DD CEN/TS1992-4-3:2009

ICS 21.060.01; 91.080.40

NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW

DRAFT FOR DEVELOPMENT

Design of fasteningsfor use in concretePart 4-3: Anchor channels

This Draft for Developmentwas published under theauthority of the StandardsPolicy and StrategyCommittee on 30 June2009.© BSI 2009

ISBN 978 0 580 62637 1

Amendments/corrigenda issued since publication

Date Comments

DD CEN/TS 1992-4-3:2009

National foreword

This Draft for Development is the UK implementation of CEN/TS1992-4-3:2009.This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development series of publications andis of a provisional nature. It should be applied on this provisional basis,so that information and experience of its practical application can beobtained.Comments arising from the use of this Draft for Development arerequested so that UK experience can be reported to the internationalorganization responsible for its conversion to an international standard.A review of this publication will be initiated not later than 3 years afterits publication by the international organization so that a decision can betaken on its status. Notification of the start of the review period will bemade in an announcement in the appropriate issue of Update Standards.

According to the replies received by the end of the review period,the responsible BSI Committee will decide whether to support theconversion into an international Standard, to extend the life of theTechnical Specification or to withdraw it. Comments should be sent tothe Secretary of the responsible BSI Technical Committee at BritishStandards House, 389 Chiswick High Road, London W4 4AL.The UK participation in its preparation was entrusted to TechnicalCommittee B/525/2, Structural use of concrete.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.

DD CEN/TS 1992-4-3:2009

TECHNICAL SPECIFICATION

SPÉCIFICATION TECHNIQUE

TECHNISCHE SPEZIFIKATION

CEN/TS 1992-4-3

May 2009

ICS 21.060.01; 91.080.40

English Version

Design of fastenings for use in concrete - Part 4-3: Anchorchannels

Conception-calcul des éléments de fixation pour béton -Partie 4-3 : Rails d'ancrage

Bemessung von Befestigungen in Beton - Teil 4-3:Ankerschienen

This Technical Specification (CEN/TS) was approved by CEN on 20 October 2008 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 theircomments, 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 availablepromptly 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, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATIONC O M I T É E U R O P É E N D E N O R M A LI S A T I O NEUR OP ÄIS C HES KOM ITEE FÜR NOR M UNG

Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2009 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.

Ref. No. CEN/TS 1992-4-3:2009: E

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Contents Page

Foreword ..............................................................................................................................................................3

1 Scope ......................................................................................................................................................41.1 General ....................................................................................................................................................41.4 Anchor channel loading ........................................................................................................................41.4.3 Actions not covered ..............................................................................................................................4

2 Normative references ............................................................................................................................4

3 Definitions and symbols .......................................................................................................................5

4 Basis of design ......................................................................................................................................5

5 Determination of action effects ............................................................................................................55.2 Derivation of forces acting on anchor channels ................................................................................55.2.1 General ....................................................................................................................................................55.2.2 Tension loads .........................................................................................................................................65.2.3 Shear loads .............................................................................................................................................75.3 Tension forces in a supplementary reinforcement ............................................................................85.3.3 Tension loads .........................................................................................................................................85.3.4 Shear loads .............................................................................................................................................8

6 Verification of ultimate limit state by elastic analysis .......................................................................96.1 General ....................................................................................................................................................96.2 Tension loads .........................................................................................................................................96.2.1 Required verifications ...........................................................................................................................96.2.2 Design of supplementary reinforcement .............................................................................................96.2.3 Steel failure .......................................................................................................................................... 116.2.4 Pullout failure ...................................................................................................................................... 116.2.5 Concrete cone failure ......................................................................................................................... 126.2.6 Splitting failure .................................................................................................................................... 166.2.7 Blow-out failure ................................................................................................................................... 176.2.8 Steel failure of the supplementary reinforcement ........................................................................... 186.2.9 Anchorage failure of the supplementary reinforcement in the concrete cone ............................ 196.3 Shear loads .......................................................................................................................................... 196.3.1 Required verifications ........................................................................................................................ 196.3.2 Design of reinforcement .................................................................................................................... 196.3.3 Steel failure .......................................................................................................................................... 216.3.4 Concrete pry-out failure ..................................................................................................................... 226.3.5 Concrete edge failure ......................................................................................................................... 226.3.6 Steel failure of supplementary reinforcement ................................................................................. 266.3.7 Anchorage failure of supplementary reinforcement in the concrete cone ................................... 266.4 Combined tension and shear loads .................................................................................................. 276.4.1 Anchor channels without supplementary reinforcement ............................................................... 276.4.2 Anchor channels with supplementary reinforcement..................................................................... 27

7 Fatigue ................................................................................................................................................. 28

8 Seismic ................................................................................................................................................ 28

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Foreword

This Technical Specification (CEN/TS 1992-4-3:2009) has been prepared by Technical Committee CEN/TC 250 “Structural Eurocodes”, the secretariat of which is held by BSI.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

This Technical Specification CEN/TS 1992-4- 3 — Anchor Channels, describes the principles and requirements for safety, serviceability and durability of anchor channels for use in concrete, together with specific provisions for structures serving as base material. It is based on the limit state concept used in conjunction with a partial factor method.

This Technical Specification does not provide information about the use of National Determined Parameters (NDP).

CEN/TS 1992-4 'Design of fastenings for use in concrete' is subdivided into the following parts:

Part 1: General

Part 2: Headed fasteners

Part 3: Anchor channels

Part 4: Post-installed fasteners — Mechanical systems

Part 5: Post-installed fasteners — Chemical systems

Relation to CEN/TS 1992-4-1

The principles and requirements of Part 3 of this CEN/TS are additional to those in CEN/TS 1992-4-1, all the clauses and sub-clauses of which also apply to Part 3 unless varied in this Part. Additional information is presented under the relevant clauses/sub-clauses of CEN/TS 1992-4-1. The numbers for the clauses/sub-clauses of Part 3 continue from the number of the last relevant clauses/sub-clauses of Part 1.

The above principles also apply to Figures and Tables in Part 3.

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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.

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1 Scope

1.1 General

1.1.6 This document relies on characteristic resistances and distances which are stated in a European Technical Specification. In minimum the following characteristics should be given in a European Technical Specification as base for the design methods of this CEN/TS.

as,Rk,N , cs,Rk,N , ls,Rk,N , ss,Rk,N , ss,Rk,V , ls,Rk,V , flexs,Rk,M , 0sRk,M

NRk,p

pch,αα

ccr,N, scr,N

ccr,sp, scr,sp

cmin, smin, hmin

limitations on concrete strength classes of base material

k5

Ah, bch, d, hef, hch, Iy

γMi partial factors for material see also CEN/TS 1992-4-1:2009, clause 4

1.4 Anchor channel loading

1.4.3 Actions not covered

The following actions are not covered by this CEN/TC:

shear in the direction of the longitudinal axis of the channel;

fatigue loading;

seismic loading.

2 Normative references

This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies.

NOTE The following references to Eurocodes are references to European Standards and European Prestandards. These are the only European documents available at the time of publication of this TS. National documents take precedence until Eurocodes are published as European Standards.

EN 1992-1-1, Design of concrete structures — Part 1-1: General rules and rules for buildings

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CEN/TS 1992-4-1:2009, Design of fastenings for use in concrete — Part 4-1: General

3 Definitions and symbols

The definitions and symbols are given in CEN/TS 1992-4-1.

4 Basis of design

4.5.4 The following assumptions in respect to installation have been made in this CEN/TS. The installation instructions should reflect them:

1) The anchor channel should be fixed to the formwork or auxiliary constructions in a way that no movement of the anchor channel will occur during placing of reinforcement or during pouring and compacting of the concrete.

2) Requirements for adequate compaction particularly under the head of the anchor and under the channel.

3) Requirements for inspection and approval of the correct installation of the anchor channels by appropriately qualified personnel.

4) Placing anchor channels by only pushing them into the wet concrete is not allowed.

5) It is accepted to vibrate the anchor channels into the wet concrete immediately after pouring under the following conditions:

The size and number of fastenings is limited to anchor channels with a length of <1 m if placed by 1 person, so that it can be placed simultaneously during vibrating by the available personnel. Longer channels should be placed by at least 2 persons.

The installation is carried out according to a quality system.

The anchor channels are not moved after vibrating has been finished.

The concrete in the region of the anchor and the anchor channel is properly compacted.

5 Determination of action effects

5.2 Derivation of forces acting on anchor channels

5.2.1 General

5.2.1.6 The distribution of tension loads acting on the channel to the anchors may be calculated using a beam on elastic support (anchors) with a partial restraint of the channel ends as statical system. The resulting anchor forces depend significantly on the assumed anchor stiffness and degree of restraint. For shear loads the load distribution is also influenced by the pressure distribution in the contact zone between channel and concrete.

5.2.1.7 As a simplification for anchor channels with two anchors the loads on the anchors may be calculated assuming a simply supported beam with a span length equal to the anchor spacing.

5.2.1.8 For anchor channels with more than two anchors as an alternative in the following the triangular load distribution method to calculate the distribution of tension and shear loads to the anchors is introduced.

5.2.1.9 In the case of shear loads, this CEN/TS covers only shear loads acting on the channel perpendicular to its longitudinal axis.

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5.2.2 Tension loads

5.2.2.1 This clause supersedes CEN/TS 1992-4-1:2009, 5.5.2.

5.2.2.2 The tension forces in each anchor due to a tension load acting on the channel are calculated according to Equation (1), which assumes a linear load distribution over the influence length li and takes into account the condition of equilibrium. The influence length li shall be calculated according to Equation (3). An example for the calculation of the forces acting on the anchors is given in Figure 1.

Ed'iiEd, NAk ⋅⋅=aN (1)

with

'iA ordinate at the position of the anchor i of a triangle with the unit height at the position of load N and

the base length 2li

∑=

nA

k

1i'

1 (2)

[mm]13 0,50,05yi ssIl ≥⋅⋅= (3)

n number of anchors on the channel within the influence length Ii to either side of the applied load NEd (see Figure 1)

Iy moment of inertia of the channel [mm4], see Figure 3.2

s anchor spacing [mm]

The moment of inertia of the channel should be taken from the relevant European Technical Specification.

If several tension loads are acting on the channel a linear superimposition of the anchor forces for all loads should be assumed.

If the exact position of the load on the channel is not known, the most unfavourable loading position should be assumed for each failure mode (e.g. load acting over an anchor for the case of failure of an anchor by steel rupture or pull-out and load acting between anchors in the case of bending failure of the channel).

The bending moment in the channel due to tension loads acting on the channel may be calculated assuming a simply supported single span beam with a span length equal to the anchor spacing.

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611,25'

2 =−=l

slA 0aEd

aEd == 51 ,, NN

650,25'

3 =−=l

slA EdaEd NNN , 9

132

61

2 =⋅⋅=

210,75'

4 =−=l

slA Eda

3Ed NNN , 95

32

65 =⋅⋅=

321

'4

'3

'2

=++

=AAA

k EdaEd,4 3

132

21 NNN =⋅⋅=

Figure 1 — Example for the calculation of anchor forces according to the triangular load distribution method for an anchor channel with 5 anchors - the influence length is assumed as li = 1,5s

NOTE The assumption of a simply supported beam to calculate the moments is a simplification which neglects the influence of partial end restraints, continuous beam action for channels with more than 2 anchors and catenary action after yielding of the channel. The characteristic values of the moments of the resistance given in the European Technical Specification take these effects into account. They may be larger than the plastic moment, calculated with the dimensions of the channel and nominal yield strength of the steel.

5.2.3 Shear loads

5.2.3.1 Section 5.2.3.2 supersedes CEN/TS 1992-4-1:2009, 5.2.3.1. The provisions given in CEN/TS 1992-4-1:2009, 5.2.3.2 and 5.2.3.3 should be used to determine whether a shear load acts with or without a lever arm on the special screw.

5.2.3.2 The shear forces of each anchor due to a shear load acting on the channel perpendicular to its longitudinal axis may be calculated as described in 5.2.2.

NOTE Shear loads applied perpendicular to anchor channels are transferred by compression stresses in the interface between channel and concrete mainly directly into the concrete and a small share to the anchors via bending of the anchor channel. In addition for reasons of equilibrium the anchors are stressed by tension forces. In the approach presented above it is assumed that shear forces are transferred by bending of the channel to the anchors and by the anchors into the concrete. This simplified approach has been chosen to allow for simple interaction between tension and shear forces acting on the channel.

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5.3 Tension forces in a supplementary reinforcement

5.3.3 Tension loads

The design forces NED, re in the supplementary reinforcement should be calculated using the design load on the anchor.

5.3.4 Shear loads

The design tension force reEd ,N in the supplementary reinforcement caused by the design shear force VEd acting on a fixture is given by Equation (4).

1)( sEdreEd, +=

ze

VN (4)

with (see Figure 2):

es distance between reinforcement and shear force acting on the anchor channel

z internal lever arm of the concrete member

≈ 0,85 h'

≈ 0,85·(h - hch - 0,5ds)

≤1

ef22

min'ch

h

Figure 2 — Surface reinforcement to take up shear forces — detailing of reinforcement

If the supplementary reinforcement is not arranged in the direction of the shear force then this must be taken into account in the calculation of the design tension force of the reinforcement.

In the case of different shear forces on the anchors of the anchor channel, Equation (4) should be solved for the shear load h

EdV of the most loaded anchor channel resulting in hreEd,N .

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6 Verification of ultimate limit state by elastic analysis

6.1 General

6.1.5 In addition to the failure modes given in CEN/TS 1992-4-1:2009, Figures 20 and 21, the failure modes given in Figure 3 might occur.

Key a) local failure of the channel lip b) failure due to flexure of the channel c) failure of the anchor

Figure 3 — Additional failure modes for anchor channels

6.2 Tension loads

6.2.1 Required verifications

The required verifications are given in Table 1.

6.2.1.1 For anchor channels without supplementary reinforcement the verifications of Table 1, lines 1 to 9 apply.

6.2.1.2 For anchor channels with supplementary reinforcement the verifications of Table 1, lines 1 to 6 and 8 to 11 apply.

6.2.2 Design of supplementary reinforcement

When the design relies on supplementary reinforcement, concrete cone failure according to Equation (7) needs not to be verified but the supplementary reinforcement should be designed to resist the total load. The reinforcement should be anchored adequately on both sides of the potential failure planes.

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Table 1 — Required verifications for channel bars under tension loading

Failure mode Channel Most unfavourable anchor or screw

1

Steel failure

anchor Msas,Rk,as,Rd,aEd γ/NNN =≤

b

2 connection between anchor and channel caMs,cs,Rk,cs,Rd,

aEd / γNNN =≤

b

3 local flexure of channel lip lMs,ls,Rk,ls,Rd,Ed γ/NNN =≤ b

4 special screw MssRk,sRd,Ed γ/NNN =≤ b

5 flexure of channel flexMs,flexs,Rk,

flexs,Rd,Ed

γ/M

MM =≤

6 Pull-out failure MppRk,pRd,aEd γ/NNN =≤ b

7 Concrete cone failure MccRk,cRd,aEd γ/NNN =≤ c

8 Splitting failure MspspRk,spRd,aEd γ/NNN =≤ c

9 Blow-out failurea MccbRk,cbRd,aEd γ/NNN =≤ c

10 Steel failure of supplementary reinforcement reMs,reRk,reRd,

areEd, γ/NNN =≤ b

11 Anchorage failure of supplementary reinforcement McaRk,aRd,

areEd, γ/NNN =≤ b

a not required for anchors with c > 0,5 hef b most loaded anchor or special screw

c the load on the anchor in conjunction with the edge distance and spacing should be considered in determining the most unfavourable anchor

The supplementary reinforcement to take up tension loads should comply with the following requirements (see also Figure 4):

a) In general, for all anchors of a channel the same diameter of the reinforcement should be provided. It should consist of ribbed reinforcing bars (fyk ≤ 500 N/mm2) with a diameter ds not larger than 16 mm and should be detailed in form of stirrups or loops with a mandrel diameter according to EN 1992-1-1.

b) The supplementary reinforcement should be placed as close to the anchors as practicable to minimise the effect of eccentricity associated with the angle of the failure cone. Preferably, the supplementary reinforcement should enclose the surface reinforcement. Only these reinforcement bars with a distance ≤ 0,75 hef, from the anchor should be assumed as effective.

c) The minimum anchorage length of supplementary reinforcement in the concrete failure cone is s4 dl =1min (anchorage with bends, hooks or loops) or sdl 10min 1 = (straight bars with or without

welded transverse bars).

d) The supplementary reinforcement should be anchored outside the assumed failure cone with an anchorage length lbd according to EN 1992-1-1.

e) A surface reinforcement should be provided as shown in Figure 4a) designed to resist the forces arising from the assumed strut and tie model, taking into account the splitting forces according to 6.2.6.

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For anchors channels located parallel to the edge of a concrete member or in a narrow concrete member, the plane of the supplementary reinforcement shall be located perpendicular to the longitudinal axis of the channel (see Figure 4).

Key 1 supplementary reinforcement 2 surface reinforcement

Figure 4 — Arrangement of supplementary reinforcement

6.2.3 Steel failure

The characteristic resistances as,Rk,N (failure of anchor), cs,Rk,N (failure of the connection between anchor and channel), ls,Rk,N (local failure by flexure of the channel lips), sRk,N (failure of the special screw) and

flexs,Rk,M (failure by flexure of the channel) are given in the relevant European Technical Specification.

6.2.4 Pullout failure

The characteristic resistance pRk,N for pullout failure of the anchor is given in the relevant European Technical Specification.

NOTE The characteristic resistance pRk,N is limited by the concrete pressure under the head of the anchor

according to Equation (5):

Nucr,cubeck,hpRk, 6 ψfAN ⋅⋅⋅= (5)

with

Ah load bearing area of the head of the anchor

= ( )22h4

ddπ − in case of a round head (6)

fck,cube characteristic cube strength of the concrete strength class but noting the limitations given in the relevant European Technical Specification.

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Nucr,ψ = 1,0 for anchor channels in cracked concrete

= 1,4 for anchor channels in non-cracked concrete

6.2.5 Concrete cone failure

6.2.5.1 Characteristic resistance

The characteristic resistance of one anchor of a channel bar in case of concrete cone failure may be calculated according to Equation (7).

NRk, c = 0cRk ,N ⋅ αs, N ⋅ αe, N ⋅ αc, N ⋅ ψre, N ⋅ ψucr, N (7)

The different factors in Equation (7) are given in the following sections.

6.2.5.2 Basic characteristic resistance of an anchor

The basic characteristic resistance of one anchor not influenced by adjacent anchors, edges or corners of the concrete member located in cracked concrete is obtained by:

[N]58 51efcubeck,ch

0cRk,

,hfα,N ⋅⋅⋅= (8)

with

αch factor taking into account the influence of the channel on the concrete cone failure load. It is given in the relevant European Technical Specification.

≤ 1

fck,cube [N/mm²], characteristic cube strength of the concrete strength class but noting the limitations given in the relevant European Technical Specification.

hef [mm]

6.2.5.3 Effect of neighbouring anchors

The influence of neighbouring anchors on the concrete cone resistance is taken into account by the factor αs, N according to Equation (9).

∑=

⋅

−+

=n

i

,

NN

ss

α

1 0

i51

Ncr,

i

Ns,

11

1 (9)

with (see Figure 5):

si distance between the anchor under consideration and the neighbouring anchors

≤ scr,N

scr, N = 2 ⋅ (2,8 – 1,3 ⋅ hef /180) ⋅ hef ≥ 3 ⋅ hef (10)

Ni tension force of an influencing anchor

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N0 tension force of the anchor under consideration

n number of anchors within a distance scr,N to both sides of the anchor under consideration

Key 1 anchor under consideration

Figure 5 — Example of an anchor channel with different anchor tension forces

6.2.5.4 Effect of edges of the concrete member

The influence of an edge of the concrete member on the characteristic resistance is taken into account by the factor αe, N according to Equation (11).

150

Ncr,

1Ne, ≤= ,)

cc

(α (11)

with

c1 edge distance of the anchor channel (see Figure 6a))

ccr,N characteristic edge distance

= 0,5scr,N = efefef 5,1)180/3,18,2( hhh ⋅≥⋅⋅−

(12)

With anchor channels located in a narrow concrete member with different edge distances c1,1 and c1,2 (see Figure 6b)) the minimum value of c1,1 and c1,2 should be inserted in Equation (11).

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Figure 6 — Channel bar at an edge or in a narrow member

6.2.5.5 Influence of a corner of the concrete member

The influence of a corner of the concrete member on the characteristic resistance is taken into account by the factor αc, N according to Equation (13).

150

Ncr,

2Nc, ≤

=

,

cc

α (13)

with

c2 corner distance of the anchor under consideration (see Figure 7).

If an anchor is influenced by two corners, then the factor αc, N has to be calculated for the values c2,1 and c2,2

and the product of the factors αc, N should be inserted in Equation (7).

6.2.5.6 Effect of shell spalling

The shell spalling factor Nre,ψ takes account of the effect of a dense reinforcement for embedment depths hef < 100 mm:

1200

0,5 efNre, ≤+=

hψ [-] (14)

with

hef [mm]

Irrespective of the embedment depth of the anchor channel, Nre,Ψ may be taken as 1,0 in the following cases:

a) Local to this anchor channel reinforcement (any diameter) is provided at a spacing ≥ 150 mm, or

b) Reinforcement with a diameter of 10 mm or less is provided at a spacing > 100 mm.

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Key a) Resistance of anchor 1 is calculated b) Resistance of anchor 2 is calculated c) Resistance of anchor 2 is calculated d) Resistance of anchor 1 is calculated

Figure 7 — Definition of the corner distance of an anchor channel in the corner of a concrete member

6.2.5.7 Effect of the anchor channel position

The factor Nucr,Ψ takes account of the position of the anchor channel in cracked or non-cracked concrete.

Nucr,Ψ = 1,0 for anchors in cracked concrete (15)

= 1,4 for anchors in non-cracked concrete

6.2.5.8 Effect of a narrow member

For the case of anchor channels with hef > 180 mm in an application with influence of neighbouring anchors and influence of an edge and 2 corners (Figure 7c)) located with edge distance less than Ncr,c from the anchor under consideration the calculation according to Equation (7) leads to conservative results. More precise results are obtained if the value hef is substituted by the larger value of:

mm180ormm180 efNcr,

max'efef

Ncr,

max'ef ≥⋅=≥⋅= h

ss

hhcc

h (16)

with

maxc maximum distance from centre of an anchor to the edge of the concrete member ≤ ccr,N. In the example given in Figure (7c)) maxc is the maximum value of c1, c2,1 and c2,2

maxs maximum centre to centre spacing of anchors ≤ scr,N

The value 'hef is inserted in Equation (8) as well as in Equations (10) and (12).

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6.2.6 Splitting failure

6.2.6.1 Splitting failure due to installation of the special screw

Splitting failure is avoided during installation of the special screw by complying with minimum values for edge distance cmin , spacing smin , member thickness hmin and requirements on reinforcement as given in the relevant European Technical Specification.

NOTE Minimum values for edge distance, spacing and member thickness are also observed for anchor channels to allow adequate placing and compaction of the concrete.

6.2.6.2 Splitting failure due to loading

6.2.6.2.1 No verification of splitting failure is required if this is stated in the relevant European Technical Specification or at least one of the following conditions is fulfilled:

a) The edge distance in all directions is c > 1,0 ccr,sp for anchor channels with one anchor and c > 1,2 ccr,sp for anchor channels with more than one anchor.

The characteristic values of edge distance and spacing in the case of splitting under load, ccr, sp and scr, sp are given as a function of the member thickness in the relevant European Technical Specification.

b) The characteristic resistance for concrete cone failure, concrete blow-out failure and pull-out failure is calculated for cracked concrete and reinforcement resists the splitting forces and limits the crack width to wk ≤ 0,3 mm.

6.2.6.2.2 If the conditions a) and b) of 6.2.6.2.1 are not fulfilled, then the characteristic resistance of one anchor of a channel bar should be calculated according to Equation (17).

[N]sph,Nucr,Nre,Nc,Ne,Ns,0RkspRk, ψψψαααNN ⋅⋅⋅⋅⋅⋅= (17)

with

),min( 0cRk,pRk,

0Rk NNN =

pRk,N according to 6.2.4

sph,Nucr,Nre,Nc,Ne,Ns,0

cRk, ψ,ψ,ψ,α,α,α,N according to 6.2.5. However the values ccr,N and scrN should be

replaced by ccr,sp and scr,sp in Equations (9) to (13). The values ccr,sp and scr,sp are valid for the member thickness hmin. The factor sph,ψ takes into account the influence of the actual member depth h on the splitting resistance. For anchor channels according to current experience Equation (18) is valid:

3/2

min

ef3/2

minsph,

2

≤

=

hh

hhψ (18)

For fastenings with several edge distances (e.g. fastening in a corner of the concrete member or in a narrow member), the smallest edge distance c shall be inserted in Equation (17).

If the edge distance is smaller than the value ccr,sp a longitudinal reinforcement should be provided along the edge of the member.

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6.2.7 Blow-out failure

Verification of blow-out failure is not required with anchors when the distance between the anchorage area and the side surface of the structural component exceeds c = 0,5 hef. If verification is required, the characteristic resistance of one anchor in case of blow-out is:

[N]Nucr,Nbh,Nbc,Nbg,Nbs,0

cbRk,cbRk, ψααψαNN ⋅⋅⋅⋅⋅= (19)

The different factors in Equation (19) are given in the following.

NOTE For anchor channels located perpendicular to the edge, which are loaded uniformly, verification is only required for the anchors closest to the edge.

6.2.7.1 Basic characteristic resistance of a single anchor

The basic characteristic resistance of a single anchor without influence of neighbouring anchors and corner or member thickness effects is given by Equation (20):

cubeck,h1o

cbRk, 8 fAcN ⋅⋅⋅= [N] (20)

with Ah [mm²], load bearing area of the anchor

)d(dπ 22h4

−⋅= in case of a round head of the anchor (21)

c1 [mm], edge distance

6.2.7.2 Effect of neighbouring anchors

The influence of neighbouring anchors on the blow-out resistance is taken into account by the factor αs, Nb, which may be calculated analogous to Equation (9), however with scr, Nb = 4 c1.

6.2.7.3 Effect of a corner of the concrete member

The influence of a corner of the concrete member on the characteristic resistance is taken into account by the factor αc, Nb according to Equation (22):

150

Nbcr,

2Nbc, ≤

=

,

cc

α (22)

with

c2 corner distance of the anchor, for which the resistance is calculated (see Figure 7)

ccr, Nb = scr, Nb/2

If an anchor is influenced by two corners ( )2 12 cc < — example see Figure 7c) — then the factor Nbc,α should be calculated for the values of c2,1 and c2,2 and the product of the factors should be inserted in Equation (22).

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6.2.7.4 Effect of the bearing area

The factor ψg, Nb takes account of the bearing areas of the anchors.

14

11

1Nbg, ≥⋅−+=

cs

)n(nψ , 11 4c≤s (23)

with n number of tensioned anchors in a row parallel to the edge

6.2.7.5 Effect of the thickness of the concrete member

The influence of a distance ≤ 2 c1 between the anchor head and the upper or lower surface of the concrete member is taken into account by the factor αh, Nb according to Equation (24).

14

24 1

1

1

efNbh, ≤

+≤

+=

cfc

cfh

a (24)

with

f distance between the anchor head and the lower surface of the concrete member (see Figure 8).

Figure 8 — Channel bar at the edge of a thin concrete member

6.2.7.6 Effect of the position of the anchor channel

The factor ψucr, N takes into account of the position of the anchor channel in cracked or non-cracked concrete.

ψucr, N = 1,0 for anchor channels in cracked concrete (25)

= 1,4 for anchor channels in non-cracked concrete (26)

6.2.8 Steel failure of the supplementary reinforcement

The characteristic resistance the supplementary reinforcement NRk,,re of one anchor is

yksreRk, fAnN ⋅⋅= (27)

with

As cross section of one leg of the supplementary reinforcement

fyk nominal yield strength of the supplementary reinforcement ≤ 500 N/mm²

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n number of legs of the supplementary reinforcement effective for one anchor

6.2.9 Anchorage failure of the supplementary reinforcement in the concrete cone

The design resistance NRd,a of the supplementary reinforcement of one anchor is given by

∑ ⋅⋅⋅=

n αfdπl

N bds1aRd, (28)

with l1 anchorage length of the supplementary reinforcement in the assumed failure cone (see Figure 4) ≥ lb,min = 4 ⋅ ds (anchorage with bends, hooks or loops) ≥ lb,min = 10 ⋅ ds (anchorage with straight bars with or without welded transverse bars)

lb,min minimum anchorage length

ds diameter of the reinforcement bar

fbd design bond strength according to EN 1992-1-1, taking into account the concrete cover of the supplementary reinforcement

α influencing factor, according to EN 1992-1-1 = 0,7 for hooked bars

n number of legs of the supplementary reinforcement effective for one anchor

6.3 Shear loads

6.3.1 Required verifications

The required verifications are given in Table 2.

6.3.1.1 For anchor channels without supplementary reinforcement the verifications of Table 2, lines 1 to 5 apply.

6.3.1.2 For anchor channels with supplementary reinforcement the verifications of Table 2, lines 1 to 4 and 6, 7 apply.

6.3.2 Design of reinforcement

When the design relies on supplementary reinforcement, concrete cone failure according to Equation (32) needs not to be verified but the supplementary reinforcement should be designed to resist the total load. The supplementary reinforcement may be in the form of a surface reinforcement (Figure 9).

The supplementary reinforcement should be anchored outside the assumed failure cone with an anchorage length lb,net according to EN 1992-1-1.

In general, for all anchors of the channel bar the same diameter of reinforcement should be provided. It should consist of ribbed bars with fyk ≤ 500 N/mm² and a diameter not larger than 16 mm. The mandrel diameter, db, should comply with EN1992-1-1.

If the shear force is taken up by a surface reinforcement according to Figure 9, the following additional requirements should be met:

a) Only bars with a distance ≤ 0,75 c1 from the anchor should be assumed as effective.

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b) The anchorage length l1in the concrete breakout body is at least:

min l1 = 10 ds, straight bars with or without welded transverse bars (see Figure 9)

= 4 ds bars with a hook, bend or loop

c) A reinforcement along the edge of the member should be provided and be designed for the forces according to an appropriate strut and tie model (see Figure 9). As a simplification an angle of the compression struts of 45°may be assumed.

Table 2 —Verifications for anchor channels loaded in shear

Failure mode Channel Most unfavourable anchor or screw

1

Steel failure

shear force without lever arm

special screw MssRk,sRd,Ed /γVVV =≤ a

2 local flexure of channel lip lMs,ls,Rk,ls,Rd,Ed γ/VVV =≤

a

3 shear force with lever arm

special screw MssRk,sRd,Ed γ/VVV =≤ a

4 Pry-out failure MccpRk,cpRd,a

Ed γ/VVV =≤ b

5 Concrete edge failure MccRk,cRd,a

Ed γ/VVV =≤ b

6 Steel failure of supplementary reinforcement

reMs,reRk,reRd,

hreEd, γ/NNN =≤

a

7 Anchorage failure of supplementary reinforcement

aRd,

hreEd, NN ≤ a

a most loaded anchor or screw b The load on the anchor in conjunction with the edge distance and spacing should be considered in determining the most unfavourable anchor

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Figure 9 — Surface reinforcement to take up shear forces — simplified strut and tie model

6.3.3 Steel failure

6.3.3.1 Shear force without lever arm

The characteristic resistance sRk,V (failure of special screw) and ls,Rk,V (failure due to local flexure of channel lips) are given in the relevant European Technical Specification.

6.3.3.2 Shear force with lever arm

The characteristic resistance of a special screw in case of steel failure, sRk,V may be obtained from Equation (29).

lMα

V sRk,MsRk,

⋅= [N] (29)

with

αM The value Mα depends on the degree of restraint of the anchor channel at the side of the fixture of the application in question and should be determined according to good engineering practice. No restraint ( 01M ,α = ) should be assumed if the fixture can rotate freely. Full restraint ( 02M ,α = ) may be assumed only if the fixture cannot rotate. If restraint of the special screw is assumed the channel and/or the fastened element must be able to take up the restraint moment.

l lever arm

sRk,M = )1 sRd,Edo

sRk, /NN(M −⋅ (30)

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NRd,s = MssRk, /γN

osRk,M characteristic bending resistance of the special screw,

given in the relevant European Technical Specification

6.3.4 Concrete pry-out failure

The characteristic resistance of the most unfavourable anchor for concrete pry-out failure should be calculated according to Equation (31):

cRk,5cpRk, NkV ⋅= (31)

with

k5 factor to be taken from the relevant European Technical Specification valid for applications without supplementary reinforcement; in case of supplementary shear reinforcement the factor k5 should be multiplied with 0,75

NRk, c according to 6.2.5, determined for the anchors loaded in shear

6.3.5 Concrete edge failure

6.3.5.1 General

For anchor channels with an edge distance in all directions c > 10 hef and c > 60 d (d = diameter of the special screw), a check of the characteristic concrete edge failure resistance may be omitted. The smaller value is decisive.

6.3.5.2 Characteristic resistance

The characteristic resistance of one anchor loaded perpendicular to the edge corresponds to:

[N]Vre,90Vh,Vc,Vs,0

cRk,cRk, ψααααVV ,V ⋅⋅⋅⋅⋅= ° (32)

The different factors of Equation (32) are given below.

6.3.5.3 Basic characteristic resistance

The basic characteristic resistance of an anchor channel with one anchor loaded perpendicular to the edge not influenced by neighbouring anchors, member thickness or corner effects is:

[N]511cubeck,p

0cRk,

,cfαV ⋅⋅= (33)

with

αp factor given in the relevant European Technical Specification.

fck,cube [N/mm2], characteristic cube strength of the concrete strength class but noting the limitations given in the relevant European Technical Specification.

NOTE As default value αp = 2,5 may be taken

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6.3.5.4 Influence of neighbouring anchors

The influence of neighbouring anchors on the concrete edge resistance is taken into account by the factor αs, V according to Equation (34)

∑=

⋅

−+

=n

i

,

VV

ss

α

1 0

i51

cr,V

i

s,V

11

1 (34)

with (see Figure 10):

si distance between the anchor under consideration and the neighbouring anchors

≤ scr,V

scr, V = 4 ⋅ c1 + 2 bch (35)

bch width of anchor channel

Vi shear force of an influencing anchor

V0 shear force of the anchor under consideration

n number of anchors within a distance scr,V to both sides of the anchor under consideration

Figure 10 — Example of an anchor channel with different anchor shear forces

6.3.5.5 Effect of a corner

The influence of a corner on the characteristic edge resistance is taken into account by the factor c,Vα .

15,0

cr,V

2c,V ≤

=

ccα (36)

with

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ccr, V = 0,5 scr, V = 2 c1 + bch (37)

If an anchor is influenced by two corners (example see Figure 11b)), then the factor αc, V according Equation (36) shall be calculated for each corner and the product shall be inserted in Equation (32).

Figure 11 — Example of an anchor channel with anchors influenced by one (a) or two (b) corners, anchor 2 is under consideration

6.3.5.6 Effect of the thickness of the structural component

The influence of a member thickness h < hcr, V is taken into account by the factor αh, V.

150

Vcr,Vh, ≤

=

,

hhα (38)

with

hcr, v = 2 c1 + 2 hch, see Figure 12 (39)

hch = height of channel bar

Figure 12 — Example of an anchor channel influenced by the member thickness

6.3.5.7 Effect of load parallel to the edge

The factor V,90°α takes into account the influence of shear loads acting parallel to the edge (see Figure 13).

5,2V,90 =°α (40)

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Figure 13 — Anchor channel loaded parallel to the edge

6.3.5.8 Effect of the anchor channel position

The factor re,Vψ takes account of the effect of the position of the anchor channel in cracked or non-cracked concrete or of the type of reinforcement at the edge.

re,Vψ = 1,0 anchor channel in cracked concrete without edge reinforcement or stirrups

re,Vψ = 1,2 anchor channel in cracked concrete with straight edge reinforcement (> Ø12 mm)

re,Vψ = 1,4 anchor channel in cracked concrete with edge reinforcement and stirrups with a spacing a < 100 mm and a ≤ 2 c1 anchor channel in non-cracked concrete (proof according to CEN/TS 1992-4-1:2009, clause 5)

In case of presence of edge reinforcement for applications in cracked concrete a factor Vre,ψ > 1 shall only be used, if the height of the channel is mm40≤chh .

6.3.5.9 Effect of a narrow thin member

For an anchor channel in a narrow, thin member (see Figure 14) with c2, max ≤ ccr, v (ccr, V according to Equation (6.9e)) and h < hcr, V (hcr, V according to Equation (39), the calculation according to Equation (32) leads to conservative results. More precise results are achieved if the edge distance c1 in Equation (32) is limited to '

1c (see Equation (41)):

−

−=

222max

maxch

ch22121 )/h(h

)/b);c(c(c ,,' (41)

with

max,2c largest of the two edge distances parallel to the direction of load

The value '1c is inserted in Equations (33), (35), (37) and (39).

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Figure 14 — Illustration of an anchor channel influenced by two corners and member thickness (in this example c2,2 is decisive for the determination of c'1)

6.3.6 Steel failure of supplementary reinforcement

The characteristic resistance the supplementary reinforcement NRk,,re of one anchor is:

yksreRk, fAnN ⋅⋅= (42)

with

As = cross section of one leg of the supplementary reinforcement

fyk = nominal yield strength of the supplementary reinforcement ≤ 500 N/mm²

n = number of legs of the supplementary reinforcement effective for one anchor

6.3.7 Anchorage failure of supplementary reinforcement in the concrete cone

The design resistance NRd,a of the supplementary reinforcement of one anchor is given by:

∑ ⋅⋅⋅=

n αfdπl

N bds1aRd, (43)

with

l1 anchorage length of the supplementary reinforcement in the assumed failure cone (see Figure 9) ≥ lb,min = 4 ⋅ ds (anchorage with bends, hooks or loops) ≥ lb,min = 10 ⋅ ds (anchorage with straight bars with or without welded transverse bars)

lb,min minimum anchorage length

ds diameter of the reinforcement bar

bdf design bond strength according to EN 1992-1-1, taking into account the concrete cover of the supplementary reinforcement

α influencing factor, according to EN 1992-1-1 0,7 for hooked bars

n number of legs of the supplementary reinforcement effective for one anchor

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6.4 Combined tension and shear loads

6.4.1 Anchor channels without supplementary reinforcement

6.4.1.1 Steel failure decisive for tension and shear load

For combined tension and shear loads the following equations shall be satisfied (see Figure 15):

12V

2N ≤+ ββ (44)

where: 1RdEdN ≤= /NNβ and 1RdEdV ≤= /VVβ

In Equation (44) the largest value of βN or β V for the different failure modes shall be taken.

6.4.1.2 Other modes of failure decisive

For combined tension and shear loads either of the following Equations (45) (see Figure 15) or Equation (46) shall be satisfied:

βN + βV ≤ 1,2 (45)

11,5V

1,5N ≤+ ββ (46)

where

βN = NEd/NRd ≤ 1 and βV = VEd/VRd ≤ 1

In Equations (45) and (46) the largest value of βN and βV for the different failure modes shall be taken.

6.4.2 Anchor channels with supplementary reinforcement

6.4.2.1 For anchor channels with supplementary reinforcement to take up tension and shear loads Section 6.4.1 applies.

6.4.2.2 For anchor channels at the edge with supplementary reinforcement to take up shear loads, Equation (6.14) shall be used.

βN + βV ≤ 1 (47)

with

1/ RdEdN ≤= NNβ and 1/ RdEdV ≤= VVβ

In Equation (47) the largest value of βN or βV for the different failure modes shall be taken.

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Key 1) according to equation (44) 2) according to equation (45) 3) according to equation (46) 4) according to equation (47)

Figure 15 — Interaction diagram for combined tension and shear loads

7 Fatigue

Fatigue loading of anchor channels is not covered by this CEN/TS.

8 Seismic

Seismic loading of anchor channels is not covered by this CEN/TS.

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