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JANUARY 2014SFRC CONSORTIUMDESIGN GUIDELINE FORSTRUCTURALAPPLICATIONS OF STEELFIBRE REINFORCEDCONCRETEPublished by:SFRC ConsortiumThomas Kasper, Bo Tvede-Jensen - COWI A/SHenrik Stang - Danish Technical UniversityPeter Mjoernell, Henrik Slot, Gerhard Vitt - BekaertLars Nyholm Thrane - Danish Technological InstituteLars Reimer – CRH Concrete A/SCopyright 2014 SFRC Consortium
SFRC DESIGN GUIDELINE3CONTENTSForeword7Part 1 - Supplements and modifications to DS EN 19921-1811.11.21.51.6GeneralScopeNormative referencesDefinitionsSymbols88991022.22.42.5Basis of designPrinciples of limit state designVerification by the partial factor methodDesign assisted by testing1313131433.53.6MaterialsSteel fibresSteel fibre reinforced concrete14141444.4Durability and cover to reinforcementMethods of verification202055.65.75.85.95.10Structural analysisPlastic analysisNon-linear analysisAnalysis of second order effects with axial loadLateral instability of slender beamsPrestressed members and structures202020222222
SFRC DESIGN GUIDELINE466.16.26.36.46.56.76.8Ultimate limit states (ULS)Bending with or without axial forceShearTorsionPunchingDesign with strut and tie modelsPartially loaded areasFatigue222223252526272777.37.4Serviceability limit states (SLS)Crack controlDeflection control27273288.28.10Detailing of reinforcement and prestressingtendons – GeneralSpacing of barsPrestressing tendons33333399.19.29.39.59.69.8Detailing of members and particular rulesGeneralBeamsSolid eight aggregate concrete structures37Annex E (Informative)38Annex K (Normative) – Detailed determination of thefactor 239Annex L (Normative) – Determination and verificationof fibre orientation factors40Part 2 - Supplements and modifications to DS EN 206-1421Scope422Normative references4233.2Definitions, symbols and abbreviationsSymbols and abbreviations4242
SFRC DESIGN GUIDELINE544.3ClassificationHardened concrete434355.4Requirements for concrete and methods ofverificationRequirements for fresh concrete434366.2Specification of concreteSpecification for designed concrete434388.2Conformity control and conformity criteriaConformity control for designed concrete434399.29.59.9Production controlProduction control systemsConcrete composition and initial testingProduction control procedures44444445Annex A (normative) – Initial test47Annex H (informative) – Additional provisions for highstrength concrete48Annex L (normative) – Determination of the steel fibrecontent49Annex M (normative) – Initial test of steel fibrereinforced concrete53Part 3 - Supplements and modifications to DS EN14651561Scope5677.17.27.3Test specimensShape and size of test specimensManufacture and curing of test specimensNotching of test specimens5656565799.3Expression of resultsResidual flexural tensile strength5858
SFRC DESIGN GUIDELINE10Test report660Part 4 - Supplements and modifications to DS EN13670 / DS 2427621Scope6244.3Execution managementQuality management626288.18.3ConcretingSpecification of concreteDelivery, reception and site transport of freshconcretePlacing and compaction62628.4Part 5 - Supplements and modifications to BIPS C213Tegningsstandarder Del 3 - Betonkonstruktionerog Pæle626465
SFRC DESIGN GUIDELINE7ForewordThis guideline for the design of steel fibre reinforced concrete structures is to beapplied in conjunction with DS EN 1992-1-1 incl. Danish National Annex. Whilethis guideline covers the design aspects, execution aspects for casting of steel fibrereinforced concrete, in particular steel fibre reinforced self-compacting concrete,are given in the "Guideline for execution of SFRC".This guideline is based on the German guideline "DAfStb-Richtlinie Stahlfaserbeton" from March 2010, but contains a number of modifications as discussed inthe background document to this guideline.Steel fibres transfer tensile forces across cracks similar to rebar reinforcement. Thisproperty can be utilized both in Serviceability Limit State SLS and Ultimate LimitState ULS. However, it needs to be considered that the residual tensile strength dueto the effect of the steel fibres typically decreases with increasing deformation(crack opening). Figure F.1 illustrates the tensile behaviour of steel fibre reinforcedconcrete in comparison with plain concrete and conventionally reinforced concrete.FFSFRCPlane concreteFReinforced concreteFFDl wSFRCwPCDlDl n.wRCDlFigure F.1: Tensile load-displacement behaviour of plain, steel fibre reinforced and conventionally reinforced concreteThis guideline classifies steel fibre reinforced concrete based on performance classes. It distinguishes between Performance class L1 for small crack openings Performance class L2 for larger crack openingsThe designer is responsible for specifying the required performance classes, and incase of self-compacting steel fibre reinforced concrete the fibre orientation factors.The supplier of the steel fibre reinforced concrete1 is responsible for fulfilling therequired performance class and delivering a concrete with a uniform fibre distribution. The contractor is responsible for achieving a uniform fibre distribution andthe required fibre orientation in the structure.1The supplier of the steel fibre reinforced concrete is the party mixing the fibres into the concrete.Dl
SFRC DESIGN GUIDELINE8Part 1 - Supplements and modificationsto DS EN 1992-1-11 General1.1 Scope1.1.2 Scope of Part 1-1 of Eurocode 2Paragraph (1)P isreplaced(1)P This guideline applies in conjunction with DS EN 1992-1-1 to the design ofcivil engineering structures with steel fibre reinforced concrete and concrete withcombined (steel fibre and steel rebar) reinforcement. The guideline applies up toand including strength class C50/60. The guideline applies only when using steelfibres with mechanical anchorage.NOTE: Mechanically anchored fibres are usually undulated, hooked end or flat endfibres.For members loaded in bending or in tension designed according to this guideline,it must be verified that the ultimate load of the system is larger than the crack initiation load. This verification is only possible, if at least one of the following conditions is fulfilled: Redistribution of sectional forces within statically indeterminate structures Application of combined (steel fibre and steel rebar) reinforcement Axial compression forces due to external actionsStatically determinate structures that obtain their bending capacity only by steelfibres in a single cross section are not allowed. For these cases the cross sectionequilibrium must be ensured by additional steel rebar reinforcement.Paragraph (4)P issupplementedFurthermore, this guideline does not apply to: Lightweight aggregate concrete High strength concrete of compressive strength class C55/67 or higher Steel fibre reinforced sprayed concrete Steel fibre reinforced concrete without steel rebar reinforcement in the exposure classes XS2, XD2, XS3 and XD3, if the steel fibres are consideredin the structural verifications
SFRC DESIGN GUIDELINE9Note to last bullet: Steel fibres can be considered in the structural verifications inall exposure classes in case of combined steel fibre and steel rebar reinforcement.If this guideline is applied to prestressed or post-tensioned steel fibre reinforcedstructures, additional investigations shall be carried out to verify the design assumptions.New paragraph(G.5) is added(G.5) In principle, the application of this guideline for design of non-load bearingmembers is possible. The application of the guideline for that purpose should beagreed upon for the individual case.1.2 Normative references1.2.2 Other reference standardsThe following reference standards areaddedDS EN 14889-1:Fibres for concrete - Part 1: Steel fibres - Definitions,specifications and conformityDS EN 14651:Test method for metallic fibre concrete - Measuring theflexural tensile strength (limit of proportionality (LOP),residual)1.5 Definitions1.5.2 Additional terms and definitions used in this StandardThe following termsare added1.5.2.5 Steel fibre reinforced concrete. Steel fibre reinforced concrete is a concrete according to DS EN 206-1, to which steel fibres are added to achieve certainproperties. This guideline takes account of the effect of the fibres.1.5.2.6 Residual tensile strength. Notional residual tensile strength of the steelfibre reinforced concrete in the tension zone. It relates the true tensile forces in thesteel fibres to the area of the tension zone and to the direction perpendicular to thecrack plane.1.5.2.7 Residual flexural tensile strength. It represents the post-crack flexuraltensile strength of the cross section for bending.1.5.2.8 Performance class. Classification of steel fibre reinforced concretebased on the characteristic values of post-crack flexural tensile strength for crackmouth opening displacements 0.5 and 3.5 mm in DS EN 14651 beamtests according to Part 3 of this guideline.
SFRC DESIGN GUIDELINE101.6 SymbolsThe following symbols are addedLatin upper case lettersTension zone area of cracked cross sections or plastic hinges associated with the respective equilibrium state,Minimum rebar reinforcement area of steel fibre reinforced concreteCrack mouth opening displacementCrack mouth opening displacement in the tests according to Part 3for evaluation of the residual tensile strength in performance class1Crack mouth opening displacement in the tests according to Part 3for evaluation of the residual tensile strength in performance class2Flexural tensile force resulting from the residual tensile strength ofthe steel fibre reinforced concretePerformance class12Performance class 1Performance class 2,,,Design value of the shear resistance of steel fibre reinforced concrete without shear reinforcementDesign value of the shear resistance due to the contribution of thesteel fibresDesign value of the shear resistance of steel fibre reinforced concrete with shear reinforcement including the contribution of thesteel fibresLatin lower case lettersBasic value of the axial residual tensile strength of steel fibre reinforced concrete,Basic value of the axial residual tensile strength of steel fibre reinforced concrete in performance class 1 when applying the complete stress-strain curve according to Figure G.1 or Figure G.2,Basic value of the axial residual tensile strength of steel fibre reinforced concrete in performance class 2 when applying the com-
SFRC DESIGN GUIDELINE11plete stress-strain curve according to Figure G.1 or Figure G.2,Basic value of the axial residual tensile strength of steel fibre reinforced concrete when applying the rectangular stress block,Basic value of the axial residual tensile strength of steel fibre reinforced concrete in SLSCharacteristic value of the flexural residual tensile strength of steelfibre reinforced concrete,Design value of the axial residual tensile strength of steel fibre reinforced concrete in performance class 1 when applying the complete stress-strain curve according to Figure G.1 or Figure G.2,Design value of the axial residual tensile strength of steel fibre reinforced concrete in performance class 2 when applying the complete stress-strain curve according to Figure G.1 or Figure G.2,Design value of the axial residual tensile strength of steel fibre reinforced concrete when applying the rectangular stress block,Design value of the axial residual tensile strength of steel fibre reinforced concrete in SLS,Calculation value of the axial residual tensile strength of steel fibrereinforced concrete,Calculation value of the axial residual tensile strength of steel fibrereinforced concrete in performance class 1 when applying thecomplete stress-strain curve according to Figure G.1 or Figure G.2,Calculation value of the axial residual tensile strength of steel fibrereinforced concrete in performance class 2 when applying thecomplete stress-strain curve according to Figure G.1 or Figure G.2,Calculation value of the axial residual tensile strength of steel fibrereinforced concrete when applying the rectangular stress block,Calculation value of the axial residual tensile strength of steel fibrereinforced concrete in SLSLength, over which a crack in the steel fibre reinforced concrete isconsidered as smeared in order to calculate the tensile strain ofsteel fibre reinforced concrete!,Design value of the shear resistance along the control perimeterdue to the contribution of the steel fibres!, ,"Design value of the shear resistance along the control perimeter ofa plate without punching shear rebar reinforcement, taking into
SFRC DESIGN GUIDELINE12account the contribution of the steel fibres#Internal lever arm of the flexural tension force resulting from theresidual tensile strength of the steel fibre reinforced concreteGreek lower case letters Ratio of the calculation value of the residual tensile strength ofsteel fibre reinforced concrete to the mean value of the concretetensile strength; reduction factor to take account of long-term effects on the residual tensile strength Ratio of the calculation value of the residual tensile strength to themean value of the concrete tensile strength Reduction factor tailored to the design concept to take account oflong-term effects on the residual tensile strength of steel fibre reinforced concreteFactor for determining the basic values of the axial residual tensilestrengthFactor for the determination of the basic value of the axial residualtensile strength of steel fibre reinforced concrete in performanceclass 1 when applying the complete stress-strain curve according toFigure G.1 or Figure G.2Factor for the determination of the basic value of the axial residualtensile strength of steel fibre reinforced concrete in performanceclass 2 when applying the complete stress-strain curve according toFigure G.1 or Figure G.2Factor for the determination of the basic value of the axial residualtensile strength of steel fibre reinforced concrete when applying therectangular stress blockFactor for the determination of the basic value of the axial residualtensile strength of steel fibre reinforced concrete in SLSγPartial factor for the residual tensile strength of steel fibre reinforced concreteεCalculation value of compressive strain of steel fibre reinforcedconcreteεεεCalculation value of tensile strain of steel fibre reinforced concrete,Calculation value of ultimate tensile strain of steel fibre reinforcedconcreteMean strain of the rebar reinforcement taking into account the con-
SFRC DESIGN GUIDELINE13tribution of the steel fibres'Factor to take account of the size of the member (size effect); factor to take account of the fibre orientation'(Factor to take into account the influence of the member size on thecoefficient of variation')Factor to take into account the fibre orientation when determiningthe calculation values of the axial residual tensile strength from thebasic values of the axial residual tensile strength*Tensile stress of steel fibre reinforced concreteModified rebar diameter of rebar reinforcement for the crack widthverification with consideration of the steel fibre contributionφ2 Basis of design2.2 Principles of limit state designNew paragraph(G.2) is added(G.2) The ultimate limit state is reached, if in the critical sections of the structure the critical strain of the steel fibre reinforced concrete or the critical strain of the steel rebar reinforcement or the critical strain of the concrete is reachedor if the critical state of indifferent equilibrium of the structural system is reached.A stabilisation of the system by considering the tensile strength of the concrete orthe tensile strength of steel fibre reinforced concrete is not allowed, whereas theresidual tensile strength can be considered.2.4 Verification by the partial factor method2.4.2 Design values2.4.2.4 Partial factors for materials
SFRC DESIGN GUIDELINEAn additional column is added in Table 2.1NTable 2.1N:14Partial factors for materials for ultimate limit statesDesign situationsγ for steel fibre reinforced concrete with and withoutsteel rebar reinforcementPersistent & Transient1.25Accidental1.252.5 Design assisted by testingParagraph (1) issupplementedDesign assisted by testing needs to fulfil the same principles, safety concepts andstructural integrity as described in DS EN 1992-1-1 and this guideline.For steel fibre reinforced concrete, special investigations are required if the contribution of fibres should be taken into account in the design of dynamically loadedstructures.Additional investigations are required to verify the design assumptions, if thisguideline is applied to prestressed or post-tensioned steel fibre reinforced structures.3 MaterialsNew Section 3.5 isadded3.5 Steel fibresNew Section 3.6 isadded3.6 Steel fibre reinforced concrete(1)P DS EN 1992-2 and DS EN 14889-1 apply. The conformity of the steel fibresis required to be documented by a CE certificate of conformity (system 1).3.6.1 General(1)P Steel fibres are oriented in different directions and their ability to transfer tensile forces depends on their orientation relative to the crack plane. The informationabout the relative amount of fibres in the different directions is referred to as thefibre orientation. If the relative amount of fibres in different directions varies, thenthe ability of fibres to transfer tensile forces also varies depending on the direction.This will result in a variation of the residual tensile strength in different directions.(2)P The effect of the fibre orientation on the residual tensile strength of steel fibrereinforced concrete is accounted for as follows (Annex L):
SFRC DESIGN GUIDELINE15The performance classes define the residual tensile strength for the reference fibreorientation as observed in 3-point beam bending tests with steel fibre reinforcedslump concrete according to Part 3.For steel fibre reinforced self-compacting concrete, the test beams are cast with areference casting method as defined in Part 3, Section 7.2, which results in a reproducible fibre orientation. The strength values from the tests are converted tostrength values and performance classes for the reference fibre orientation.The fibre orientations in the actual structural applications are considered by a fibreorientation factor ') .(2)P The performance classes of steel fibre reinforced concrete are identified withthe prefix L. The performance classes shall be specified in accordance with thecrack openings associated with the limit state and failure mode. Table G.1 containsrecommended performance class definitions. The first value specifies the perfor 0.5 mm andmance class L1 for a crack mouth opening displacementthe second value the performance class L2 for 3.5 mm.Table G.1:values and performance classes for steel fibre reinforced concretePerformance classVerification inL1SLS 0.5 mmL2ULS 3.5 mmvalues determined according to Part3 of this guideline3.6.2 PropertiesSteel fibre reinforced concrete has a residual tensile strength (cf. Figure G.1 andFigure G.2). This notional residual tensile strength is related to the cross section ofthe concrete. It must not be used for determining the steel stresses in the fibres.3.6.3 Strength(1)P The performance class values correspond to the characteristic values of theresidual flexural tensile strength for the reference fibre orientation and the respective crack mouth openings. These characteristic values are to be verified accordingto Part 3 of this guideline.Performance classes should be specified according to the following examples:C30/37 L1.2/0.9 - XC1 for a steel fibre reinforced slump concreteSCC30/37 L1.2/0.9 - XC1 for a steel fibre reinforced self-compacting concretewhere:
SFRC DESIGN GUIDELINE16C30/37SCC30/37Compressive strength of the concrete according to DS EN 206-1L1.2/0.9Steel fibre reinforced concrete of performance class L1-1.2 forand performance class L2-0.9 forcf. Part 3 of thisguidelineXC1Exposure class of the concreteNOTE: The performance class L1 is typically larger than or equal to performanceclass L2.For self-compacting concrete, fibre orientation factors ') and the associated directions shall be specified for each structural member / casting section, cf. Part 5 ofthis guideline.(2)P The basic values of the axial residual tensile strength in Table G.2 are obtained from the characteristic values of the flexural residual tensile strength as ,,,, ,,,, (G.3.31)(G.3.32)(G.3.33)(G.3.34)where:,Basic value of the axial residual tensile strength according to TableG.2 column 2,Basic value of the axial residual tensile strength according to TableG.2 column 4,Basic value of the axial residual tensile strength according to TableG.2 column 5,Basic value of the axial residual tensile strength according to TableG.2 column 6Value according to paragraph (3)Value according to paragraph (3) 0.37 0.40For the rectangular stress blockFor SLS
SFRC DESIGN GUIDELINE17(3) If the ratio of the performance class values L2/L1 is larger than 0.7, 0.40 and 0.25 may be used. Otherwise, the rectangular stress blockmust be used for the ULS verification. Reference is made to Annex K for moredetailed determination of.(4)P If the ratio of the performance class values L2/L1 is larger than 1.0, the rectangular stress block must not be used.(5)P The calculation values of the axial residual tensile strength are determinedbased on the basic values of the axial residual tensile strength as: ') '( ,,,, ') '( ') '( ') '( or to take into account the influence of the member size on the 0.5 1.70coefficient of variation 1.0 Fibre orientation factor. For slump concrete, ') 0.5 shall be usedin general, however, for plane structures cast in horizontal position(width 5 height) ') 1.0 may be used for flexural and tensileloading. For self-compacting concrete, reference is made to AnnexL for determination and verification of fibre orientation factors.Recommended values for fibre orientation factors in specific applications and design aspects are contained in Section 9 of this guideline.Cross sectional area of the cracked areas or plastic hinges in m2associated with the respective equilibrium stateNOTE: For members subject to pure bending without axial forcesumed as 0.9 .may be as-
SFRC DESIGN GUIDELINE18Table G.2: Performance classes L1 and L2 for steel fibre reinforced concrete with corresponding basic values of the axial residual tensile strength in MPa,L11)2),L2,2)0 0.160–––0.4 1)0.160.4 0.751.111.11Only for plane members (b 5h)Applies if L2/L1 1.0. If L2/L1 1.0, see paragraph (4)PNOTE: In case,, ,or ,, onlyare allowed to be used in the design., , , 3.6.4 Stress-strain relation for non-linear structural analysisand for deformation analysis(1) The stresses and strains model notionally the behaviour of steel fibre reinforcedconcrete. Depending on the ratio L2/L1 (cf. Annex K), either the trilinear stressstrain relation or the rectangular stress block shall be used. Symbols in Figure G.1and Figure G.2 are as follows:*Tensile stress of steel fibre reinforced concrete,Design value of the axial residual tensile strength of steel fibre reinforced concrete in performance class 1 when applying the entirestress-strain curve given in Figure G.1 and Figure G.2,Design value of the axial residual tensile strength of steel fibre reinforced concrete in performance class 2 when applying the entirestress-strain curve given in Figure G.1 and Figure G.2,Design value of the axial residual tensile strength when applying
SFRC DESIGN GUIDELINE19the rectangular stress block,εDesign value of the axial residual tensile strength in SLSStrain of steel fibre reinforced concreteγPartial factor according to Table 2.1N 0.85; reduction factor tailored to the design concept to take account of long-term effects on the residual tensile strength of steelfibre reinforced concrete(2)P For non-linear analysis, the linear progression of the stress-strain curve up toshould be considered. This also holds for detailed deformation analysis. Forthe determination of cross sectional forces and for approximate deformation analysis the linear progression up tomay be disregarded.e fct ( )253.5 0.3 f ctm Ecmf1.04 f ctR,L2f1.04 f ctR,uf1.04 f ctR,L1f ctmsctf (MPa)Figure G.1: Stress-strain relation of steel fibre reinforced concrete in the tension zone forthe determination of sectional forces by non-linear structural analysis and for deformationanalysis3.6.5 Stress-strain relation for cross section verificationDepending on the ratio L2/L1 (cf. Annex K), either the complete stress-strain relation (solid lines) or the rectangular stress block (dashed lines) in Figure G.2 shallbe used in the tension zone for the cross section design in ULS.e ct ( )f253.50.1ff ctd,L2 a c . f ctR,L2 g fctff ctd,u a c . f ctR,uffffg fctf ctd,L1 a fc . f ctR,L1 g fctffsct (MPa)fFigure G.2: Stress-strain relation of steel fibre reinforced concrete in the tension zone forcross sectional design in ULS except for non-linear structural analysis
SFRC DESIGN GUIDELINE204 Durability and cover to reinforcement4.4 Methods of verification4.4.1 Concrete cover4.4.1.2 Minimum cover, cminParagraph (1)P issupplementedFor the verification of fire resistance of structural members with combined reinforcement, DS EN 1992-1-2 incl. Danish National Annex applies.Paragraph (5) issupplementedThe minimum cover cmin,dur only applies to rebar reinforcement and not to steel fibres. Fibres close to the surface may corrode, which may cause rust stains. However, the durability is not affected by corrosion of fibres.5 Structural analysis5.6 Plastic analysis5.6.1 GeneralNew paragraph(G.5)P is added(G.5)P Methods based on plastic analysis are generally applicable for steel fibrereinforced concrete structures, if the major part of the tensile and bending resistance is provided by rebar reinforcement. Otherwise, the application of plasticanalysis is limited to ground supported slabs, anchored underwater concrete slabs,pile supported floor slabs, shell structures and monolithically cast, prefabricatedcontaining structures.5.7 Non-linear analysisParagraph (1) issupplementedNon-linear methods of analysis are generally applicable for steel fibre reinforcedconcrete structures, if the major part of the tensile and bending resistance is provided by rebar reinforcement. Otherwise, the application of non-linear analysis is limited to ground supported slabs, anchored underwater concrete slabs, pile supportedfloor slabs, shell structures and monolithically cast, prefabricated containing structures.Paragraph (G.6) to(G.11) are added(G.6) A suitable non-linear method of analysis including cross section verificationis described in paragraph (G.6) to (G.11).For steel fibre reinforced concrete structures, the design resistance is defined as5 56; 1.04 ,;8;9/;(G.5.12.1)
SFRC DESIGN GUIDELINE21where:1.04 ,8;,8the mean value of the residual tensile strength of steel fibre reinforcedconcrete in performance class 1 and 2 according to Section 3.6.3,the respective mean value of the strength of concrete and rebar reinforcement steel: 0.85 1.1 1.05 1.08 8 (G.5.12.2)(G.5.12.3)88for Class A(G.5.12.4)for Class B(G.5.12.5)the partial factor for the resistance of the structural system(G.7)P For deformation analysis and determination of internal forces of steel fibrereinforced concrete, the stress-strain relation in Figure G.2 shall be used for thetension zone. For the compression zone, Section 3.1.5 applies without modification. For rebar reinforcement steel, Section 3.2 applies.(G.8) For steel fibre reinforced concrete, ; 1.4 shall be applied. For combinedreinforcement, generally ; 1.35 may be applied, or1.3 1.3 and0.1 1.4(G.5.12.2)are explained in Figure G.3.FcdxCompressionzfh dzsTensionFfdFsdbFigure G.3:Contribution of steel fibres Ffd and contribution of rebar reinforcement Fsdto the bearing capacity(G.9)P The design resistance must not be smaller than the design value of the effectof actions.(G.10)P The ultimate limit state is reached, if the ultimate strain of the concrete,the ultimate strain of the rebar reinforcement steel or the ultimate strain of steelfibre reinforced concrete ε 25 ‰ according to Section 3.6.4 is reached in anycross section of the structural system. The ultimate limit state is further reached, if
SFRC DESIGN GUIDELINE22a state of indifferent equilibrium is reached in (part of) the structural system. Theultimate strain of the rebar reinforcement steel shall be taken as ? 0.025 or( )? ?@ 0.025 0.9? .(G.11) For steel fibre reinforced concrete, tension stiffening should be consideredaccording to the standard rules for reinforced concrete. When calculating the stressin the rebar reinforcement, the effect of the steel fibres should be considered.5.8 Analysis of second order effects with axial load5.8.2 GeneralNew paragraph (7) isadded(G.7) For steel fibre reinforced members subject to buckling, the effect of the fibresmust not be considered in the design.5.9 Lateral instability of slender beamsNew paragraph (5) isadded(G.5) For the verification of lateral instability of slender steel fibre reinforcedbeams, the effect of the fibres must not be considered.5.10 Prestressed members and structuresIf the provisions in this section are applied to steel fibre reinforced concrete structures, additional investigations shall be carried out to verify the design assumptions.6 Ultimate limit states (ULS)6.1 Bending with or without axial forceParagraph (2)P issupplementedWhen determining the ultimate resistance of steel fibre reinforced concrete crosssections, the following additional assumptions are made: The compressive and tensile stresses
This guideline for the design of steel fibre reinforced concrete structures is to be applied in conjunction with DS EN 1992-1-1 incl. Danish National Annex. While this guideline covers the design aspects, execution aspects for casting of steel fibre reinforced concrete, in particular steel fibre reinforced self-compacting concrete,
