9.5 Probabilistic method ......................................................................................................................... 33

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9.6 Risk assessment method .................................................................................................................. 33

10 Assessment based on past performance .................................................................................... 34

11 Interventions ........................................................................................................................................ 35

11.1 Developing proposals for interventions based on the assessment results ................... 35

11.2 Immediate interventions ................................................................................................................. 36

Annex A (informative) Flowchart of assessment processes and interventions ........................ 37

A.1 Use of this informative Annex ........................................................................................................ 37

A.2 Scope and field of application ........................................................................................................ 37

Annex B (informative) Updating procedures ........................................................................................ 39

B.1 Use of this informative annex......................................................................................................... 39

B.2 Scope and field of application ........................................................................................................ 39

B.3 Updating the basic variables .......................................................................................................... 39

B.4 Updating the failure probabilities ................................................................................................ 42

Annex C (informative) Target reliability and partial factors ........................................................... 43

C.1 Use of this Informative Annex ........................................................................................................ 43

C.2 Scope and field of application ........................................................................................................ 43

C.3 Target reliability ................................................................................................................................. 43

C.4 Partial factors ....................................................................................................................................... 44

Annex D (informative) Assessment of heritage structures .............................................................. 47

D.1 Use of this Informative Annex ........................................................................................................ 47

D.2 Scope and field of application ........................................................................................................ 47

D.3 Principles of assessment .................................................................................................................. 47

D.4 Assessment process ........................................................................................................................... 47

D.5 Assessment based on past performance .................................................................................... 48

D.6 Structural modelling and analysis ................................................................................................ 48

D.7 Verification ........................................................................................................................................... 49

D.8 Interventions ........................................................................................................................................ 49

Bibliography ....................................................................................................................................................... 50

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European foreword

This document (CEN/TS 17440:2020) has been prepared by Technical Committee CEN/TC 250

“Structural Eurocodes”, the secretariat of which is held by BSI. CEN/TC 250 is responsible for all

Structural Eurocodes and has been assigned responsibility for structural and geotechnical design matters

by CEN.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document has been prepared under Mandate M/515 issued to CEN by the European Commission

and the European Free Trade Association.

This document has been drafted to be used in conjunction with relevant execution, material, product and

test standards, and to identify requirements for execution, materials, products and testing that are relied

upon by this document.

This document recognizes the responsibility of each Member State and has safeguarded their right to

determine values related to regulatory safety matters at national level through the use of National

Annexes.

The presentation, in Notes to clauses, of national choice in this Technical Specification, does not

everywhere accord with the guidance established by CEN/TC 250 for use in the Eurocode ENs. The

presentation of National choice will be in accordance with the TC’s guidance in formal ENs.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the

following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,

Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of

North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United

Kingdom.
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Introduction
General

The Eurocodes comprise rules that are primarily intended for the design of new structures, although the

principles of EN 1990 can also be applied for existing structures, with additional or amended provisions.

CEN/TS 17440 is intended to supply those additional or amended provisions that can enable EN 1990 to

be applied to the structural assessment of existing structures.

Extending the life of existing structural assets is a key challenge for structure owners worldwide.

Investment in accurately assessing the resistance of structures can deliver substantial environmental,

economic and socio-political benefits. In order to fully realize these benefits, it is often necessary in

assessment to go beyond the simple, conservative methods typically used for design, so that reliability of

structures can be more accurately assessed.

In the design of new structures, it is generally necessary to use conservative values for basic variables,

and it is typical to use conservative models for structural analysis. However, when assessing an existing

structure, there is an opportunity to obtain updated data regarding the structure, including its geometry,

its material properties, the actions and environmental influences, and measures relating to its structural

behaviour. There can be significant benefits to be gained from using updated data in the assessment, and

by considering alternative structural analysis models that represent more accurately the limit states

being assessed. CEN/TS 17440 includes provisions related to using updated data and updated structural

models in assessment.

Older structures were often designed and constructed in a way that would not conform with modern

standards for structural design, material products or execution. They can often exhibit deterioration or

damage. A particular challenge in assessment is therefore how to accurately assess structures taking

account of the actual detailing arrangements, material properties, execution tolerances, and the

structural condition. CEN/TS 17440 includes principles for the assessment of structural resistance.

Often, an older structure could need to be modified, extended, repurposed, strengthened or retrofitted in

a way that reuses retained structural elements in combination with new structural elements. In such

schemes, there will be a need to assess the retained elements of the structure, which might not conform

to all the requirements for new design. CEN/TS 17440 includes provisions for the assessment of retained

elements, as well as for the assessment of complete structures.

This document is based on the recommendation of JRC Science and Policy Report on assessment and

retrofitting of existing structures. Upon the agreement of CEN/TC 250, this document can be converted

into a new Eurocode Part.
Verbal forms used in this Technical Specification

The verb “shall” expresses a requirement strictly to be followed and from which no deviation is permitted

in order to comply with the Eurocodes.

The verb “should” expresses a highly recommended choice or course of action. Subject to national

regulation and/or any relevant contractual provisions, alternative approaches could be used/adopted

where technically justified.

The verb “may” expresses a course of action permissible within the limits of the Eurocodes.

The verb “can” expresses possibility and capability; it is used for statements of fact and clarification of

concepts.
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National annex for CEN/TS 17440

This document gives values within notes indicating where national choices can be made. Therefore, a

national document implementing CEN/TS 17440 can have a National Annex containing all Nationally

Determined Parameters to be used for the assessment of buildings and civil engineering works in the

relevant country.
National choice is possible in CEN/TS 17440 through the following clauses:

4.1(1), 4.1(3), 4.4(2), 4.6(3), 5.3(1), 5.3(2), 5.3.(3), 6.1(2), 6.3(2), 7.1(5), 7.3.1(4), 7.3.8(1), 7.3.9(1),

7.3.9(2), 7.4.1.4(1), 9.2(1), 9.3(2), 9.3(3), 9.4(4), 9.4(5), 9.5(2), 10(1), D.3.1(1).

National choice is possible in CEN/TS 17440 on the application of the following informative annexes:

• Annex A,
• Annex B,
• Annex C,
• Annex D.
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1 Scope
1.1 Scope of CEN/TS 17440

(1)This document provides additional or amended provisions to EN 1990 to cover the assessment of

existing structures (see EN 1990:2002, 1.1(4)), and the retained parts of existing structures that are being

modified, extended, strengthened or retrofitted.

NOTE 1 The assessment of an existing structure is, in many aspects, different from the design of a new structure,

see Introduction.

NOTE 2 There can be some aspects of EN 1990 that are required for design but are not applicable for assessment.

The definition of those aspects of EN 1990 that are not applicable can be included in the definition of the assessment

objectives and the approach to the assessment, see Clause 5.

NOTE 3 This document is based on the general requirements and principles of structural reliability provided in

Eurocodes EN 1990 and EN 1991.

(2) This document covers general principles regarding actions for assessment complementing EN 1991.

NOTE Supplementary provisions for seismic actions due to earthquake are provided in EN 1998.

(3) This document includes general principles for the assessment of the structural resistance of existing

structures.

NOTE The specific models used to assess resistance are not provided in this document and will depend on the

materials and structure types.
(4) This document does not provide specific rules for initiation of assessment.

(5) This document does not provide specific rules on how to undertake interventions that can be carried

out as a result of an assessment.

(6) This document does not cover the design of new elements that will be integrated into an existing

structure.
NOTE For the design of new elements, see EN 1990.
1.2 Assumptions
(1) The general assumptions of CEN/TS 17440 are:

• the assessment of the structure is made by appropriately qualified and experienced personnel;

• adequate supervision and quality control is provided during the assessment process;

• the structure will be used in accordance with the assessment assumptions;

• the structure will be maintained in accordance with the assessment assumptions.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1990:2002, Eurocode —Basis of structural design
EN 1991, Eurocode 1: Actions on structures
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3 Terms, definitions and symbols
3.1 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 1990 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1.1
assessment

set of activities performed in order to verify the reliability of an existing structure

[SOURCE: ISO 13822:2010, 3.1 — modified]
3.1.2
assessment situation

physical conditions that could occur during a certain time period for which the assessment is intended to

demonstrate, with sufficient reliability, that relevant limit states are not exceeded

3.1.3
assessment value

value of a variable applied in the analysis and verification of the structural performance of an existing

structure determined from a characteristic or another representative value combined with partial and/or

conversion factors, or also directly defined values
3.1.4
damage

unfavourable change in the condition of a structure that can adversely affect structural performance

[SOURCE: ISO 13822:2010, 3.2 — modified]
3.1.5
defect

deficiency of a structure resulting from errors during design, construction, prior intervention or lack of

maintenance
3.1.6
deterioration

process that adversely affects the structural performance, including reliability, over time, for example

due to:
• naturally occurring chemical, physical or biological actions;
• repeated actions such as those causing fatigue;
• wear due to use
[SOURCE: ISO 13822:2010, 3.3 — modified]
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3.1.7
deterioration model

mathematical model that describes structural performance as a function of time, taking deterioration into

account
3.1.8
existing structure
structure that physically (materially) exists, including its foundation and soil
3.1.9
heritage structure

existing structure or structural component that has been recognized by the relevant authorities for its

architectural or historical value

Note 1 to entry: Heritage structures can include all kinds of buildings, bridges and civil engineering works,

including their foundations.
3.1.10
inspection

on-site non-destructive examination of a structure and/or its components with the objective of

establishing the present condition of the structure and updating information as relevant

[SOURCE: ISO 13822:2010, 3.5 — modified]
3.1.11
investigation

collection and evaluation of information through inspection, document search, measurements, material

testing, load testing and other testing
[SOURCE: ISO 13822:2010, 3.6 — modified]
3.1.12
load testing

test of a structure or part thereof by loading to evaluate its behaviour or properties, to predict or

determine its load-bearing capacity
[SOURCE: ISO 13822:2010, 3.7 — modified]
3.1.13
material properties
mechanical, physical or chemical attributes of construction materials
[SOURCE: ISO 13822:2010, 3.9 — modified]
3.1.14
material testing

test of construction material to evaluate, or to predict its mechanical, physical or chemical properties

3.1.15
monitoring

frequent or continuous observation or measurement of structural conditions or actions

[SOURCE: ISO 13822:2010, 3.10 — modified]
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3.1.16
reference period

chosen period of time which is used as a basis for determining values of variable actions, time-dependent

material properties and relevant reliability
[SOURCE: ISO 13822:2010, 3.11 — modified]
3.1.17
rehabilitation

structural intervention (repair, upgrade) to reach compliance with required structural performance

3.1.18
reliability

the ability of a structure or a structural member to fulfil the specified requirements during its remaining

working life
[SOURCE: EN 1990:2002 — modified]
3.1.19
remaining working life

period for which an existing structure is intended/expected to operate with planned maintenance

[SOURCE: ISO 13822:2010, 3.13 — modified]
3.1.20
structural performance

qualitative or quantitative measure of structural behaviour under expected circumstances in terms of its

safety, serviceability, durability or robustness
3.1.21
target reliability level

the value of reliability that is specified to be achieved in the assessment, indicating that a structure is able

to fulfil its specified requirements over the remaining working life
3.1.22
updating
process of supplementing existing knowledge with new information for assessment
3.1.23
upgrading
modifications to an existing structure to improve its structural performance
[SOURCE: ISO 13822:2010, 3.18]
3.1.24
utilization plan

plan containing the intended use (or uses) during the remaining working life of an existing structure, and

listing the operational conditions of the structure including maintenance requirements, and the

corresponding performance requirements
[SOURCE: ISO 13822:2010, 3.19 — modified]
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3.2 Symbols
For the purposes of this document, the following symbols apply.
3.2.1 Latin upper-case letters
is the assessment value of the effect of actions
characteristic value of permanent action
kj,
target probability of failure for a given reference period
characteristic value of prestress action
characteristic value of the leading variable action
k,1
characteristic value of accompanying variable actions
ki,
is the assessment value of the resistance
V coefficient of variation
characteristic values of the material or product properties
ki,
3.2.2 Latin lower-case letters
assessment values of the geometrical data
k independence period
n reference period
basic variable i
characteristic value of the basic variable x
assessment value of the basic variable x
3.2.3 Greek upper-case letters
cumulative distribution function of the normal distribution
−1 inverse cumulative distribution function of the normal distribution
3.2.4 Greek lower-case letters
sensitivity factor for load effect
sensitivity factor for resistance
target reliability index
partial factor of the variable x
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partial factor for permanent actions, taking account of unfavourable deviations of the

gj,
action values from the representative values
partial factor for permanent actions, equal to γγ
Gj,
Sa g, j

partial factors to take account of the possibility of an unfavourable deviation of a

mi,

material or product property from its characteristic value and the random part of the

conversion factor
partial factors for the material or product properties, equal to γγ
Mi,
Ra m,i

partial factor for prestress actions, taking account of unfavourable deviations of the

action values from the representative values
γ partial
...

SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 17440:2020
01-marec-2020
Ocenjevanje in obnova obstoječih stavb
Assessment and retrofitting of existing structures
Bewertung und Ertüchtigung von bestehenden Tragwerken
Evaluation et rénovation des structures existantes
Ta slovenski standard je istoveten z: FprCEN/TS 17440
ICS:
91.010.30 Tehnični vidiki Technical aspects
kSIST-TS FprCEN/TS 17440:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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kSIST-TS FprCEN/TS 17440:2020
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kSIST-TS FprCEN/TS 17440:2020
FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 17440
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
January 2020
ICS 91.010.30
English Version
Assessment and retrofitting of existing structures

Evaluation et rénovation des structures existantes Bewertung und Ertüchtigung von bestehenden

Tragwerken

This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee

CEN/TC 250.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

Warning : This document is not a Technical Specification. It is distributed for review and comments. It is subject to change

without notice and shall not be referred to as a Technical Specification.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 17440:2020 E

worldwide for CEN national Members.
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kSIST-TS FprCEN/TS 17440:2020
FprCEN/TS 17440:2020 (E)
Contents Page

European foreword ............................................................................................................................................ 5

Introduction .......................................................................................................................................................... 6

1 Scope .......................................................................................................................................................... 8

1.1 Scope of CEN/TS 17440 ....................................................................................................................... 8

1.2 Assumptions ........................................................................................................................................... 8

2 Normative references .......................................................................................................................... 8

3 Terms and definitions ......................................................................................................................... 9

3.1 Terms ........................................................................................................................................................ 9

3.2 Symbols .................................................................................................................................................. 12

3.2.1 Latin upper-case letters .................................................................................................................... 12

3.2.2 Latin lower-case letters .................................................................................................................... 12

3.2.3 Greek upper-case letters .................................................................................................................. 12

3.2.4 Greek lower-case letters .................................................................................................................. 12

4 Principles of assessment .................................................................................................................. 13

4.1 Reliability management ................................................................................................................... 13

4.2 Methods of assessment ..................................................................................................................... 14

4.3 Assessment situations ....................................................................................................................... 14

4.4 Using available information ............................................................................................................ 14

4.5 Updating available information..................................................................................................... 15

4.6 Structures with new elements and retained elements ......................................................... 15

4.7 Assessment of heritage structures ............................................................................................... 15

5 Assessment process ........................................................................................................................... 15

5.1 General.................................................................................................................................................... 15

5.2 Initiating the assessment ................................................................................................................. 16

5.3 Agreeing the assessment scope and objectives ....................................................................... 16

5.4 Developing the assessment approach ......................................................................................... 17

5.5 Establishing the structural condition .......................................................................................... 18

5.5.1 General.................................................................................................................................................... 18

5.5.2 Condition survey ................................................................................................................................. 18

5.5.3 Further structural investigations ................................................................................................. 18

5.5.4 Planning ................................................................................................................................................. 18

5.5.5 Implementation ................................................................................................................................... 19

5.5.6 Evaluation .............................................................................................................................................. 19

5.6 Undertaking the assessment .......................................................................................................... 19

5.6.1 Preliminary assessment ................................................................................................................... 19

5.6.2 Detailed assessment .......................................................................................................................... 20

5.6.3 Plausibility check ................................................................................................................................ 20

5.7 Reporting the assessment findings .............................................................................................. 20

6 Assessment by calculation ............................................................................................................... 21

6.1 General.................................................................................................................................................... 21

6.2 Assessment of action effects ........................................................................................................... 21

6.3 Assessment of resistances ............................................................................................................... 21

6.4 Verifications .......................................................................................................................................... 22

7 Basic variables and updating .......................................................................................................... 22

7.1 General.................................................................................................................................................... 22

7.2 Geometrical data ................................................................................................................................. 23

7.3 Actions and environmental influences ....................................................................................... 23

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FprCEN/TS 17440:2020 (E)

7.3.1 Self-weight of structures and permanent actions due to the weight of non-structural

materials ................................................................................................................................................ 23

7.3.2 Imposed deformations...................................................................................................................... 24

7.3.3 Prestressing .......................................................................................................................................... 24

7.3.4 Imposed loads on buildings ............................................................................................................ 24

7.3.5 Snow loads............................................................................................................................................. 24

7.3.6 Wind actions ......................................................................................................................................... 25

7.3.7 Thermal actions .................................................................................................................................. 25

7.3.8 Accidental actions............................................................................................................................... 25

7.3.9 Traffic loads on bridges .................................................................................................................... 26

7.3.10 Geotechnical actions .......................................................................................................................... 26

7.3.11 Environmental influences ............................................................................................................... 26

7.4 Material and product properties .................................................................................................. 27

7.4.1 Construction materials ..................................................................................................................... 27

7.4.2 Geotechnical properties ................................................................................................................... 28

8 Structural modelling, updating and analysis ............................................................................ 29

8.1 Structural layout and boundary conditions .............................................................................. 29

8.2 Structural analysis principles ........................................................................................................ 29

8.3 Selection of structural analysis methodology .......................................................................... 29

8.4 Testing and monitoring .................................................................................................................... 29

8.4.1 Combination of testing and/or monitoring with structural analysis .............................. 29

8.4.2 Objectives of testing ........................................................................................................................... 30

9 Verifications ......................................................................................................................................... 30

9.1 General ................................................................................................................................................... 30

9.2 Verification methods ......................................................................................................................... 31

9.3 Partial factor method ........................................................................................................................ 31

9.4 Assessment value method ............................................................................................................... 33

9.5 Probabilistic method ......................................................................................................................... 34

9.6 Risk assessment method .................................................................................................................. 34

10 Assessment based on past performance .................................................................................... 34

11 Interventions ........................................................................................................................................ 35

11.1 Developing proposals for interventions based on the assessment results ................... 35

11.2 Immediate interventions ................................................................................................................. 36

Annex A (informative) Flowchart of assessment processes and interventions ........................ 37

A.1 Use of this informative Annex ........................................................................................................ 37

A.2 Scope and field of application ........................................................................................................ 37

Annex B (informative) Updating procedures ........................................................................................ 39

B.1 Use of this informative annex......................................................................................................... 39

B.2 Scope and field of application ........................................................................................................ 39

B.3 Updating the basic variables .......................................................................................................... 39

B.3.1 Prior information ............................................................................................................................... 39

B.3.2 Posterior normal distribution ....................................................................................................... 40

B.3.3 Assessment values .............................................................................................................................. 41

B.3.4 Characteristic values ......................................................................................................................... 41

B.4 Updating the failure probabilities ................................................................................................ 41

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B.4.1 Direct updating .................................................................................................................................... 41

B.4.2 Load testing ........................................................................................................................................... 42

B.4.3 Satisfactory past performance ....................................................................................................... 42

Annex C (informative) Target reliability and partial factors ........................................................... 43

C.1 Use of this Informative Annex ........................................................................................................ 43

C.2 Scope and field of application ........................................................................................................ 43

C.3 Target reliability ................................................................................................................................. 43

C.3.1 General.................................................................................................................................................... 43

C.3.2 Reliability index .................................................................................................................................. 43

C.4 Partial factors ....................................................................................................................................... 44

C.4.1 General.................................................................................................................................................... 44

C.4.2 Basic procedure ................................................................................................................................... 44

Annex D (informative) Assessment of heritage structures ............................................................... 47

D.1 Use of this Informative Annex ........................................................................................................ 47

D.2 Scope and field of application ........................................................................................................ 47

D.3 Principles of assessment .................................................................................................................. 47

D.3.1 Reliability management ................................................................................................................... 47

D.3.2 Preservation of original materials and structural concept ................................................. 47

D.4 Assessment process ........................................................................................................................... 47

D.4.1 General.................................................................................................................................................... 47

D.4.2 Establishing the structural conditions ........................................................................................ 48

D.4.3 Undertaking the assessment .......................................................................................................... 48

D.4.3.1 Preliminary assessment ................................................................................................................... 48

D.4.3.2 Detailed assessment .......................................................................................................................... 48

D.5 Assessment based on past performance .................................................................................... 48

D.6 Structural modelling and analysis ................................................................................................ 48

D.6.1 Models of heritage structures ........................................................................................................ 48

D.6.2 Structural analysis for assessment ............................................................................................... 49

D.7 Verification ............................................................................................................................................ 49

D.8 Interventions ........................................................................................................................................ 49

Bibliography ....................................................................................................................................................... 50

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FprCEN/TS 17440:2020 (E)
European foreword

This document (FprCEN/TS 17440:2020) has been prepared by Technical Committee CEN/TC 250

“Structural Eurocodes”, the secretariat of which is held by BSI. CEN/TC 250 is responsible for all

Structural Eurocodes and has been assigned responsibility for structural and geotechnical design matters

by CEN.
This document is currently submitted to the Vote on TS.

This document has been prepared under Mandate M/515 issued to CEN by the European Commission

and the European Free Trade Association.

This document has been drafted to be used in conjunction with relevant execution, material, product and

test standards, and to identify requirements for execution, materials, products and testing that are relied

upon by this document.

This document recognizes the responsibility of each Member State and has safeguarded their right to

determine values related to regulatory safety matters at national level through the use of National

Annexes.

The presentation, in Notes to clauses, of national choice in this Technical Specification, does not

everywhere accord with the guidance established by CEN/TC 250 for use in the Eurocode ENs. The

presentation of National choice will be in accordance with the TC’s guidance in formal ENs.

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FprCEN/TS 17440:2020 (E)
Introduction
General

The Eurocodes comprise rules that are primarily intended for the design of new structures, although the

principles of EN 1990 can also be applied for existing structures, with additional or amended provisions.

CEN/TS 17440 is intended to supply those additional or amended provisions that can enable EN 1990 to

be applied to the structural assessment of existing structures.

Extending the life of existing structural assets is a key challenge for structure owners worldwide.

Investment in accurately assessing the resistance of structures can deliver substantial environmental,

economic and socio-political benefits. In order to fully realize these benefits, it is often necessary in

assessment to go beyond the simple, conservative methods typically used for design, so that reliability of

structures can be more accurately assessed.

In the design of new structures, it is generally necessary to use conservative values for basic variables,

and it is typical to use conservative models for structural analysis. However, when assessing an existing

structure, there is an opportunity to obtain updated data regarding the structure, including its geometry,

its material properties, the actions and environmental influences, and measures relating to its structural

behaviour. There can be significant benefits to be gained from using updated data in the assessment, and

by considering alternative structural analysis models that represent more accurately the limit states

being assessed. CEN/TS 17440 includes provisions related to using updated data and updated structural

models in assessment.

Older structures were often designed and constructed in a way that would not conform with modern

standards for structural design, material products or execution. They can often exhibit deterioration or

damage. A particular challenge in assessment is therefore how to accurately assess structures taking

account of the actual detailing arrangements, material properties, execution tolerances, and the

structural condition. CEN/TS 17440 includes principles for the assessment of structural resistance.

Often, an older structure could need to be modified, extended, repurposed, strengthened or retrofitted in

a way that reuses retained structural elements in combination with new structural elements. In such

schemes, there will be a need to assess the retained elements of the structure, which might not conform

to all the requirements for new design. CEN/TS 17440 includes provisions for the assessment of retained

elements, as well as for the assessment of complete structures.

This document is based on the recommendation of JRC Science and Policy Report on assessment and

retrofitting of existing structures. Upon the agreement of CEN/TC 250, this document can be converted

into a new Eurocode Part.
Verbal forms used in this Technical Specification

The verb “shall” expresses a requirement strictly to be followed and from which no deviation is permitted

in order to comply with the Eurocodes.

The verb “should” expresses a highly recommended choice or course of action. Subject to national

regulation and/or any relevant contractual provisions, alternative approaches could be used/adopted

where technically justified.

The verb “may” expresses a course of action permissible within the limits of the Eurocodes.

The verb “can” expresses possibility and capability; it is used for statements of fact and clarification of

concepts.
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kSIST-TS FprCEN/TS 17440:2020
FprCEN/TS 17440:2020 (E)
National annex for CEN/TS 17440

This document gives values within notes indicating where national choices can be made. Therefore, a

national document implementing CEN/TS 17440 can have a National Annex containing all Nationally

Determined Parameters to be used for the assessment of buildings and civil engineering works in the

relevant country.
National choice is possible in CEN/TS 17440 through the following clauses:

4.1(1), 4.1(3), 4.4(2), 4.6(3), 5.3(1), 5.3(2), 5.3.(3), 6.1(2), 6.3(2), 7.1(5), 7.3.1(4), 7.3.8(1), 7.3.9(1),

7.3.9(2), 7.4.1.4(1), 9.2(1), 9.3(2), 9.3(3), 9.4(4), 9.4(5), 9.5(2), 10(1), D.3.1(1).

National choice is possible in CEN/TS 17440 on the application of the following informative annexes:

• Annex A,
• Annex B,
• Annex C,
• Annex D.
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kSIST-TS FprCEN/TS 17440:2020
FprCEN/TS 17440:2020 (E)
1 Scope
1.1 Scope of CEN/TS 17440

(1)This document provides additional or amended provisions to EN 1990 to cover the assessment of

existing structures (see EN 1990:2002, 1.1(4)), and the retained parts of existing structures that are being

modified, extended, strengthened or retrofitted.

NOTE 1 The assessment of an existing structure is, in many aspects, different from the design of a new structure,

see Introduction.

NOTE 2 There can be some aspects of EN 1990 that are required for design but are not applicable for assessment.

The definition of those aspects of EN 1990 that are not applicable can be included in the definition of the assessment

objectives and the approach to the assessment, see 5.

NOTE 3 This document is based on the general requirements and principles of structural reliability provided in

Eurocodes EN 1990 and EN 1991.

(2) This document covers general principles regarding actions for assessment complementing EN 1991.

NOTE Supplementary provisions for seismic actions due to earthquake are provided in EN 1998.

(3) This document includes general principles for the assessment of the structural resistance of existing

structures.

NOTE The specific models used to assess resistance are not provided in this document and will depend on the

materials and structure types.
(4) This document does not provide specific rules for initiation of assessment.

(5) This document does not provide specific rules on how to undertake interventions that can be carried

out as a result of an assessment.

(6) This document does not cover the design of new elements that will be integrated into an existing

structure.
NOTE For the design of new elements, see EN 1990.
1.2 Assumptions
(1) The general assumptions of CEN/TS 17440 are:

• the assessment of the structure is made by appropriately qualified and experienced personnel;

• adequate supervision and quality control is provided during the assessment process;

• the structure will be used in accordance with the assessment assumptions;

• the structure will be maintained in accordance with the assessment assumptions.

2 Normative references

(1) The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

EN 1990:2002, Eurocode —Basis of structural design
EN 1991, Eurocode 1: Actions on structures
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kSIST-TS FprCEN/TS 17440:2020
FprCEN/TS 17440:2020 (E)
3 Terms and definitions

(1) For the purposes of this document, the terms and definitions given in EN 1990 and the following

apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Terms
3.1.1
assessment

set of activities performed in order to verify the reliability of an existing structure

[SOURCE: ISO 13822:2010, 3.1 — modified]
3.1.2
assessment s
...

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