SIST EN 13230-6:2020

Railway applications - Track - Concrete sleepers and bearers - Part 6: Design

This document provides particular design guidance in the following areas:
-   derivation of characteristic loads and test loads;
-   calculation of characteristic and test bending moments.
The aim of this document is to give guidance for the preparation of all data to be given by the purchaser to the supplier in accordance with Parts 1 to 5 of EN 13230. It applies to gauges 1 000 mm, 1 435 mm, 1 668 mm as well as to all lengths of sleepers and bearers.
This standard gives special criteria for the design of concrete sleepers and bearers as track components. The design methods in the Eurocode do not apply to these concrete elements.
All track parameters to be taken into account for the design of sleepers and bearers are detailed in this standard. Information is given on these parameters so that they can be used as inputs for the design calculation process. It is the responsibility of the purchaser to calculate or determine all track parameters used in this standard.
This standard gives guidance for the design calculation process. It explains how experience and calculation can be combined to use design parameters.
This standard gives examples of numerical data that can be used when applying Clauses 4 to 6 according to the state of the art.

Bahnanwendungen - Oberbau - Gleis- und Weichenschwellen aus Beton - Teil 6: Entwurf

Dieses Dokument enthält einschlägige Entwurfsrichtlinien für die folgenden Bereiche:
- die Herleitung von charakteristischen Lasten und Prüflasten;
- die Berechnung von charakteristischen Biegemomenten und Prüfbiegemomenten.
Ziel dieses Dokuments ist die Bereitstellung einer Anleitung zur Vorbereitung aller Daten, die der Kunde dem Lieferanten in Übereinstimmung mit EN 13230, Teil 1 bis Teil 5, zur Verfügung stellen muss. Sie gilt sowohl für die Spurweiten 1 000 mm, 1 435 mm und 1 668 mm als auch für alle Längen von Gleis  und Weichenschwellen.
Dieses Dokument enthält besondere Kriterien für die Bemessung von Gleis  und Weichenschwellen aus Beton als Gleiskomponenten. Die im Eurocode beschriebenen Bemessungsverfahren gelten nicht für diese Betonelemente.
Alle Gleisparameter, die bei der Bemessung von Gleis  und Weichenschwellen berücksichtigt werden müssen, sind in diesem Dokument im Einzelnen beschrieben. Es werden die erforderlichen Informationen zu diesen Parametern gegeben, sodass diese als Eingangswerte für das Bemessungsverfahren verwendet werden können. Es liegt in der Verantwortung des Kunden, alle in dieser Norm verwendeten Gleisparameter zu berechnen oder festzulegen.
Dieses Dokument enthält eine Anleitung für das Bemessungsverfahren. Sie legt dar, wie Betriebserfahrung und Rechenmodelle zur Festlegung von Bemessungskennwerten kombiniert werden können.
Dieses Dokument enthält Beispiele für Zahlenwerte, die bei Anwendung der Abschnitte 4 bis 6 in Übereinstimmung mit dem aktuellen Stand der Technik verwendet werden können.

Applications ferroviaires - Voie - Traverses et supports en béton - Partie 6 : Conception

Le présent document donne des recommandations de conception particulières dans les domaines suivants :
- la répartition des charges caractéristiques et des charges d'essai ;
- le calcul des moments de flexion caractéristiques et des moments de flexion d'essai.
L'objet du présent document est de formuler des recommandations pour la préparation de l'ensemble des données que l'acheteur doit remettre au fournisseur conformément aux Parties 1 à 5 de la série EN 13230. Il s'applique aux écartements de 1 000 mm, 1 435 mm et 1 668 mm, ainsi qu'à toutes les longueurs de traverses et supports.
Le présent document établit des critères spéciaux pour la conception de traverses et supports en béton en tant qu'éléments de voie. Les méthodes de conception figurant dans l'Eurocode ne s'appliquent pas à ces éléments en béton.
Tous les paramètres de voie à prendre en compte pour la conception des traverses et supports sont décrits dans le présent document. Le présent document fournit des informations concernant ces paramètres de sorte qu'ils puissent être utilisés comme données d'entrée pour le processus du calcul de conception. Il relève de la responsabilité de l'acheteur de calculer ou de déterminer tous les paramètres de voie utilisés dans le présent document.
Le présent document donne des recommandations pour le processus de calcul de conception. Elle explique comment les données empiriques et de calcul peuvent être combinées afin d'utiliser des paramètres de conception.
Le présent document donne des exemples de données numériques qui peuvent être utilisées lors de l'application des Articles 4 à 6 conformément à l'état de l'art.

Železniške naprave - Zgornji ustroj proge - Betonski pragi in kretniški betonski pragi - 6. del: Načrtovanje

General Information

• Status: Published
• Public Enquiry End Date: 30-Apr-2014
• Publication Date: 14-May-2020
• ICS: 45.080 - Rails and railway components
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: IŽNP - Reilway applications
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 12-May-2020
• Due Date: 17-Jul-2020
• Completion Date: 15-May-2020
• Directive: 2008/57/EC - Directive 2008/57/EC of the European Parliament and of the Council of 17 June 2008 on the interoperability of the rail system within the Community (Recast)
• Directive: 2016/797/EU - Directive (EU) 2016/797 of the European Parliament and of the Council of 11 May 2016 on the interoperability of the rail system within the European Union (Text with EEA relevance)
• Mandate: M/483 - Mandate for programming and standardisation addressed to the European standardisation bodies under directive 2008/57/EC in the field of the interoperability of the rail system within the European Union
• Ref Project: EN 13230-6:2020 - Railway applications - Track - Concrete sleepers and bearers - Part 6: Design

Overview - EN 13230-6:2020 (Concrete sleepers and bearers - Design)

EN 13230-6:2020 is the CEN European standard that provides design guidance for concrete sleepers and bearers used in railway track systems. It focuses on the derivation of characteristic loads and test loads and the calculation of characteristic and test bending moments. The standard applies to gauges 1 000 mm, 1 435 mm and 1 668 mm and to all sleeper and bearer lengths. It is intended to be used with Parts 1–5 of EN 13230 to form the contractual and technical basis between purchaser and supplier.

Key topics and technical requirements

• Load derivation
  • Methods for deriving characteristic wheel and rail-seat loads, dynamic increments and test load levels.
• Bending moment calculation
  • Procedures to calculate characteristic and test bending moments at the rail seat and centre sections for sleepers and for bearers.
• Design methods
  • Use of empirical, theoretical and combined approaches for bending-moment determination (Clauses 4.1 and 6).
• Track parameter inputs
  • Complete list and definition of track parameters required for design (track geometry, axle loads, speed, distribution of ballast reaction). The purchaser is responsible for determining these inputs.
• Special criteria for concrete track components
  • Notes that Eurocode design methods do not apply to these specific concrete elements; tailored criteria are provided instead.
• Durability, cracking and serviceability
  • Guidance on crack formation (rail seat and centre part), prestressing losses, and Serviceability Limit State checks for prestressed sleepers.
• Testing and acceptance
  • Factors for test loads, first-crack criteria, fatigue and exceptional/accidental loads.
• Annexes
  • Annex A: design methods, load factors and worked numerical examples.
  • Annex B: specific methods for turnout bearers.

Practical applications and users

Who uses EN 13230-6:2020:

• Track designers and structural engineers calculating sleeper/bearer resistance and fatigue.
• Infrastructure owners and purchasers preparing technical clauses and specifying required track parameters to suppliers.
• Manufacturers and suppliers sizing sleepers/bearers, preparing test plans and factory quality systems.
• Testing laboratories and acceptance teams verifying bending moments and first-crack loads.
• Maintenance and asset managers assessing lifecycle and durability implications.

Typical applications:

• Writing supplier contracts and technical specifications for concrete sleepers and bearers.
• Structural verification and test planning for new or modified sleeper designs.
• Ensuring compliance with EU Directive 2008/57/EC when combined with EN 13230 Parts 1–5.

Related standards

• EN 13230 series (Parts 1–5): General requirements, prestressed monoblock, twin-block, bearers for S&C, special elements.
• EN 13146-3, EN 13146-5: Test methods for fastening systems.
• Informative link to EU Directive 2008/57/EC (Annex ZA).

Keywords: EN 13230-6:2020, concrete sleepers, bearers, railway design, bending moments, characteristic loads, test loads, track components, purchaser, supplier.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2020
Železniške naprave - Zgornji ustroj proge - Betonski pragi in kretniški betonski
pragi - 6. del: Načrtovanje
Railway applications - Track - Concrete sleepers and bearers - Part 6: Design
Bahnanwendungen - Oberbau - Gleis- und Weichenschwellen aus Beton - Teil 6:
Entwurf
Applications ferroviaires - Voie - Traverses et supports en béton - Partie 6 : Conception
Ta slovenski standard je istoveten z: EN 13230-6:2020
ICS:
45.080 Tračnice in železniški deli Rails and railway
components
91.100.30 Beton in betonski izdelki Concrete and concrete
products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 13230-6
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2020
EUROPÄISCHE NORM
ICS 91.100.30; 93.100
English Version
Railway applications - Track - Concrete sleepers and
bearers - Part 6: Design
Applications ferroviaires - Voie - Traverses et supports Bahnanwendungen - Oberbau - Gleis- und
en béton - Partie 6 : Conception Weichenschwellen aus Beton - Teil 6: Bemessung
This European Standard was approved by CEN on 8 April 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

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. EN 13230-6:2020 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and symbols . 6
4 General requirements . 9
4.1 General process for determination of bending moments . 9
4.1.1 General . 9
4.1.2 Empirical method . 9
4.1.3 Theoretical method . 10
4.1.4 Combined method . 11
4.2 Crack formation in concrete sleepers or bearers . 11
4.2.1 Cracks under rail seat . 11
4.2.2 Cracks at centre part (prestressed monoblock sleepers or bearers) . 12
4.2.3 Cracks for tests for negative bending under rail seat or positive bending at centre
part . 12
4.3 Section design of sleeper . 12
4.4 Durability of sleeper . 12
5 Design parameters . 12
5.1 Maintenance . 12
5.1.1 Track and rolling stock quality . 12
5.1.2 Distribution of the vertical load in the longitudinal direction . 13
5.1.3 Distribution of ballast reaction along the length of the sleeper . 13
5.2 Track laying conditions . 13
5.2.1 Mass of sleeper . 13
5.2.2 Length of sleeper . 13
5.2.3 Depth of sleeper . 13
5.2.4 Track installation methods . 13
5.3 Track components design . 14
5.3.1 Rail profile and sleeper spacing . 14
5.3.2 Fastening system . 14
5.3.3 Track stability . 14
5.4 Impact of traffic characteristics and track alignment . 15
5.4.1 Axle load . 15
5.4.2 Maximum speed . 15
5.4.3 Curving load . 15
6 Design method . 15
6.1 Specific aspects for design and testing . 15
6.1.1 Railway experience for exceptional or accidental impact loads. 15
6.1.2 Flexural tensile strength of concrete . 15
6.1.3 Losses of prestressing . 16
6.1.4 Experience for track work . 16
6.2 Design calculation . 16
6.2.1 General . 16
6.2.2 Calculation of dynamic rail seat load P under normal service conditions . 16
k
6.2.3 Calculation of the characteristic bending moments for rail seat of sleepers . 16
6.2.4 Calculation of the characteristic bending moments for centre part of sleepers . 17
6.2.5 Calculation of the characteristic bending moments for bearers . 18
6.2.6 Checking of stresses in concrete . 18
6.2.7 Determination of test bending moments for first crack formation. 18
Annex A (informative) Design methods and factors for sleepers . 20
A.1 General . 20
A.1.1 Introduction . 20
A.1.2 Determination of characteristic bending moments . 20
A.1.3 Load levels and corresponding bending moments . 21
A.2 Rail seat load . 22
A.2.1 Normal service increment for the dynamic wheel load . 22
A.2.2 Distribution of vertical loads in longitudinal direction . 22
A.2.3 Effects of elastic rail pads . 25
A.2.4 Calculation of dynamic rail seat load . 25
A.3 Characteristic bending moments . 25
A.3.1 General . 25
A.3.2 Rail seat section. 26
A.3.3 Sleeper centre section . 27
A.4 Factors for test loads and acceptance criteria . 33
A.4.1 General . 33
A.4.2 Factor for first crack formation . 33
A.4.3 Factors for exceptional loads . 34
A.4.4 Factors for accidental loads . 35
A.4.5 Factor for fatigue test . 35
A.5 Checking of stresses for Serviceability Limit State (for prestressed sleepers only) . 35
A.6 Design examples . 36
A.6.1 General . 36
A.6.2 Example 1: 1 435 mm gauge waisted sleeper with elastic beam on elastic foundation
calculation . 38
A.6.3 Example 2: 1 435 mm gauge rectangular sleeper using simplified method . 46
A.6.4 Example 3: 1 668 mm gauge waisted sleeper . 52
Annex B (informative) Design methods and factors for turnout bearers . 56
Annex ZA (informative) Relationship between this European standard and the Essential
Requirements of EU Directive 2008/57/EC aimed to be covered . 59
Bibliography . 61

European foreword
This document (EN 13230-6:2020) has been prepared by Technical Committee CEN/TC 256 “Railway
applications”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2020, and conflicting national standards shall
be withdrawn at the latest by October 2020.
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 a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive 2008/57/EC.
For relationship with EU Directive 2008/57/EC, see informative Annex ZA, which is an integral part of
this document.
This European Standard is one of the EN 13230 series, Railway applications – Track – Concrete sleepers
and bearers, which consist of the following parts:
— Part 1: General requirements;
— Part 2: Prestressed monoblock sleepers;
— Part 3: Twin-block reinforced sleepers;
— Part 4: Prestressed bearers for switches and crossings;
— Part 5: Special elements;
— Part 6: Design.
This European Standard can be used as a technical basis between contracting parties (purchaser –
supplier).
Annexes A and B are informative; they can be used as normative requirements by completion of a
contract, if agreed by the contracting parties.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Introduction
This document covers the design of concrete sleepers and bearers and is used in conjunction with the
following parts:
— Part 1: General requirements;
— Part 2: Prestressed monoblock sleepers;
— Part 3: Twin-block reinforced sleepers;
— Part 4: Prestressed bearers for switches and crossings;
— Part 5: Special elements.
Concrete sleepers and bearers are safety critical components for railway applications. They are not
covered by any other European Standard.
As safety critical components, an agreement is needed between purchaser and supplier to operate a
factory Quality System.
1 Scope
This document provides particular design guidance in the following areas:
— derivation of characteristic loads and test loads;
— calculation of characteristic and test bending moments.
The aim of this document is to give guidance for the preparation of all data to be given by the purchaser
to the supplier in accordance with Parts 1 to 5 of EN 13230. It applies to gauges 1 000 mm, 1 435 mm,
1 668 mm as well as to all lengths of sleepers and bearers.
This document gives special criteria for the design of concrete sleepers and bearers as track
components. The design methods in the Eurocode do not apply to these concrete elements.
All track parameters to be taken into account for the design of sleepers and bearers are detailed in this
document. Information is given on these parameters so that they can be used as inputs for the design
calculation process. It is the responsibility of the purchaser to calculate or determine all track
parameters used in this document.
This document gives guidance for the design calculation process. It explains how experience and
calculation can be combined to use design parameters.
This document gives examples of numerical data that can be used when applying Clauses 4 to 6
according to the state of the art.
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 13146-3, Railway applications – Track – Test methods for fastening systems – Part 3: Determination of
attenuation of impact loads
EN 13146-5, Railway applications – Track – Test methods for fastening systems – Part 5: Determination of
electrical resistance
EN 13146-10, Railway applications – Track – Test methods for fastening systems – Part 10: Proof load test
for pull-out resistance
EN 13230-1:2016, Railway applications – Track – Concrete sleepers and bearers – Part 1: General
requirements
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in EN 13230-1:2016 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
nominal axle load
A
nom
axle load from nominal weight of rolling stock
3.2
nominal wheel load
Q
nom
static vertical wheel load resulting from nominal axle load
3.3
characteristic wheel load
Q
k
characteristic value of the vertical wheel load
3.4
factor k
p
factor used for rail pad attenuation
3.5
factor kv
factor used for the effect of speed
3.6
factor k
d
factor used for longitudinal distribution of vertical load between sleepers
3.7
factor k
r
factor used for variations of the longitudinal load distribution between sleepers due to support faults
3.8
factor k
i,r
factor used for calculation of characteristic bending moments at rail seat due to irregularities in the
support along the length of the sleeper
3.9
factor k
i,c
factor used for calculation of characteristic bending moments at centre section due to irregularities in
the support along the length of the sleeper
3.10
internal lever arm
λ
internal lever arm of the forces and ballast reaction acting on the sleeper at the rail seat section
3.11
exceptional load
load that occurs only a few times in the life of sleeper
3.12
accidental load
load that occurs only once in the life of a sleeper
3.13
factor k
t
factor used for the calculation of acceptance criteria for first crack formation in static tests
3.14
dynamic rail seat load
P
k
characteristic load on a rail seat of the sleeper for normal service dynamic loading
3.15
characteristic bending moment
M
k
bending moment from dynamic rail seat load P
k
3.16
characteristic positive bending moment for rail seat section
M
k,r,pos
positive bending moment at rail seat from dynamic rail seat load P
k
3.17
characteristic negative bending moment for rail seat section
M
k,r,neg
negative bending moment at rail seat from dynamic rail seat load P
k
3.18
characteristic negative bending moment for centre section
M
k,c,neg
negative bending moment at centre section from dynamic rail seat load P
k
3.19
characteristic positive bending moment for centre section
M
k,c,pos
positive bending moment at centre section from dynamic rail seat load P
k
3.20
test bending moment
M
t
test bending moment for first crack formation derived from characteristic bending moment
3.21
positive test bending moment for rail seat section
M
t,r,pos
positive test bending moment for first crack formation at rail seat derived from the characteristic
bending moment
3.22
negative test bending moment for rail seat section
M
t,r,neg
negative test bending moment for first crack formation at rail seat derived from the characteristic
bending moment
3.23
negative test bending moment for centre section
M
t,c,neg
negative test bending moment for first crack formation at centre section derived from the characteristic
bending moment
3.24
positive test bending moment for centre section
M
t,c,pos
positive test bending moment for first crack formation at centre section derived from the characteristic
bending moment
3.25
factor k
factor used for calculation of test bending moments which is due to exceptional and random impact
load, which is applied to characteristic bending moments and which is k for dynamic test and k for
1d 1s
static test
3.26
factor k2
factor which is used for calculation of test bending moments due to accidental impact load, which is
applied to characteristic bending moments and which is k for dynamic test and k for static test
2d 2s
3.27
factor k
factor which is used for calculation of fatigue test bending moments and which is applied to
characteristic bending moments
4 General requirements
4.1 General process for determination of bending moments
4.1.1 General
The track is an assembly of transverse concrete sleepers or bearers secured to the rails by means of a
fastening system and supported by ballast or other support. It is characterized by the gauge of the track,
the rail profile, the inclination of the rails and the spacing of the concrete sleepers and bearers. The
assembly including the rail, the fastening system and concrete sleepers or bearers on ballast or other
support may be considered as a beam on an elastic foundation.
The determination of bending moments in sleepers and bearers laid on ballast for the service
conditions may be obtained using the three following different approaches.
4.1.2 Empirical method
In the empirical method appropriate sleepers or bearers are tested in track under service conditions.
Deficiency from tested sleepers/bearers can lead to step wise improvement of the sleeper/bearer
design. The results shall be confirmed by permanent observation during at least five years. The
characteristic bending moments shall be determined by measurements in track. The number of the test
samples shall be sufficient to give statistically reliable results.
The characteristic bending moment may also be determined by means of bending tests according to the
EN 13230 series using sleepers that have been in service for five years at least. The test bending
moment that produces the first crack formation shall be in accordance with EN 13230-1:2016, 7.2.
Figure 1 details steps for the determination of characteristic bending moments for prestressed concrete
sleepers. In this figure, new sleeper means a sleeper with geometry similar to the existing one.
For twin block concrete sleepers and bearers the same methodology shall be used.

Figure 1 — Empirical method for design of prestressed concrete sleepers
NOTE Taking the test loads Fr , Fc and Fc of the existing sleeper as initial reference test loads for a new
r r rn
sleeper normally will lead to characteristic bending moments lying on the safe side. The assumption that all losses
of prestress and strength have taken place may be correct for an exposition to traffic loads for at least 5 years.
In order to get more information about the load carrying capacity of the existing sleeper, additional
tests for inverse bending moments at the rail seat and dynamic tests at sleeper centre may be carried
out.
4.1.3 Theoretical method
The theoretical method shall be based on design procedures considering the dynamic load, the elastic
behaviour of all track components including all types of elastic pads, the variable ballast-subsoil
elasticity and the different ballast consolidation phases.
Figure 2 details steps for the determination of bending moments for prestressed concrete sleepers. For
twin block concrete sleepers and bearers the same methodology shall be used.

Figure 2 — Theoretical method for design of prestressed concrete sleepers
4.1.4 Combined method
The combined method includes empirical and theoretical elements leading to a shorter product
development time.
4.2 Crack formation in concrete sleepers or bearers
4.2.1 Cracks under rail seat
Wheel loads generate positive and negative bending moments under the rail seat.
The bending resistance at the end of the required service life time under the rail seat is determined by
the characteristic bending moment.
When subjected to the static test bending moment, there shall be no first crack at the tensile face of the
prestressed concrete sleeper or bearer, see EN 13230-1:2016, 7.2.
The second stage of the test bending moment to be defined is the bending moment due to exceptional
and random impact loads. It is calculated by multiplying the positive characteristic bending moment
M by coefficient k . Any crack produced by this bending moment shall close (crack width below
k,r,pos 1
0,05 mm) upon removal of the bending moment. Exceptional bending moments occur only a few times
in the lifetime of a concrete sleeper and bearer.
The third stage of the test bending moment is the ultimate bending moment due to accidental impacts,
calculated by multiplying the positive characteristic bending moment M by coefficient k .
k,r,pos 2
4.2.2 Cracks at centre part (prestressed monoblock sleepers or bearers)
Wheel loads generate positive and negative bending over the central length of the sleeper.
The required flexural strength over the central part of the sleeper is determined from the bending
moment induced by the dynamic rail seat load and depends on the distribution of the ballast reaction.
When subjected to the negative static test bending moment, there shall be no first crack at the tensile
face of the concrete sleeper or bearer as required in EN 13230-1:2016, 7.2.
If permitted by the purchaser, controlled cracking of sleepers or bearers in track can be accepted. In
that case, residual crack opening and fatigue shall be checked according to method agreed by the
purchaser.
4.2.3 Cracks for tests for negative bending under rail seat or positive bending at centre part
Additional bending tests with crack measurement can be required to check the general design or
manufacture of the sleeper or for specific loads imposed during track installation.
4.3 Section design of sleeper
The section design shall follow prescriptions of EN 13230-1:2016, Clause 6.
4.4 Durability of sleeper
Requirements for providing durability are included in EN 13230-1.
5 Design parameters
5.1 Maintenance
5.1.1 Track and rolling stock quality
The maintenance policy for both track and rolling stock will influence the loads imposed on the track.
Track geometry quality should be according to EN 13848-1 and EN 13848-5 and rolling stock
maintenance policies will define the maximum tolerance for wheel flats and their out of roundness.
These criteria together with maximum train speed shall be taken into account by the purchaser to
determine:
— the dynamic rail seat load;
— the impact factor for exceptional loads;
— the characteristic bending moments and test bending moments.
5.1.2 Distribution of the vertical load in the longitudinal direction
The distribution of the wheel load over adjacent sleepers along the track depends on the vertical
bending stiffness of the rail, sleeper spacing, rail pad stiffness and the stiffness of ballast or subsoil.
Factor kd can be determined applying the “elastic beam on elastic foundation” theory with a constant
bedding modulus along the rail.
In addition, factor k represents the variation of the sleeper reaction in the ballast due to longitudinal
r
supports faults along the track. This factor should be evaluated by measurements in track.
It is the responsibility of the purchaser to determine the coefficients k and k .
d r
Recommendations for factors k and k are given in Annex A.
d r
5.1.3 Distribution of ballast reaction along the length of the sleeper
The length and the width of the sleeper can influence the effective stiffness reaction of the ballast and
the longitudinal distribution of wheel load along the length of the sleeper. Moreover variation in ballast
reaction can be caused by characteristic of sub grade under ballast, by variation of ballast stiffness due
to tamping or freezing, or by ballast quality (size of ballast, stone characteristics and fouling of ballast
layer).
When uniform ballast reaction or bedding modulus are assumed, load distribution may be changed
considerably in track due to the random formation of local load contact points within the ballast. The
difference between the bending moments calculated with a simplified design model and the
characteristic bending moments measured in track shall be taken into account by factors ki,r at rail seat
for bending moment increase at the centre.
section or ki,c
It is the responsibility of the purchaser to determine the coefficients k and k .
i,r i,c
Recommendations for factors k and k are given in Annex A.
i,r i,c
5.2 Track laying conditions
5.2.1 Mass of sleeper
The mass of sleeper contributes to lateral resistance of track. Transportation to work site and track
installation methods can determine the maximum mass.
5.2.2 Length of sleeper
The length of sleeper contributes to longitudinal and lateral distribution of ballast reaction.
Transportation to work site and track installation methods can determine the maximum length.
5.2.3 Depth of sleeper
Depth of sleeper contributes to section modulus of sleepers and to longitudinal and lateral resistance of
track. Transportation to work site, available overhead clearances and track installation methods can
determine the depth.
5.2.4 Track installation methods
During track installation, loadings may occur which are different from those that occur from the
operation of regular service trains. Care should be taken that there is no excessive bending of the
concrete sleeper.
5.3 Track components design
5.3.1 Rail profile and sleeper spacing
An individual sleeper will only take a proportion of the wheel load as some will be shared with adjacent
sleepers.
The factor k for load distribution between sleepers takes into account distribution of longitudinal loads
d
as described in 5.1.2. Recommendations for factor k according to rail profile and sleeper spacing are
d
given in Annex A.
5.3.2 Fastening system
NOTE EN 13481-2 defines requirements for fastening system to be used for concrete sleepers.
5.3.2.1 Attenuation of impact loads by fastening system
The type of rail pad shall be taken into account when choosing the impact attenuation factor k .
p
EN 13146-3 evaluates the impact attenuation a of fastening systems by means of a test to measure the
magnitude of impact bending strains in a concrete sleeper.
An impact attenuation factor k may be used for calculation of characteristic loads. However, it is
p
recommended to reduce the attenuation value measured for the fastening system by 25 % in the
normal case to allow for the service condition. In order to adopt the reductions that may be made in the
design load by accounting for the use of resilient rail pads, the purchaser will need to ensure that
maintenance standards ensure the continuous use of rail pads equivalent to or better than those
assumed in the design.
It is the responsibility of the purchaser to determine the coefficient k .
p
Recommendations for factor k are given in Annex A.
p
5.3.2.2 Vertical stiffness of fastening system
The vertical stiffness of fastening system contributes to track stiffness and shall be considered when
choosing factors k and k .
d p
5.3.2.3 Electrical insulation
EN 13146-5 defines method and arrangement for the determination of electrical resistance.
5.3.2.4 Vertical load test for cast-in fastening components
EN 13146-10 defines requirements for load test for cast-in fastening components.
5.3.3 Track stability
5.3.3.1 Lateral resistance of sleeper in ballast
The lateral stability of track depends on dimensions of the sleeper (and in particular the mass) and the
transverse ballast profiles. The design of the sleeper shall be in accordance with the purchaser’s rules
for continuous welded rails.
5.3.3.2 Longitudinal resistance of sleeper in ballast
The dimensions of the sleeper (especially the mass) in combination with transverse ballast profiles
influence the longitudinal resistance of sleeper and will require special consideration for transition
zones at continuous welded rails ends, bridge ends or rail profile changes.
5.4 Impact of traffic characteristics and track alignment
5.4.1 Axle load
Effects of rolling stock on sleepers are based upon the nominal axle load (A ) of trains. As the sleeper
nom
design load will be expressed per wheel, the static part of vertical wheel load can be determined
directly from the nominal axle load.
5.4.2 Maximum speed
The maximum speed shall be taken into account for choosing the normal service dynamic factor k .
v
See Annex A for recommendations concerning the factor k .
v
5.4.3 Curving load
The dynamic rail seat load shall take into account:
— the quasi-static increase of vertical wheel load on rails due to cant deficiency or excess;
— the lateral force of wheel which can also induce an additional bending moment in the sleeper.
Both effects can be included in normal service dynamic factor k .
v
It is the responsibility of the purchaser to determine the coefficient k .
v
See Annex A for recommendations concerning the factor k .
v
6 Design method
6.1 Specific aspects for design and testing
6.1.1 Railway experience for exceptional or accidental impact loads
Exceptional impact loads (which can occur few times in a sleeper lifetime) from:
— large wheel flats;
— large rail defects;
create bending moments higher than the characteristic bending moment.
In order to take into account these exceptional impact loads, the characteristic bending moment shall be
multiplied by a dynamic and static factor k1 when calculating the acceptance criteria for testing in
accordance of EN 13230-1:2016, Clauses 7 and 8.
In order to take into account these accidental impact loads, the characteristic bending moment shall be
multiplied by a dynamic and static factor k when calculating the acceptance criteria for testing in
accordance of EN 13230-1:2016, Clauses 7 and 8.
The purchaser shall state the dynamic and static factor k and k . See Annex A for recommendations for
1 2
factors k and k .
1 2
6.1.2 Flexural tensile strength of concrete
The flexural tensile strength of concrete shall be considered on short-term and on fatigue level.
Recommendations for flexural tensile strength of concrete are given in Annex A.
6.1.3 Losses of prestressing
There is loss of prestressing depending on time, service conditions and production method.
Loss of prestressing shall be taken into account for acceptance tests, routine tests and checking stresses
in concrete.
Recommendations concerning loss of prestressing are given in Annex A.
6.1.4 Experience for track work
Track laying conditions and maintenance (tamping) can lead to various load distribution cases at the
sleeper bottom surface.
6.2 Design calculation
6.2.1 General
The analysis and structural design of the concrete sleeper shall be based upon the derivation of bending
moments at least at the rail seat section and at the sleeper centre. The calculation of bending moments
due to traffic loads under normal service conditions is based on the elastic behaviour of the track.
6.2.2 Calculation of dynamic rail seat load P under normal service conditions
k
The dynamic rail seat load, used to derive the characteristic bending moment, can be calculated
according to Formula (1):
A
nom
(1)
P (1+ kk× )××kk
k pv d r
6.2.3 Calculation of the characteristic bending moments for rail seat of sleepers
The bending moment at the rail seat is influenced by the ballast reaction, the width of the rail foot and
the geometry of the sleeper.
The sleeper may be regarded as an “elastic beam on elastic foundation”. The calculation of the
characteristic bending moments can be performed with the use of:
a) reference method based on an elastic beam model resting on local elastic support under rail seat;
b) a simplified method based on assumption of constant ballast pressure under rail seat.
Stages of the calculation and input data for both methods are described in the flowchart in Figure 3.
An example for calculation of characteristic bending moments is given in Annex A.
=
Figure 3 — Stages of the calculation and input data at rail seat section
6.2.4 Calculation of the characteristic bending moments for centre part of sleepers
The sleeper may be regarded as an “elastic beam on elastic foundation”.
Two alternative methods are detailed in Annex A:
a) Reference method based on a complete elastic beam model;
b) A simplified method based on pre calculated curves based on calculation from “Beam on elastic
foundation”.
Stages of the calculation and input data for both methods are described in the flowchart in Figure 4.
Figure 4 — Stages of the calculation and input data at centre section
An example for calculation of characteristic bending moments is given in Annex A.
6.2.5 Calculation of the characteristic bending moments for bearers
Due to various length and position of rail seats, characteristic bending moments cannot be simply
calculated.
Positive and negative test bending moments shall be defined by the purchaser (examples are given in
Annex B).
6.2.6 Checking of stresses in concrete
The maximum flexural tensile stress in concrete due to the characteristic bending moment shall be
lower than the fatigue flexural tensile strength f of the concrete. This condition is fulfilled by the use
ct,fl,fat
of factor k .
t
If maximum compressive stress is to be checked for fatigue life, agreement between the supplier and
the purchaser shall be set. Recommendations for flexural strength of concrete are given in Annex A.
6.2.7 Determination of test bending moments for first crack formation
6.2.7.1 Prestressed sleepers and bearers
The flexural behaviour of a prestressed concrete sleeper or bearer depends essentially on the section
modulus, the prestressing force and the flexural concrete strength. Latest two parameters change
during the lifetime of the sleeper or bearer.
The initial prestressing force decreases due to elastic shortening of the sleeper, steel relaxation, creep
and shrinkage of the concrete, towards a final value. Recommendations for determination loss of
prestressing are given in Annex A.
The flexural tensile strength increases within the first weeks after production. During the following
service life a continued loss of flexural strength may appear due to fatigue by repeated wheel loads.
Both effects, together, lead to the flexural strength varying with time. The bending moments initiating
first crack for sleepers and bearers after a short time are considerably higher than the required
characteristic moments M .
k
The characteristic bending moment M should therefore be increased by the coefficient k for the
k t
calculation of static test bending moment M taking into account the age of the sleeper during testing.
t
The increased test bending moment including the time depending losses is:
M kM×
(2)
tt k
It is the responsibility of the purchaser to determine the coefficient k .
t
Recommendations for factor kt are given in Annex A.
An example of calculation of static test bending moments is given in Annex A.
6.2.7.2 Reinforced concrete sleepers
First crack formation is not a design criterion for reinforced concrete sleepers.
=
Annex A
(informative)
Design methods and factors for sleepers
A.1 General
A.1.1 Introduction
The design principle of using simple beam models combined with factors obtained by track
measurements has already been established in ORE D71 and further developed in ORE D170 and
UIC 713. Methods and factors presented in this Annex follow the same rules and in general can be
applied to any track gauges. The designation of values such as loads, bending moments and factors
however has been adapted to the actual state of art and use of symbols in Eurocod
...