EN1995-1-1: Section 8 - Connections - Eurocodes

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 1TIMBER CONNECTIONSbyDr. Ad LeijtenTU-EindhovenThe NetherlandsFormer PT-member

EUROCODESBackground and ApplicationsBrussels, 18-20 February 2008 – Dissemination of information workshop 2We can not escape connectionsTHE WEAKEST LINK

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 3What kind of connections do we use?

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 4Carpenter connections (not in Eurocode 5)National regulations apply

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 5Carpenter connections compression forces

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 6Glued connections (not in Eurocode 5)Structural Finger joints Glued in steel rodsNational regulations apply

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 7What do we find in Eurocode 5Section 8: Connections with metal fastenersMechanical connections withDowel type fasteners- Nails, staples,- punched metal plates,- screws,- dowels and boltsConnectors- Shear plates- Split-rings

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 8Nails < 8 mm (EN14592)definition profiled nailsBolts > 8 mmScrewsDowels > 6 mm

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 9Punched metal plate fastenersSplit-ring connectors64- 104 mm diameterBolts M12 to M20

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 10Steel – to – timber

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 11Eurocode 5 allows:Design by testing:EN 1075 – tests punched metal plates connectionsEN 1380 – tests nails,screws,dowels,bolted conn.EN 1381 - tests on stapled connections.EN 26891 – Specimen density selection.EN 28970 – Test procedure for connection tests.Design by calculation- Model provided in EN1995-1-1

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 12Design by calculation - covers

a 3,ta 3,cEUROCODESBackground and ApplicationsBrussels, 18-20 February 2008 – Dissemination of information workshop 13Fastener spacing requirementsKey:(1) Loaded end(2) Unloaded end(3) Loaded edge(4) Unloaded edgea)a 2a 221a 2a 2a 1a 1a 1a 1b)αa 4,tα α αa 4,c-90° ≤ α ≤ 90° 90° ≤ α ≤ 270° 0° ≤ α ≤ 180° 180° ≤ α ≤ 360°(1) (2) (3) (4)

EUROCODESBackground and ApplicationsBrussels, 18-20 February 2008 – Dissemination of information workshop 14Fastener spacing requirements (bolts)Spacing and end/edgedistances(see Figure 8.7)a 1(parallel to grain)a 2(perpendicular to grain)Angle0 ° 360 °0 ° 360 °Minimum spacing ordistance(4 + cos ) d4 da 3,t(loaded end)a 3,c(unloaded end)a 4,t(loaded edge)a 4,c(unloaded edge)-90 ° 90 °90 ° < 150 °150 ° < 210 °210 ° 270 °0 ° 180 °180 ° 360 °max (7 d; 80 mm)max([1 + 6 sin ) d; 4d)4 dmax([1 + 6 sin ) d; 4d)max([2 + 2 sin ) d; 3d)3 d

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 15Spacing requirements determine timber dimensionsDecrease memberwidth ?a 1a 2

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 16Spacing requirements determine timber dimensionsk a1 a 1Only for connectorsa 2Split-rings andshear platesk a1a 1k a2 a 2k a2a 22 20 ≤ ka1≤ 1( ka1) + ( ka 2) ≥1 with 0 ≤ ka 2 ≤ 1

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 17Laterally loadedaxially loadedThe strength capacity model forlaterally loaded dowel-type-fasteners(based on Johansen (1949)Background:-Structural Education Timber Program (STEP 1)(1994)-Timber Engineering; Thelandersson & Larsen (2003) ISBN 0-470-84469-8

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 18single shearfastenersmultiple shear

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 19Double shearEmbedmentstresses

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 20Starting point for strength model - Embedment strengthEmbedment = f embf emb displacementembedmentIdealisedfemb= fv

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 21Determination of embedment strength –EN 383Eurocode 5 Design clause embedment strengthNails (not pre-drilled)Nails pre-drilledBolts/dowelsfh,kh,k-0,320,082 ρkN/mmf = d= 0,082 (1- 0,01 d ) ρ N/mmk2

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 22ParallelPerpendicularTaken from Sawata and Yasumura (2002).Background: Whale L. and Smith, I. The derivation of design clauses for nailed and bolted joint in Eurocode5, In Proceedings of paper CIB-W18 paper 19-7-6/ Florenze 1986Yasumura, M. and Sawata, K., Determination of embedment strength of wood for dowel-type-fasteners. In:Journal of Wood Science, nr. 48, 2002, Japan Wood Research Society, Inst. Of Wood Techn, Akita, Japan

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 23Embedment test - parallel to grainDowels Parallel All wood species120,0Embedment100,080,060,040,020,00,0200 400 600 800 1000 1200Density5mm data7mm data8mm data12mm data16mm data20mm data30mm dataBackground: Leijten, A.J.M. & Köhler, J.& A Jorissen, Review of Probability Data for Timber Connectionswith Dowel-Type Fasteners; In Proceedings of CIB-W18, paper 37-7-12, Edinburgh, UK, September 2004

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 24Re-evaluation parallel to grain embedment resultsfor future consideration in EC5?Nails (pre-drilled)ConiferousBolts and dowelsConiferousDecideousffffffh;0h;90h;0h;90h;0h;90= 0,0104ρ= 0,046ρ= 0,097ρ= ?= 0,087ρ= 0,106ρd1,35 −0,27d1,48 −0,42d1,07 −0,25d1,09 −0,25d1,13 −0,46

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 25Embedment - perpendicular to grain

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 26Embedment – at angle to grainBolts/dowel:fh,0,k= 0,082 (1- 0,01 d ) ρkfh,,k=fh,0,k2 2k 90 sin α + cos αk901,35 + 0,015 d for softwoods= 0,90+ 0,015 d for hardwoods

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 27Coniferous: Embedment test - perpendicular to grainEmbedding strength, based on average values embedding tests(European Whitewood (EW), European Redwood (ER), Canadian Spruce Pine Fir (CS))fh;90 (Embedding strength) [N/mm 2 ]40353025201510NailsBoltsNails ERNails EWNails CSBolts ERBolts EWBolts CSEurocode 5Power (All)Power (Eurocode 5)Eurocode 5500 5 10 15 20Nail or Bolt diameter [mm]Needs adjustment in future EC5

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 28Embedment rulesNails in:PlywoodHardboardParticleboard & OSBfh,k= 0,11ρ dh,k= 30kf d t−0,3 0,6f d th,k= 65−0,3−0,7 0,1Taken from DIN 1052

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 29Mode I Mode II Mode IIISome failure modes ofsingle shear fastenersSome failure modes ofdouble shear fasteners

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 30Equations for every failure modeFasteners in single shearFv,Rk fh,1,kt1d(a) fh,2,kt2d(b)2 1 1 (c)= min 1, 05 2 β (1 + β ) + − β +(d)2 2fh,1,kt1d 2 t2 t2 3 t2 t2β + β + + + β − β + 1 + β t1 t1 t1 t1fh,1,kt1d 4 β (2 + β)M y,RkFax,Rk22 + βfh,1,k d t14fh,1,kt2d 4 β (1 + 2 β)My,RkFax,Rk1, 05 21 + 22βfh,1,k d t24 2 β (1 + β ) + − β +(e) 2βFax,Rk1,15 2 My,Rkfh,1,kd+(f) 1 + β4

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 31Equations for every failure modeFasteners in double shearF fh,1,kt1d(g)0,5 fh,2,kt2d(h) f t d 4 β (2 + β ) M F= + + − + + 2βFax,Rk1,15 2 My,Rkfh,1,kd+(k) 1+β4h,1,k 1y,Rkax,Rkv,Rkmin 1,05 2 β (1 β ) β(j)22 βfh,1,kd t14

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 32Some failure modes ofsingle shear fastenerssteel to woodconnectionsthick steel plate t > d = fastener diameterthin steel plate t < 0,5d

EUROCODESBackground and ApplicationsBrussels, 18-20 February 2008 – Dissemination of information workshop 33Test results still higher than Johansen equationsCord effect:Only valid forMode II and IIIRequires knowledge about withdrawalTheory for nails 15% extraBackground: Kuipers, J. Van der Put, T.A.C.M., Betrachtungen zum Bruchmechanismus von Nagel verbindungen,In: Ingenieuholzbau in Forschung und Praxis, J. Ehlebeck and G. Steck, editors, Bruderverlag Karlsruhe 1982

EUROCODESBackground and ApplicationsBrussels, 18-20 February 2008 – Dissemination of information workshop 34Test results still higher than Johansen equationsCord effect:Fax/4 = withdrawal capacity/4 = estimated effect% are estimatesMaximumNails 15%Grooved nails 50%Screws 100%Bolts 25%Dowels 0%

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 35Fasteners in double shearF fh,1,kt1d(g)0,5 fh,2,kt2d(h) f t d 4 β (2 + β ) M F= + + − + + 2βFax,Rk1,15 2 My,Rkfh,1,kd+(k) 1+β4h,1,k 1y,Rkax,Rkv,Rkmin 1,05 2 β (1 β ) β(j)22 βfh,1,kd t14Test results still higher than Johansen equations

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 36Mode IIItheoryDesign valueFFd2⋅δ1+ δ=s h, 1kmod0,9= Fk⋅ = Fk⋅ = 0, 69⋅Fy 1,3m2⋅MschroefMs = yield bending moment steel fastener⋅dPartial material factor of timber γmapplied to Ms !!Better seperate:⋅⋅fk

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 37Mode IIITaking both γm - seperatelyFFFFdddd4δ= ⋅1+δ4δ= ⋅1+δkMyMe,km,se,k1,14δ= 0,79 ⋅ ⋅1+δ= 0,79 ⋅ F⋅d⋅dMschroefschroefe,k⋅d⋅⋅ffh,1,kym,hh,1,k1,3schroef⋅⋅k⋅0,9fmodh,1,kfactor=0,79 ⋅ F0,69 ⋅ Fkk= 1,15For Mode II factor is 1,05

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 38Fasteners in double shearF fh,1,kt1d(g)0,5 fh,2,kt2d(h) f t d 4 β (2 + β ) M F= + + − + + 2βFax,Rk1,15 2 My,Rkfh,1,kd+(k) 1+β4h,1,k 1y,Rkax,Rkv,Rkmin 1,05 2 β (1 β ) β(j)22 βfh,1,kd t14Eurocode 5 equations

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 39Yield moment of dowel type fastenersLarge diameter bolts and dowelsSmall rotation at failure No full plastic yieldingMy,Rk=0,3fu,kd2,6RRotationangle20.018.016.014.012.010.08.06.04.02.0Background: Jorissen, A.J.M. Blass, H.J., the fasteneryield strength in bending, In: Proceedings of CIB-W18paper 31-7-6, 19980.08 10 12 14 16 18 20 22 24 26 28 30diameterd

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 40Failure of multiple of fasteners in a rowSplittingShearTensile

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 41Failure of multiple of fasteners in a rowCaused by group effect Only for load component in grain directionStress ⊥13dCumulatievestress

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 42Failure of multiple of fasteners in one rowCaused by group effect effective numberNails:Empirical (Gehri)n = nBolts & dowels:Fracture mechanicsnefef=nk0,94efa013dSpacing aa 1≥ 14da 1= 10da 1= 7da 1= 4dNotpredrilledaFor intermediate spacings, linearinterpolation of k efis permittedBackground:Double shear timber connections with dowel type fasteners, A.J.M. Jorissen, ISBN 90-407-1783-4, DUP Delft,19981,00,850,7-k efPredrilled1,00,850,70,5

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 43Be careful with cheese connections

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 44Steelplate – in – timberChees connectionsSmall dowels

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 45Failure at fastener perimeter (Prof.Racher, Fr.)Block shear:Full penetrationPlug shearPartial penetrationTensile or shear failure, which happens first?Literature: Johnson, H, Stehn, L, A Linear Fracture Mecanics Evaluation of Plug Shear Failure,In Proc of 8thworld conf on Timber Engineering WCTE 2004, Finland

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 46Fbs,Rk 1,5 A= max 0,7 Anet,tnet,vft,o,kfv,kTensile failureShear fractureCorrelationparametersFasteners keepstraightNot correct inEC5see previoussheet2 v,1 v,2 v,3 v,41 t,1 t,2 v,5 v,6 v,7 v,8t ef

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 47Amendment A1:Contains:New design rules for:compressive strength perpendiculer to grainPresent rules unsafe31ll ef

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 48Amendment A1AdditionAxially loaded screwsTraditional screwsDiameter thread=smooth shankNot very effectivenot hardenedlow bending moment>8mm requires predrilled holes

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 49Amendment A1AdditionAxially loaded screwsVery effectivehardenedself tappinghigh axial stiffnessBackground:Blaß, HJ; Bejtka, I: Self-tapping screws as reinforcements in connections with dowel-type fasteners. In:Proceedings. CIB-W18 Meeting, Karlsruhe, Germany 2005. Paper 38-7-4Blass H.J. Joints with dowel-type-fasteners, In: Timber Engineering Thelanderson and Larsen, editors, Wiley &Sons (2003):

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 50

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 51Some examplesLeg or coach screw

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 52Some examplesSpax-SHeco Topix/FixRapid Komprex

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 53Tecfi WoodpeckerBMF TorxSFS WT

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 54Check:- Withdrawal failure- Tear-off failure of the head- Pull through of the head- Tensile failure of the screw- Torsional capacity- Group effect (neff number of effective fasteners)

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 55-Withdrawal: Code proposals in EU countries(1)Eurocode 5 = (1)R1,5( d l )0,8ax,a,k= π ⋅ ⋅ef2−33,6 × 10 ⋅ ρk⋅2sin a + 1,5 ⋅cosa(2)Rax;k=2k2−660×10 ⋅ ρ2sin a + ⋅cos43a⋅d⋅lef(3)(4)ax,k( 1,5 + 0, ⋅ d ) ⋅( l − d ) ⋅ ρR 6R=nom hec nom( π ⋅d⋅l)−33,0 × 10 ⋅ ρk⋅2sin a + 1,5 ⋅cos0,8ax,k= 1,7 ⋅1 ef2a

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 56Model uncertainty – evaluation of test resultsEurocode 525(1) (4) (2) (3)20Frequentie..151050-1 -0,8 -0,6 -0,4 -0,2 0 0,2 0,4 0,6 0,8 1ln(model/meetpunt)Current EC5 design rule unsafe

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 57New proposal in Amendment A1:RequirementScrews as defined in EN 145926 mm ≤ d ≤ 12 mmR0,9 0,80,52 d .lef⋅ρkax,a,k= nef22sina + 1,2 ⋅ cosaAll other screws:Rax,a,k=nefsin2fax.d.lefa + 1,2 ⋅ cos2 ρa ρka0,8Parameters determined by tests EN14592 (EN 1382)

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 58- Head tear off- Axial screw strength:Determine by tests:EN 14592 R- Torsional capacityEN 14592=A⋅axf ax

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 59Head pull throughEN 14592Test standard EN 1383Eurocode 5:R( ) ( ) )1 2 1 2⋅dk- ⋅ds⋅3,0⋅fc,90kRk= π ⋅22,=A⋅axf axZulassung Germany 9.1-235:Nk= 16,0⋅ dk2In the absents of information Clause 8.5.2. bolt washers

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 60•short elastisch behaviour•Large non-elastic traject

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 61Model uncertainty design rule 9.1-235andn Eurocode 5 for screwswith washers9Eurocode 5Zulassung876Frequentie543210-1 -0,5 0 0,5 1 1,5ln (model/meetwaarde)

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 62- Group (tear out) effect:Due to a lack of background informationBased on test by Gehri (empirical):n ef =n0,9

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 63Splitting by perpendicular to grain forcesF Edαbh ehF v,Ed,1F v,Ed,2b/2b/2ba) b)Design clause 8.1.4 (3) is formulated as a maximumshear force criterion on either side of the connectionBackground: Leijten A.J.M. & Vander Put T.A.C.M, Evaluation of Perpendicular to Grain Failure of Beamscaused by Concentrated Loads of Joints, In: Proceedings of CIB-W18, paper 33-7-7, Delft, 2000.

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 64Splitting by perpendicular to grain forcesDesign clause 8.1.4 (3) isformulated as a maximum shearforce criterion on either side ofthe connectionFracture mechanics background14 is calibration parameterw = (political factor)F90,Rk=14b w0,35 wplmax 100 for punched metalplate fastenersw = 11 for all other fastenershe he1− h

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 65Splitting by perpendicular to grain forcesSome empirical models considerFastener spacingFkksr 18a= kskr6.5+2 h1= max 1.4a0.7 + hn=2n h 1i=1 hi90,k2( tefh )0.8ft,90,k

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 66Splitting by perpendicular to grain forcesFracture mechanicalmodelConsider energybalance after crackappearance

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 67Splitting by perpendicular to grain forcesUK-Test results versus design proposalsStrength [N]500004500040000350003000025000200001500010000500000 0,2 0,4 0,6 0,8 1he/hTest ResultsEurocode 5 designPunched metal plate fasteners

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 68Comparison between modelsEurocode 5

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 69Splitting by perpendicular to grain forcesAssumed governing failure mechanism is shearNot by tensile stresses perpendicular to grainFor loaded edges>0,7 h no splittingh ehSimply supportedmax FCantilever beam max F/2Fhh eF/2

EUROCODESBackground and ApplicationsEN1995-1-1: Section 8 - ConnectionsBrussels, 18-20 February 2008 – Dissemination of information workshop 70Frequently heard:Not found in EurocodeWe don’t know everythingResearch in progressFuture changes and additions areexpected