=

OMMQ=

SWrucWural Analysis of HisWorical ConsWrucWions – Jerzy Jasieńko (ed) © 2012 DPNH ProcławH PolandH ISSN 0860-2395H ISBN 978-83-7125-216-7

TfjBbo mfNp ClNNbCTflNpW obifABfifTY lc BliTba glfNTp abpfdN oribp Carla CeraldiNI jaria iippielloOI bnnio ousso brmolliP

==

ABpToACT =qhe= use= of= timber= pins= in= connecting= timber= elements= is= a= valid= alternative= to= the= employment= of=metallic =devicesI =and =apart =from =being =quite =spread =in =prefabricated =timber =framesI =it =could =be =an =efficient= solution= in= the= field= of= restoring= timber= structuresK= qhe= design= rules= for= pinned= joints= are=universally= based= on= gohansen’s= theoryI= Eburopean= vield= jodelFI= but= their= application= to= timber=pegged= connections= still= shows= some= unsolved= problemsI= linked= toW= NF= dowelJbearing= strength;=OF=bending=strength=of=the=pin;=PF=shear=strength=of=the=pin;=QF=the=feasibility=of=the=fourth=failure=jode=of= bvjK= jany= studies= analysing=one= or= more=of= those=aspects= can=be= found= in= literatureI= but= there=isn’t=yet=an=analytical=formulation=alternative=to=this=on=which=the=bvj=is=basedK=Authors=are=carrying=on= an= extended= experimental= researchI= trying= to= better= understand= the= complex= mode= of= failure= of=timber= joints=connected=by=timber=pegsI=and=consequently=to= improve=design=rulesK=A=first=phase=has=involved=double=shear= plane= joints= of=glulam=fir=connected=by=ash=pinsI=varying=the= thickness=of= the=jointed=boardsI= and=so=pointing=out= the= role=of=bending=strengthK= fn=a= second=step= the= role=of= dowelJbearing= strength= has= been= investigatedI= choosing= as= base= material= three= wood= species= with= quite=different= densitiesK=kow=the=final=step=of= the=whole=research= is=presentedW=first=of=allI= the=role=of=pin=shear= strength=has=been=studied;= then=all=obtained=results=are=employed= in=analyzing=the=behaviour=of=double=shear=plane=jointsI=varying=the=wood=speciesI=and=its=transposition=in=using=design=rulesK==heywordsW Timber jointI Timber pegI aesign rules N. fNTolarCTflN N.N. Timber joints with timber pins qhe=use=of= timber=pins= in= connecting= timber= elements= is= quite=spread= in=realization=of=prefabricated=timber= framesI=but= it= could=be=envisaged=also= in= the= field=of= restoring=ancient= timber= structures= xNzI=avoiding=the=most=common=handicaps=of=current= jointing=methodsW=moisture=condensing=problems=in=the= interface= between= timber= and= steel= elements;= the= questionable= aesthetic= output= in= uncovered=structures;= the= difficult= reversibility= of= the= intervention= with= resin= adhesivesK= qhe= design= rules= for=pinned= joints= are= universally= based= on= gohansen’s= theoryI= named= buropean= vield= jodel= EbvjFI=which =assumes =a =perfectly =plastic =behaviour =for =the =connected =timber =elements =and =also =for =the =metallic=bolts=xOzK=A=summary=of=the=unsolved=problems=related=to=the=application=of=those=formulas=to=pinned=connections=and=specifically=to=tenon=and=mortise=joints= in=timber=frames=can=be=found=in=xPz=where= the= author= points= out= which= parameters= ought= to= be= modifiedW= NF= dowelJbearing= strength;=OF=bending=strength=of=the=pin;=PF=shear=strength=of=the=pin;=QF=the=fourth=failure=jode=of=bvjK=jany=studies= analysing= one= or= more= of= those= aspects= can= be= found= in= literatureI= but= there= isn’t= yet= an=analytical=formulation=alternative=to=this=on=which=the=bvj=is=basedK=

================================================N=Carla=CeraldiI=mhaI=Assistant=mrofessorI=rniversity=of==kaples=±cederico=ff”I=aepartment=of=Construction=

and=jathematical=jethods=in=Architecture=ECljjAFI=ceraldi]uninaKit=O=jaria=iippielloI=mhaI=rniversity=of==kaples=±cederico=ff”I=aepartment=CljjAI=mariaKlippiello]uninaKit=P=bnnio=ousso=brmolliI=cull=mrofessorI=rniversity=of==kaples=±cederico=ff”I=aepartment=CljjAI=

russermo]uninaKit=

=

OMMR=

Authors= of= the= present= study= are= carrying= on= an= extended= experimental= researchI= trying= to= better=understand=the=complex=mode=of=failure=of=timber=joints=connected=by=timber=pinsK=A=first=phase=of=this=research= has= involved= double= shear= plane= joints= of= glulam= fir= connected= by= ash= pinsI= varying= the=thickness=of=the= jointed=boardsI= xQzK=qhe=comparison=of=experimental=results=with=the=analytical=ones=coming= out= employing= design= formulas= prescribed= by= burocode= R= xRzI= has= shown= that= the=different=nature= of= the= material= used= for= the= connecting= device= requires= a= more= specific= definition= of= the=±yielding=moment”=of=the=pinI=which=must=be=inserted=in=the=formulasK=joreoverI= it=has=been=noticed=that =failure =loads =given =by =gohansen’s =formulas =for =the =three =tested =samples =of =double =shear =plane =joints= don’t= diverge= significantly= from= the= experimental= onesI= when= the= collapse= mode= involves=bending=of=the=pinK=fnstead=the=theoretical=and=experimental=data=show=absence=of=matching=in=those=joints=characterized=by=a=large=ratio=between=the=diameter=of=the=timber=pin=and=the=least=thickness=of=the=connected=timber=boardsK=qhenI=xSz=a=deeper=insight=on=the=definition=of=dowelJbearing=strength=of=the=timber=elements=of=a= jointI=when=using=a=timber=pinI=has=been=thrownK=qhe=experimental=work=has=been= done= on= three= wood= species= characterized= by= different= values= of= densityW= pawloniaI= fir= and=durmastI =using =an =ash =timber =pin =with =diameter =equal =to =PM =mmK =qhe =interpretation =of =experimental =data=has=allowed=the=proposition=of=a=simplified=rheological=modelI=starting=from=the=springsJinJseries=model= envisaged=by=pchmidt= xOzI= which=can=better= and= easier= identify= the=yielding=phase= in=dowelJbearing=testsK=joreoverI=the=use=of=the=proposed=model=allows=approximating=from=below=the=yielding=value=for=each=wood=species= with=the=limit= strength=value=in=confined=compression=test= of=the=timber=pinK=po=the=envisaged=model=gives=to=this=mechanical=characteristic=of=the=timber=pin=a=central=role=in=defining=the=dowelJbearing=strengthK=

N.O. phear strength of the timber pin and its role in double shear plane joints qhe= already= obtained= results= show= how= the= different= nature= of= the= material= employed= for= the=connecting=means= requires= a= more=specific= study=of= the=rupture=corresponding= to=jode=fsI= the= one=characterizedI=in=gohansen’s=theoryI=by=the=presence=of=double=plastic=hinges=in=the=dowelK=fn=factI=the=timber=peg=portion=crossing=the=shear=plane=shows=shear=slipping=as=well=as=bending=deformationK=qhe=extension= of= the= segment= carrying= the= yielding= shearJbending= stress= varies= depending= upon= the=thickness=of=the=timber=boards=as=well=as=the=rate=between=the=densities=of=the=wood=species=of=which=boards= and=pegs= are=madeK=qhe=double=shear= plane= joints= tested=have=been=designed=to=avoid=cutting=shear=rupture=of=the=timber=pinsI=obviously=absent= in=the=gohansen’s=model=with=metallic=pinsK=po=one=aim=of=the=present=phase=of=the=research=is=understanding=in=which=case=the=presence=of=shear=is=really=relevant= in= the= definition= of= the= design= value= of= the= loadI= and= how= it= combines= with= the= other=mechanical=parameters= Ebending=strength=of= the= timber=pinI= dowelJbearing=stress=of= the= jointF=which=must=be=taken=in=accountK=qhe=experimental=study=can=be=summarized=as=followsW=

– tests= on= a= single= ash= peg= has= been= made= with= a= testing= apparatus= designed= by= pchmidt= xTz= to=evaluate=the=shear=behavior=of=the=peg=varying=the=shear=span;=

– further=double=shear=plane=joints=have=been=tested=choosingI=as=base=materialI=wood=species=with=more= densityI= durmastI= and= less= densityI= pawloniaI= than= firI= already= employed= in= xQzI= to= cause=changing=of=the=shear=span=into=the=jointK=

O. CeAoACTbofwATflN lc tlla pmbCfbp bjmilYba

O.N. Characterization of wood species chosen for boards qhe=choose=of=wood=species=for=experimentation=has=been=oriented=towards=those=which=can=be=more=frequently= found=in=ancient= timber= structuresI= especially= in=covering= onesI= as=employment=of= timber=pins=in=restoring=ancient= timber=structures=isI=as=already=saidI=one=of=the=task=which=has=motivated=the=present=researchK=At=this=aimI=oak=woodI=specifically=a=durmast=Enuescus=petraeaF=of=high=density=and=fir= wood= EAbies= albaF= have= been= used= in= the= experimental= programK= Another= woodI= mawlonia=Emawlonia=tormentosaFI=generally=unemployed=for=structural=purposes=as=it=is=used=in=furniture=industryI=has=been=chosen=because=of=its=quite=low=densityK=qhis=has=been=done=to=enlarge=the=spectrum=of=ratios=between= the=density= of= the= wood= of=which= the=pin= is= madeI= ash= Ecraxinus= excelsiorFI= and= the=wood=species= of= the= timber=boards= constituting= the= jointI= as= rate= in=densities=plays= a= relevant= role= in= joint=behavior=xQI=SzK=jean= and= characteristic= values= of= density= and= parallel= to= grains= compressive= strength= for= all= wood=species=are=quoted=in=qable=NK=

=

OMMS=

Table N jean=and=characteristic=values=for=boards=wood=species==

= mawlonia cir aurmast jean= Characteristic= jean= Characteristic= jean= Characteristic=

aensity EkgLmPF= OSO= NVS= QQT= PVO= TOS= SPU=

Compression EjmaF= NVKRS= NPKVR= PUKNT= PNKVR= RNKNR= QUKMM=

=qhe=mechanical=characteristic=of=dowelJbearing=strength=with=steel=bolt=shb=and= with= timber= pin=shpI=measured=using=the=halfJhole=set=up=of=Apqj=RTSQ=xUzI=employing=a=bolt=with=PM=mm=of=diameterI=is=quoted=in=qable=OK==

Table O==jean=dowelJbearing=strength=with=steel=bolt=and=timber=pin==

= mawlonia cir aurmast

σ hb EjmaF=

NQKRS== ONKOS= QNKUS=

σ hp EjmaF=

NOKTN= NQKSO= NRKSN=

=fn=xSz=a=simplified=model=schematizing=dowelJbearing=behaviour=is=derivedI=where=two=linear=phases=are=connected=by=a=transition=phaseK=qhe=first=linear=phase=ends=in=correspondence=of=the=load=value=cc=for=which=yielding=of=the=peg=occursI=Ewhich=for=the=ash=peg=tested=is=OOIQPV=kFI=and=it=has=the=slope=of=the=diagram=of=the=timber=pin=confined=compression=testK=Adding=to=the=deformation=just=obtained=that=corresponding=to=the=value=cc=of=the=applied=load=in=the=diagram=of=dowelJbearing=test=with=steel=boltI=the=end=of=the=transition=phase=is=obtainedK=qhe=second=linear=phase=has=the=slope=of=the=diagram=of=the=springsJinJseriesJmodelI= which= is= obtained= adding= deformations= of= the= timber= pin= in= confined=compression=test=to=those=of=the=base=material=dowel=bearing=test=with=steel=boltK==O.O. Characterization of ash timber qhe=pins=have=been=made=of=ash=timberI=already=employed=in=the=other=phases=of=the=research=xQI=SzI=in=which=the=mechanical=characteristics=quoted=in=qable=P=have=been=determinedK==

Table P jean=and=characteristic=values=for=ash=timber==

= Ash = jean Characteristic

aensity EkgLmPF= SRO= RTO=

marallel to grain compression EjmaF= RSKOV= QVKQO=

Bending EjmaF= NNOKQU= UQKSN=

Cutting phear EjmaF= PNKVM= OPKUS=

oadial confined compression EjmaF= NOKQT= –=

=2K2K1K phear behaviour of the ash pin pear=behavior=of=the=pin=has=been=extensively=studied=by=pchmidt=xTI==VzI=who=proposed=the=addiction=of= another= failure= modeI= jlab= sI= to= those= envisaged= by= gohansenI= to= take= in= account= an=experimentally= observed= phenomenonK= ee= named= this= additional= yield= mode= ±effective= peg= shear”=which=is=a=combination=of=peg=shearingI=peg=bending=and=peg=dowelJbearing=yieldingK=ee=also=asserted=that= a= flexural= plastic= hinge= develops= only= exceptionally= in= the= pegI= as= a= secondary= effect= after=effective=shear=yieldingI=and=that=jlab=fs=of=gohansen’s=theory=can’t=develop=before=effective=shearI=in=the=usual=configurations=of=tenon=and=mortise=joints=he=studiedK=

=

OMMT=

At= the=aim= of= studying=the= shear= behavior= of= the=ash=pin= inside= the= jointI= a= test= apparatus=has=been=realized=following=pchmidt=indicationsK=qwo=steel=blocks=have=been=made=to=hold=the=peg=laterallyI=and=a=third=oneI=put=in=the=middle=of=the=spanI=allows=load=transmission=EcigK=NFK==

cig. N=phear=test=on=the=peg==

qhe=free=span=”a”I=that=is=the=distance=between=the=lateral=steel=block=and=the=central=one=on=each=side=of= the= specimenI= has= been= chosen= varying= from= TIR= mm= to= UTIR= mmI= assuming= nine= values=characterizing=nine=corresponding=samplesI= each=constituted=by=three=specimensK=qhe=peg=diameter= is=always=of=PM=mm=and=the=length=is=that=sufficient=for=an=efficient=clampingK=qests=have=been=made=with=an=electronic=board=universal=load=machineI=in=displacement=controlI=pun=RI=produced=by=daldabiniI=with=a=maximum=load=of=RM=kkK=qested=specimens=have=been=conditioned=in=an=ambient=with=temperature=of=OM=–O°C=and=relative=humidity=of=SR=–R=BK=qhe= mean= values= of= yielding= force= and= corresponding= displacement= are= listed= in= qable= QI= and= the=corresponding=diagramsI=representative=for=each=sampleI=are=quoted=in=cigK=OK===

=

cig. O=phear=test=on=the=peg=diagrams=varying=free=span=±a”==

Table 4 jean=values=of=the=yielding=force=and=corresponding=displacement==

= cree span “a” EmmF UT.R TR SO.R RM PM OO.R NR NN T.R

Yielding corce EkkF= NMKM= NOKO= NOKN= NOKS= NRKP= NRKP= NRKT= NTKU= OMKO=

aisplacement EmmF= SKT= UKR= SKS= SKS= PKV= QKQ= PKN= PKO= QKP=

=

OMMU=

qhe= tests= results= show= how= the= reduction= of= the= shear= span= induces= a= sensible= turning= of= the=deformation=mode=of= the=peg=from=the=prevalence=of= bending=effects= to= that= of= shear= slippingI=with=a=consequent= very= strong= hardening= after= the= first= yielding= valueK= fn= detailI= that= changing= in=deformation=mode=appears=when=the=shear=span=±a”=is=less=than=peg=diameterI=as=for=±a”=larger=or=equal=to=aI=a=quite=classical=bending=deformation=can=be=observedK==2K2K2K jean value of the yielding bending moment of the ash peg A=sample=of=cylindrical=ash=pegs=with=a===PM=mmI=constituted=by=ten=specimensI=has=been=tested=with=the=test=settlement=Erkf=bk=QMUF=envisaged=to=measure=bending=strengthI=using=a=clear=span=of=NU=h=Eh=being= the= specimen= cross= section= heightFI= with= load= applied= at= OLP= of= the= spanK= ppecimens= have=nominal=dimensionsW=a===PM=mmI=i===RQM=mmK==qhe=yield= limit= for= each=test= has=been=determined=using=the=procedure=called=RB=offset= described= in=Apqj= RTSQI= which= envisages= the= choiceI= as= limit= yielding= pointI= of= the= intersection= of= the= loadJdisplacement= curve= with= a= straight= line= parallel= to= the= linear= part= of= the= diagramI= translated= to=a =distance =equal =to =RB =of =the =diameter =a =of =the =boltK =qhe =sample =mean =yielding =stress =is =fbIm= ==VTKTM=jmaI=to=which=corresponds=the=yielding=bending=moment=mean=value=jyIm===ORUIUQM=kmmK==P. alrBib pebAo miANb glfNT TbpTp

P.N. bxperimental program description At= the= aim= of= studying= the= behaviour= of= double= shear= plane= joints= with= varying= ratio= between= the=densities=of=the=timber=employed= for= the=jointed=boards=and=that=of=which=the=peg= is= madeI= two=more=species= have= been= chosenI= durmast= and= pawloniaI= to= compare= results= with= those= obtained= with= fir=in=xQzK=qhe=ratios=between=characteristic=values=of=density=of=pawloniaI= fir= and=durmast= to=that=of=ash=are=MIPQI=MISR=and=NINOI=respectivelyK==po=two=samplesI= each=constituted=of=three=specimensI=have=been=made=of=the=same=dimensions=of=the=qvmb=C=tested=in=xQzW=boards=have=the=same=lateral=dimensionsI=OMM=×=PMM=mmI=and=are=joined=by=a= peg= of= PM= mm= in= diameterI= disposed= in= the= middle= of= the=boardsI= so= respecting= end= distances=prescribed=by=the=burocode=R=in=case=of=steel=boltsW=Ta=from=the=loaded=sideI=Pa=from=the=lateral=sideI=where= a= is= the= bolt= diameter;= thickness= of= the= lateral= and= middle= boards= are= tN= == SM= mmI=tO===VM=mmI=respectivelyK=Compression= load= tests= have= been= made= with= the= electronic= board= universal= load= machineI= in=displacement= controlI= pun= RK= qhe= simultaneous= registration= of= compressive= load= and= of= the=corresponding= slipping= of= the= middle= board= under= loadI= has= been= doneI= with= a= load= cell= of= RM= kk=capacity =and =an =isaq=of =RM =mm=of =maximum=strokeI =respectivelyK =qhe =two =transducers =have =been =connected= to= an= electronic= power= station= with= QM= channels= distributed= by= sfpeAv=jbAprobjbkqp=dolrm=EcigK=PFK==

==

cig. P=aouble=shear=plane=joints=test=for=pawlonia=and=durmast==

fn=cigK =Q =the=most =representative=diagram=for =each=sample=plus=that =of =fir =are =quoted; =they=are=those=obtained=measuring=the=slipping=of=the=middle=board=under= loadI=and=not=the=global=displacementI=to=better= reproduce= the= deformation= due= to= the= jointing= system= Epeg= behavior= combined= with= dowel=bearing=capacity=of=the=timber=boardsFK=

=

OMMV=

=

cig. 4=ioadJslipping=diagrams=of=the=double=shear=plane=joints=tests==qhe=yield=limit=for=each=test=has=been=determined=using=the=RB=offset=procedure=already=describedK=qhe=yield=limit=values=and=the=corresponding=slipping=valuesI=as=well=as=the=ultimate=values=for=each=timber=are=quoted=in=qable=RK==

Table R vielding=forceI=corresponding=slipping=displacement=and=ultimate=values==

pample= vielding==load= vielding=displacement=

rltimate=load= rltimate=displacement=

= k= mm= k= mm=

mawlonia= OSIVSR= SKRSU= OVIMQM= PMKNMS=cir= OTIRNO= PKRSO= QMISTO= NRKMMT=

aurmast= PPIRMUN= QKSUT= RMIOVT= NOKNQO= P.O. Analysis of results cirst=of=allI=some=observations=about=the=failure=mode=of=the=double=shear=plane=jointsI=andI=in=detailI=that=of=the=timber=pegI=can=be=doneK=qhe=broken=joint=and=the=corresponding=peg=are=quoted=in=cigK=RK=

cig. R=aouble=shear=plane=joints=failure=modes=

=

OMNM=

qhe=chosen=ratio=between=the=thickness=of=the=boards=and=the=diameter=of=the=peg=doesn’t=allow=cutting=shear= failure= of= the= pegK= joreoverI= the= first= two= failure= modes= envisaged= by= gohansen’s= theoryI= in=which=only=the=dowel=bearing=strength=of=the=timber=constituting=the=boards=plays=a=relevant=roleI=are=not=feasible=when=a=timber=peg=takes=the=place=of=the=steel=bolt=in=a=joint=with=thickness=of=the=boards=larger=than=pin=diameterK=po=it’s=not=surprising=that=the=failure=mode=is=that=characterized=by=bending=of=the=pegI=with=the=envisaged=combination=of=factors=which=influences=itW=dowel=bearing=strength=of=base=materialI=shear=and=bending=behavior=of=the=timber=pegI=density=ratio=of=the=employed=wood=speciesK=fn=detailI=the=pawlonia=boards=show=a=relevant=dowel=bearing=deformation=of=the=holesI=and=the=ash=peg=breaks= with=classical=bending= featuresI= such=as= the= fracture=of= the= fibers= under= tensile=stressesK= After=the =first =yielding =value =has =been =reachedI =no =more =carrying =capacities =can =be =seenI =see =forceJdisplacement=diagram=in=cigK= QK= po= the=deformation=of= the=holes=allows=bending=of= the=peg=and= the=joint= failure=mode=can=be=assumed=as= that= corresponding= to=the=fff=jode=of= gohansen’s= theoryK=qhe=shear=spanI=measured=on=the=deformed=pegI=is=a===OP=mmI=whichI=looking=to=diagrams=quoted=in=cigK=OI=ought= to=identify=an=intermediate=behavior= in=between=the=curves=corresponding=to=±a”===PM=mm=and=±a”===OOKR=mmI=in=which=the=role=of=shear=deformation=is=quite=ineffectiveK==cir=joints=have=shown=an=appreciable=deformation=of=the=holesI=which=is=a=consequence=of=its=density=being=less=than=that=of=ashI=butI=as=the=difference=is=not=so=large=as=in=pawlonia=caseI=the=timber=peg=is=more=confined=in=its=deformation=in=correspondence=of=the=shear=planesK=Consequently=the=deformation=mode=of=the=peg=is=more=similar=to=the=fs=jode=of=gohansen’s=theoryI=even=if=the=two=deformed=zones=in =shear =planesI =which =ought =to =correspond =to =±plastic =hinges”I =can =be =assimilated =to =those =corresponding=to=shear=span=±a”=due=to=shear=slipping=occurrenceK=fn=fir=double=shear=plane=jointsI=the=peg =has =shown =a =value =a == =NR =mmI =andI =looking =to =the =diagram=for =this =value =of =±a” =in =cigK =OI =the =contribute=of=shear=slipping=in=determining=the=deformation=behavior=of=the=peg=can=be=recognizedK=qhe =first =yielding =of =the =fir =joints =is =marked =andI =after =the =yielding =phaseI =there =is =a =large =plastic =hardening= oneI= while= pawlonia= joints= have= shown= a= perfectly= plastic= behaviorK= qhe= yielding= force=values =for =fir =and =pawlonia =are =quite =near = =andI =as =fir =shows =a =great =bearing =capacity =after =this =first =yieldingI= it’s=possible= envisaging=that= this=yielding=is= determined=by=the=relevant=deformation=of= the=timber=peg=inside=the=deformed=base=materialK=aurmast=joints=behavior=could=be=schematized=as=linear=hardeningI=the=yielding=phase=is=not=evident=at=allI=see=cigK=QI=and=this=very=different=behavior= is=of=course=determined=by=the=density=valueI=which=is=larger= than= that= of= ashK= cailure= has= occurred= without= appreciable= dowel= bearing= deformation= of= the=holesI=the=timber=peg=shows=a=small=extension=of=the=shear=spanI=a===Q=mmK=poI=even=if=at=the=end=the=peg=shows=broken=tensile=stressed=fibers= in=the=middleI=localization=of=shear=deformation=in=the=shear=planes= is=evidentI=and=it=could=forecast=a=cutting=shear=failureK=kone=the=lessI=the=failure=mode=is=that=corresponding=to=bending=of=the=pegI=as=it=appears=before=cutting=in=shear=planes=can=occurK=then=the=density=of =the=timber=constituting=the=boards=is =larger =than=that =of =the=peg=woodI =as =in =the=case=of=durmastI=the=more=confined=timber=pin=is=more=contrasted=in=its=bending=deformation=inside=the=boardsI=as=already=observed=in=studying=dowel=bearing=strength=with=timber=pegI=xSzK=

P.P. Comparison between theoretical and experimental results qheoretical=results=can=be=obtained=applying=design=formulasI=based=on=gohansen’s= theoryI= envisaged=for=double=shear=plane=joints=with=steel=boltI=quoted=in=qable=SI=where=tNI=tO=are=timber=thickness;=fhINId=EfhIOIdF=is=dowel=bearing=strength=in=tNI=EtOF;=b=is=the=ratio=fhIOId=L=fhINId;=dW=bolt=diameter;=jyIdW=yield=bending=moment=of=the=boltK=qhe= employement= of= those= formulas= needs= the= definition= of= two= mechanical= characteristicsW= dowel=bearing=strenght=of=the=joint=with=timber=pegI=instead=of=steel=boltI=and=yielding=bending=moment=of=the=timber =pegK =fn =the =present =caseI =the =first =oneI =for =each =timberI =can =be =taken =from=the =second =raw=of =qable =OK =cor =what =concerns =jyI= yielding=bending= momentI= two= different= values= will= be= inserted= in=design=formulasW=

– jyIN= == OMOISQQ= kmmK= qhis= is= the= valueI= already= employed= in= xQzI= which= has= been= calculated=inserting= the= mean= compressive= strength= of= ashI= quoted= in= qable= PI= fcIMIm= == RSKOV= jmaI= in= the=evaluating= formula= given= by= buroicode= RW= jyIk= == MKUfuIkaPLSK= qhis= procedure= is= justified= as= the=transition= to= the= plastic= phase= in= clear= timber= subjected= to= bending= loads= is= characterized= by= the=overcoming=of=the=parallel=to=grains=compressive=strength=elastic=limitI=on=the=compressed=sideI=xNMzK=

– jyIO===ORUIUQM=kmm=obtained=in=paraghraph=OKOKOK=qheoretical= values= so= obtained= are= quoted= in= qable= T= and= qable= UI= respectivelyI= where= values= of=yielding=forces=are=doubled=to=be=compared=with=experimental=values=of=qable=RK=

=

OMNN=

Table S==aesign=formulas=of=bolts==

jode= od===meg=aesign=ptrength= == k= =f= dtf dh NINI =

ff= bdtf dh OINIRKM =

fff=( ) ( )

úúû

ù

êêë

é-

+++

+b

bbbb

b ONINI

ININI OQNO

ONKN

dtfjdtf

dh

dydh =

fs=dfj dhdy INIIO

NONKNbb+

=

=Table T==gohansen’s=yielding=force=valuesI=EkFI=for=jyIN=

=

pample= oN oO oP o4 mawlonia QRITRS= PQIPNT== OPIROU= OTIPQV=cir ROISPO= PVIQTQ== OSINOR= OVIPPO=aurmast RSINVS= QOINQT= OTIQSR= PMIPMV=

=Table U==gohansen’s=yielding=force=valuesI=EkFI=for=jyIO=

=

pample= oN oO oP o4 mawlonia QRITRS= PQIPNT== ORIOMV= PMIVMV=cir ROISPO= PVIQTQ== OTIUQP= PPINRM=aurmast RSINVS= QOINQT= OVIOMM= PQIORM=

=A= good= matching= with= experimental= results= of= the= theoretical= results= quoted= in= both= tables= can= be=observedI= better= in= qable= U= where= the= mean= value= of= the= yielding= bending= moment= has= been=determined=experimentallyK=As=theoretical=results=approximate=the=experimental=ones=from=belowI=their=employment=in=designing=joints=is=safer=as=much=as=larger=is=the=ratio=between=densities=of=base=timber=to=timber=of=which=the=peg=is=madeK=poI= inserting= the= real= dowel= bearing= strengthI= which= takes= in= account= the=deformation= of= the= timber=pegI=and=the=mean=values=of=yielding=bending=moment=of=the=peg=as=previously=calculatedI=the=design=formulas=based=on=gohansen’s=theory=can=be=confidently=employed=also=for=double=shear=plane=joints=with=timber=pinsI=when=timber=boards=thickness=is=larger=than=peg=diameterK=qhe= failure= mode= given= by= theoretical= formulas= is= that= corresponding= to= fff= jodeI= single= ±plastic=hinge”=in=the=middle=of=the=pegI=which=can’t=reproduce=the=complexity=of=the=experimentally=observed=failure=modeI=but=which=synthetizes=the=final=evidenceI=that=is=the=bending=failure=of=the=pegK==4. ClNCirpflNp =qhe= long= research= work= doneI= of= which= that= presented= here= is= only= the= last= phaseI= allows= the= final=statement= that= the= design= formulas= based= upon= gohansen’s= theoryI= and= given= by= the= burocode= R= to=design=joints=with=steel=boltsI=can=also=be=employed=to=dimension=timber=joints=with=timber=pinsI=when=the= peg= diameter= is= smaller= than= jointing= boards= thickness= Eas= it= presumably= will= be= the= case= in=restoring=timber=structuresFI=with=the=following=recommendationsW=

– the= dowel= bearing= strength= value= can’t= be= that= obtained=using= steel= bolt= and=usually= quoted= in=literatureI=but=it=must=be=referred=to=experimental=results=corresponding=to=the=chosen=species=for=boards =and =peg =timbersK =As =suggested =in =xSzI =a =simplified =procedureI =which =offers =an =approximation=from=belowI=can=be=followedI=which=only=requires=the=experimental=determination=of=the=radial=confined=compressive=strength=of=the=timber=peg;=

– the=yielding=bending=moment=of=the=timber=peg=can=be=obtainedI=as=proposed=in=xQzI=adopting=the=theoretical=model=quoted=by=burocode=R= for= the=steel=boltI= substituting= in= it= the=tensile=strength=value=with=the=axial=compressive=strength=of=the=timber=of=which=the=peg=is=madeK=lf=courseI=if=an=

=

OMNO=

experimental=evaluation=of=this=mechanical=characteristic= is=allowableI= the=yielding=force=values=predicted=by=the=formulas=will=be=more=accurateK=

obcbobNCbp xNz= CeccottiI= AKI= BonaminiI= dKI= ouffiniI= jKI= rzielliI= iK= ENVVUF= oestauro conservativo di capriate

ligneeK ia mieve di pan jarinoK=qorinoI=CKiKrKqK=xOz= gohansenI=hKtK= ENVQVF=qheory=of= timber=connectionsK= fnternational Association for Bridge and

ptructural bngineering VW=OQVJOSOK=xPz= pchmidtI=oK=gK=EOMMSF=qimber=pegs=–=Considerations=for=jortise=and=qenon=joint=designK=ptructure

magazine PW=QQJQTK=xQz= CeraldiI= CKI= jormoneI= sK= and= ousso= brmolliI= bK= EOMMUF= oestoring= of= timber= structuresW=

connections= with= timber= pegsK= fnW= mrocK Sth fntK ConfK on ptructural Analysis of eistoric Construction pAeCM8IBathI=rniversity=of=BathI VNRJVOMK=

xRz= burocode=R=ENVVRF=mrogettazione delle strutture in legno – oegole generali per gli edificiK ErkfJbks=NKNFI=rkfK=

xSz= Ceraldi=CKI=iippiello=jKI=ousso=brmolli=bK==EOMNNF=Connections=with=timber=pinsW=the=influence=of=dowel=bearing=strengthK=fnW=mrocK fntK ConfK on ptructural health Assessment of Timber ptructures peATfp’11I=iisbonI=iaboratorio=kacional=de=bngenharia=CivilI=ppK=NJNNK=

xTz= pchmidtI= oK= gK= and= jacheyI= oK= BK= ENVVTF= Timber crame Tension goineryK= oesearch= oeportI=rniversity=of==tyomingI=aepartment=of=Civil=and=Architectural=and=bngineeringK=

xUz= Apqj=a=RTSQ=–=VTaK=EOMMTF=ptandard Test jethod for bvaluating aowelJBearing ptrength of tood and toodJBased mroductsK=Apqj=fnternationalK=

xVz= jillerI=gKhKI=pchmidt=oKgK=and=Bulleit=tKjK=EOMNMF==kew=vield=jodel=for=tood=aowel=ConnectionsK=gournal of ptructural bngineering=ApCb=lctoberW=NORRJNOSNK=

xNMz=diordanoI=dK=EOMMRF=Tecnica delle costruzioni in legnoK=s bdK=jilanoI=elbmifK=