eobofpflk=lc=boebk=bibbkpK== =lmofplk=btbbk=boe=ilh ... · UQP=...

=

UQN=

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

=CeAoACTbofpATflk=lc=bAoTebk=bibMbkTpK==A=ClMmAofplk=BbTtbbk=bAoTe=BilCh=MAplkovI=oAMMba=bAoTe=Aka=ClB= iorenzo jiccoliNI rrs jüllerO ABpToACT==barth=represents=one=of=the=oldest=construction=materialsI=which=are=still=utiliòed=both=in=developed=and=developing= countriesK= thile= research= on= stone= and= brick= masonry= has= recently= benefited= from=significant=advancesI=knowledge=on=the=material=properties=and=failure=mechanisms=of=earthen=building=construction=is=limited=and=fragmentedK=fn=this=paper=a=comparison=of=the=mechanical=performance=of=structural=elements=built=in=adobe=Eearth=blockF=masonryI=rammed=earth=and=cob=is=presentedK=barth=can=be=processed=in=many=waysI=the=three=construction=techniquesI=howeverI=represent=the=most=important=typologiesI= which= constitute= totally= different= properties= based= on= differences= in= their= granulometryI=moisture=state=during=preparationI=homogeneityI=structural=performanceI=additive=or=stabiliserK=fn=order=to= gain= better= knowledge= on= the= structural= behaviour= an= extensive= compression= and= diagonal=compression= EshearF= tests= campaign= was= performedK= auring= diagonal= compression= experimentsI=a=technique=based=on=a= photogrammetric= system=was= applied= in=order= to= monitor= deformationK= cirst=compression= results= show= brittle= mechanical= behaviour= in= the= case= of= adobe= masonry= and= rammed=earth=elementsI=whereas=cob=exhibits=a=very=different=stressJstrain=patternW=cob=can=deform=beyond=the=elastic=range=with=a=gradual=drop=in=capacityK=qhis=behaviour=is=strongly=influenced=by=the=presence=of=fibresK=aespite=its= low=compressive=strengthI=cob= thus=presents=a= relatively=good=performance=within=the=earthen=material= range=as= far= as= shear= behaviour= is= concernedK= qhis=parameterI= together= with= its=long=postJpeak=plastic=phaseI=is=relevant=if=its=use=in=seismic=areas=is=consideredK=qhe=study=is=part=of=our= work= in= the= framework= of= the= ongoing= project= kfhbo= funded= by= the= buropean= `ommission=dealing=with=improving=immovable=`ultural=eeritage=assets=against=the=risk=of=earthquakesK==heywords: barthen materialsI Compression testI aiagonal compression test ==NK fkTolarCTflk==ft=is=estimated=that=PM=to=QMB=of=the=world=population=currently=lives=or=works=in=structures=built=in=or=with= earthK= barth= structures= require= high= maintenance= as= they= are= prone= to= erosion= under= rainfallI=spalling= and= crossJsectional= reduction= when= salts= are= transported= by= capillary= actionI= and= are= also=susceptible=to=cracking=both=under=low=tensile=and=low=compressive=stressesK=then=these=dwellings=are=located= in=regions= with=high=earthquake=riskI= their= intrinsically= low=resistance= to=dynamic=actions= is=further=worsened=by=such=durability=issuesK=A=number=of=construction=and=repair=practices=negatively=affect=earthen=buildings=and=make=them=susceptible=to=high=damage=even=under=low=seismic=forces=xNzK=iack=of=continuity=at=corners=and=at=wall=junctionsI=the=presence=of=heavy=roofs=that=are=not=supported=by= ring= beamsI= and= also= that= roofs= are= often= not= connected= to= walls= are= some= typical= recurring=examplesK= pome= countries= where= the= populationI= particularly= the= rural= oneI= still= inhabits= earthen=building=have=been=affected=by=highly=destructive=earthquakesI= for= instance=qurkey=Ebròinkan=NVVOFI=fran= EBam=OMMPFI= meru= Emisco=OMMTFI= `hile= E`onception= OMNMFK= Although= damage= to= dwellings= and=their= collapse= is=usually= the=cause=of=human= lossesI= earthquakes= are=as=well= devastating=to= the=built=cultural=heritage=in=these=regionsK=As=a=matter=of=factI=it=is=often=overlooked=that=a=considerable=amount=

================================================N=mhaI=BAj=cederal=fnstitute=for=jaterial=oesearch=and=qestingI=lorenòoKmiccoli]bamKde=O=mhaI=`Bf=pwedish=`ement=and=`oncrete=oesearch=fnstituteI=pwedenI=ursKmueller]cbiKse=Eformerly=BAjF=

=

UQO=

of=heritage=sitesI=of=which=many=are=endangeredI=are=built=in=earthK=pome=vernacular=earthen=building=techniques=are=no= longer= in=practiceI=and=the=knowledge=of=how=to=build= in=such=materials=has=been=lostK=barthen=techniques=considerably=differ=as=far=as=material=composition=and=construction=methods=are= concernedK= thile= some= guidelines= and= standards= for= building= with= earthen= materials= do= exist= as=Apqj=bOPVO=L=bOPVP=j=xOzI=fpNPUOT=xPz=and=kqb=bKMUM=Adobe=xQzI=these=often=lack=design=chartsK=joreoverI=values=specified=do=not=take=the=high=variability=of=earthen=materials=in=terms=of=mechanical=properties= into= considerationI=which= is=dependent= on=a= number= of=parameters= affecting=physical= and=chemical= bonds= at= microstructural= levelI= eKgK= granulometry= or= fibre= content= xRzI= compaction= and=moisture=contentK==kewly=introduced=seismic=regulations=for=countries=where=earthen=buildings=are=still=present=within=the=built= environment= EjoroccoI=makistanF=are=often=based=on=those=of=developed=countries=and= exclude=earth=as=a=building=materialK=then=seismic=regulations=for=earthen=buildings=do=exist=Ekew=wealandFI=these=tend=to=group=all=earthen=materials=into=oneK=fn=additionI=they=are=relevant=to=newJbuild=and=not=to=existing=historic= structuresK= oepair= and=retrofitting=of= earthen=structures=are=often=carried=out= without=being=recorded=and=when=based=on=elastic=stiffness=designI=additional= elements= introduced=are=being=found=to=be=too=stiff=in=comparison=with=earthen=materialsK=lbservation=in=most=recent=earthquakes=and=in=shaking= table= tests= suggests= that= the= introduction=of= concrete= xSz=or= steel= elements= xTz= as= well=as=retrofitting= with= steel= mesh= and= cement= plaster= xSz= negatively= affects= the= behaviour= of= earthen=structures= under= seismic= loadingW= stiffer= elements= attract= more= load= and= pound= the= original= earthen=building=elements=to=the=groundK=qhus=even=simple=repair=measures=which=might=have=been=introduced=with=the=original=intent=of=improving=the=behaviour=of=the=building=under=static=loads=might=harm=the=structure=under=dynamic=loadsK=kumerical=modelling=provides=an=effective=tool=by=means=of=which=the=behaviour= of= earthen= buildings= and= typical= damage= typologies= under= seismic= loading= can= be=understood= furtherI= and= by= means= of= which= retrofitting= proposals= can= be= assessed= before= being=adoptedI= but= sufficient= material= characterisation= to= use= as= input= to= numerical= models= is= currently=missingK=thile=some=models=for=earthen=structures=can=be=builtI=their=correlation=to=realJlife=situations=or=experiments=as=a=means=of=validation=has=yet=to=be=thoroughly=analysedK==OK AfMp=Aka=lBgbCTfsbp==fn=comparison=to=recent= advances= in=research=on=stone=and=brick=masonryI= knowledge=on=the=material=properties= and= failure=mechanisms= of= earthen= materials= is= limited= and=scattered= xUzK=qhe=current= paper=focuses=on=the=determination=of=material=parameters=and=the=behaviour=of=earthen=panels=and=other= test=specimens= under= different= loading=conditionsK= qhe= entire=experimental=program=was= performed= in= the=laboratories=of=BAjI=dermanyK=qhe=types=of=wall=segments=considered=in=the=experiments=consist=of=one=leaf= adobe= masonry= with= earthen= mortar= and= of= monolithic= rammed= earth= and= cob= walls= EqabK= NFK=fnvestigations=were=carried=out= at= micro=and=macrostructural= levels= in=order= to=acquire= the=mechanical=behaviour= of= constituent= materials= as= well= as= that= of= the= structural= elements= EpanelsFK= qhe=goal=of= the=experiments=is=to=acquire=a=basic=knowledge=of=the=mechanical=properties=of=different=earthen=materialsK==PK bumbofMbkTAi=moldoAM=

=PKNK Materials==

Table=N=ppecimens’=constituent=materials==

Type=of=application=

Material= ppecifications= Mass=density=ρ=[kgLmPz=

jasonry=panel= barth=block=

polid=blocks=produced=by=a=mechaniòed=hand=moulding=procedure=Eno=compressionI=plastic=consistencyF;=siòe=EOQM=x=NNR=x=TOF=mm=

NUSP= NUTM=

barthen=mortar=

phrinkage=O=BI=particle=siòe=up=to=Q=mmK=pand=particle= NUUR=

oammed=earth=panel=

oammed=earth=

phrinkage=MKR=BI=particle=siòe=range=MJNS=mmI=panels=produced=with=soil=moist=material=

ONVM=

`ob=panel= `ob= barthI=water=and=straw=fibres=of=OMM=to=PMM=mm=in=length= NQTR=

=

UQP=

barthen=materials=for=the=experiments=are=sourced=from=a=local=manufacturer=of=prefabricated=earthen=building=productsK=jaterial= specificationsI= mineralogy=and=granulometric=properties= for= the=different=wall=construction=typologies=are=listed=in=qabsK=NI=O=and=PK=qhough=certain=material=properties=are=specified=by=the=manufacturerI=detailed=parameters=required=for=the=structural=characterisation=of= the=constituent=materials=were=determined= in=the=BAj=laboratoriesK=barth= blocksI= earth= mortar= and= rammed= earth= are= readymade=products= from= the= manufacturerK= `obI=howeverI= was= prepared=at= the= BAj= premises= with= soil= from= the= manufacturer= of= the= other= earthen=products=and=straw=fibres=mixed=to=a=mass=of=plastic=consistencyK=jixing=was=performed=in=a=concrete=mixerK=After=mixingI=ETMM=×=TMM=×=NMMMF=mm=high=panels=were=built=following=traditional=cob=building=practiceK=After=drying=of=the=small=wallsI=the=test=specimens=were=cut=out=by=means=of=a=sawK==

Table=O=jineralogy=properties=of=earthen=materialsK=nuantitiesW=HHH=Z=highI=HH=Z=mediumI=H=Z=low==

Material= drain=constituents= Clay=fraction=

nua

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celd

spar

=

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=

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omite

=

Clin

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=

barthen=block= HHH= H= H= J= J= = HHH= HH= HH= J=

barthen=mortar= HHH= H= H= J= H= = H= HH= HHH= HH=

oammed=earth= HH= H= H= HHH= J= = H= HH= HHH= H=

`ob= HHH= H= J= J= J= HH= = HHH= HH= ==

Table=P=dranulometric=properties=of=the=used=earthen=materials=EmassJBF==

Material= dravel=and=pand=[=MKMSP=mm= pilt===MKMMOJMKMSP=mm= Clay=Y=MKMMO=mm=

barthen=block= QP= QR= NO=

barthen=mortar= RR= PT= NQ=

oammed=earth= SQ= OR= NN=

`ob= NU= SN= ON=

=PKOK Manufacturing=process=cor=the=static=compressive=experimentsI=wall=segments=of=siòe=RMM==×=ROM=×=NNM=mm=were=produced=made=of=S=earthen=unit=coursesI=in=accordance=with=bk=NMROJNW=NVVU=xVzK=eoweverI=the=courses=were=connected=by=OM=to=OR=mm=jointsI=and=thus=thicker=than=recommended=by=the=standardI=since=large=joint=widths=are=often=observed=in=historic=earth=block=masonryK=barth=block=masonry=specimens=were=built=without= preJwetting= the= earth=blocks= for= compression= testsK= cor= the= shear= tests= specimen= with= nonJwetted=as =well =as =wetted=blocks=were=builtK =jonolithic =panels =were=built =in =the=same=siòeK =oammed=earth=walls=were=produced=with=formworkI=whereas=cob=wall=segments=were=cut=from=bulk=specimenI=which=are=built=in=typical=cob=style=with=raw=earthI=water=and=straw=fibres=EOMM=to=PMM=mm=longFK=After=dryingI=segments=of=QOM=×=QOM=×=NNR=mm=in=siòe=were=cut=from=the=bulk=specimensI=thus=preserving=the=original=texture=of=the=cobK=After=productionI=the=panels=were=stored=in=a=climate=room=at=OP°`=and=RM=B=oe=with= the=aim=of=equilibrating=the=moisture=content= of= the=wallsK=ppecimens= were=removed=from=the=climate=room=shortly=before=the=strength=testing=took=placeK===QK ClMmobppflk=TbpT==QKNK Test=setup==`ompression=tests=were=performed=using=a=universal=testing=machineK=mrior=to=the=testsI=two=fJgirders=were=attached=to=the=lower=and=upper=side=of=the=wall=segments=in=order=to=introduce=the=compression=forces=into=the=specimensK=Accurate=parallelisation=of=the=girders=was=achieved=by=using=a=low=strength=cement=mortar=joint=between=the=girders=and=the=wall=segmentK=qests=were=performed=with=the=levelled=specimensI=where=the=smaller=sides=of=the=wall=segments=were=parallel=to=the=chosen=loading=plates=of=the=testing=machineK=cor=each=wall=typeI=Q=to=R=specimens=were=testedK=`ompressive=tests=were=carried=

=

UQQ=

out= under= displacement= controlK= qhe= loading= speed= was=adjusted= in=a= way= that= the= failure=point= was=reached=after=OM=to=PM=minutesK=aeformations=were=monitored=by=isaqs=parallel=and=perpendicular=to=the=loading=direction=on=both=sides=of=the=panel=specimenK=

=QKOK Test=results==qhe =setup =and =the =results =of =the =tests =are =shown =in =cigK =NK =cor =earth =block =masonry =wall =panels =the =strength=values=ranged=between=OKU=and=PKR=jmaK=qhe=displacement=was=in=the=range=MKR=to=NB=with=usually=an=abrupt=failureK=cailure=patterns=of= the=panels=are=depicted= in=cigK=NI= failure=was=visible=by=vertical=or=diagonal=cracksK=pometimes=cone=shaped=failure=pattern=could=be=observedK=oammed=earth=panels=reached=the=highest=compressive=strength=of=all= three=types=of=earth=constructionsK=qhe=values=ranged=between=PKQ=and=Q=jmaK=qhe=deformations=of=the=panels=were=similar=to=those=of=earth=block=masonryK=cailure=was=abrupt=after=maximum=stress=was=reachedK==

=========== ========== ==

cigK=N=barth=block=masonryI=rammed=earth=and=cob=specimens=under=compressionK=bxamples=of=failure=modes=Ecracks=marked=in=yellow=linesF=

=qhe=failure=pattern=showed=cone=shaped=cracking=patternI=at=least=one=sideI=sometimes=on=both=sidesK=`ob=showed=a=completely=different=behaviour=under=compressive=load=than=the=other=two=construction=typesK=jaximum=strength=ranged=from=NKQ=to=NKT=jmaK=aeformations=measured=were=high=reaching=up=to=S=B= of=vertical= strain= xNMzK=aue= to= the= content= of= straw= the= material= showed=a=ductile=behaviour=under= compressive= load= with= no= distinctive= maximum= yielding= pointK= `rack= patterns= after= the= tests=were=almost=randomly=and=only=in=one=sample=a=cone=shaped=failure=was=indicatedK=

=QKPK bvaluation=and=comparison=of=results=oesults= obtained= from= the= compression= tests= are= given= qabK= QI= where= bNLP= is= voung’s= modulus=measured =at =NLP =maximum =loadI =as =well =as =for =the =vertical =EnormalF =strain =εNLPK= qhe= stressJstrain=envelope=for=earth=block=masonry=shown=in=cigK=O=exhibits=a=short=phase=of=postJpeak=strain=softening=under=compressionI=due=to=its=brittle=behaviour=under=monoaxial=loadK=oammed=earth=shows=a=brittle===

Table=Q=oesults=from=compressive=strength=tests=End=Z=not=determinedF==

= Compressive=strength=[Mmaz=

Tensile=strength=[Mmaz=

voung’s=modulus=bNLP=[Mmaz=

sertical=strain=εNLP=[Bz=

moisson=ratio=[–z=

Mean= pTa= Mean= pTa= Mean= pTa= Mean= pTa= Mean= pTa=

barth=block= RKNM= MKPN= MKRM= MKNQ= ONVT= TN= MKMTN= MKMMO= MKQP= MKMT=

jortar= PKNS= MKQQ= MKPM= MKMU= NMST= NVN= MKRMM= MKMNM= nd= nd=

barth=block=masonry= PKOU= MKQM= nd= nd= UMP= OMQ= MKNQR= MKMQR= MKPT= MKNP=

oammed=earth= PKTP= MKOP= nd= nd= QNQP= VSN= MKMPN= MKMMT= MKOT= MKMQ=

`ob= NKRV= MKMP= MKPO= MKMS= SRN= QQN= MKNOP= MKMUP= MKNR= MKMQ=

=behaviourI=in=some=Ebut=not=all=and=not=markedlyF=cases=with=a=hardening=phase=present=in=the=first=part=of= the= stressJstrain= envelopeK= qhe= compressive= stressJstrain= envelope= of= cob= shows= its= deformation=beyond=the=elastic=range=with=a=gradual=drop=in=capacityI=presenting=a=ductile=behaviour=after=its=elastic=

=

UQR=

limitK=qhe=distinctive=maximum=strain=could=visible=be=observed=before=and=after=the=testK=qhere=was=a=strict=dependency=between=the=components=and=the=observed=material=behaviourK=fn=this=context=it=is=interesting= to= make= a= comparison= with= results= obtained= by= nuagliarini= et= alK= xRzI= who= studied= the=compressive=failure=behaviour=of=adobe=blocks=which=differed=constituentsK=qheir= results=showed=that=the=addition= of= straw= increased= the= ductility= of= the= material= considerablyI= while= the= introduction= of=sandI= particularly= in= high= amountsI= tended= to= significantly= lower= its= compressive= strengthK= qhis=difference= in= behavioural= pattern= was= similar= to= that= observed= for= the= different= earthen= materials=investigatedI= thus= giving=an= indication= of= the= effect= of=constitutive= materials= on= compressive=stressJstrain=behaviour=of=materials=resulting=from=different=construction=techniquesK=

=

==

cigK=O=`omparison=between=the=three=earthen=materials=under=compressionI=stressJstrain=envelope=

=RK afAdlkAi=ClMmobppflk=TbpT==RKNK Test=setup==aiagonal= compression= tests= were= performed= in= compression= mode= following= Apqj=b=RNVJNM= xNNzK=According=to=the=testI=to=induce=shear=forces=wall=segments=were=turned=by=QR°=around=the=middle=axis=with=one=diagonal=of=the=wall=segment=being=perpendicular=to=the=loading=plates=of=the=testing=machineK=qhe =stress =was =introduced =by =loading =shoesK =marticular =attention =was =directed =to =the =problem=of =the =load= distribution= along= the= corners= in= order= to= avoid= an= excessive= concentration= of= compression=stresses= at= these=surfacesK= qhe= loading=shoesI= placed=between= the= jack=and=the=cornerI= was= designed=according=to=the=standard=and=failure=of=the=panels=never=occurred=due=to=excessive=compression=stress=at= the= cornersK= pix= to= eight= specimens= were= tested= for= each= wall= construction= typeK= qhe= load= was=applied=at=a=rate=of=NPM=kLsK=qhe=test=consisted=in=monotonic=loading=up=to=failureK=aisplacement= transducers= were=used= for= measuring= strain=and=placed= according= to= the= standardI= one=pair= on= the= front= and= one= pair= on= the= back= side= of= the= panelK= cor= selected= specimen= additionally=a=photogrammetric=camera=system=EAoAjfpF=was=measuring=the=twoJdimensional=deformation=during=the=testK=cor=this=a=frame=of=caK=PR=×=OR=cm=of=the=center=of=the=panel=was=observedK=mrior=to=the=test=the=specimen=were=plastered=with=a=thin=white=earthen=render=and=sprayed=with=a=markerK=qhe=deformation=of= the= samples= was= measured= by= stereographic= recording= of= the= movement= of= the= singular= marker=points=and=additionally=by=one=set=of=isaqs=placed=on=the=back=side=of=the=panelK=qhe= test= is= usually= used= for= block= masonry= but= was= used= in= this= study= for= the= pseudo= monolithic=building=elements= rammed=earth=and=cobK= fn=monolithic=materials= the=diagonal= test=should= introduce=compression=forces=until=horiòontal=strain=creates=a=vertical=crackK=As=could=be=seen=in=the=resultsI=this=is=true=for=the=beginning=of=the=failureK=qhe=actual=failureI=howeverI=revealed=for=all=earthen=materials=a=strong=shear=componentK=

=RKOK Test=results=As=mentioned=before=masonry=panels=were=prepared=with=wetted=and=with=nonJwetted=blocksK=mast=and=current=practice= is=actually=not= to=wet= earth=blocks=for=buildingJup=earthen=masonryK=eoweverI= earth=blocks= show= generally= high= water= absorption= and= suck= out= moisture= from= the= fresh= mortarI= which=influences=the=bond=between=the=two=wall=components=greatlyK=qhis=naturally=has=also=a=big=influence=on= the= shear= strength= of= the= masonryK= As= a= comparisonI= therefore= O= sets= of= sample= panels= were=preparedI=one=set=with=nonJwetted=and=another=set=with=wetted=blocksK=jasonry= panels= with= nonJwetted= blocks= showed= very= low= shear= strength= valuesI= which= were= in= the=range=of=MKMU=and=MKNN=jmaK=qhe=stress=strain=curves=usually=showed=one=or=several=yielding=points=

=

UQS=

where=the=blocks=began=to=slide=gradually=and=until=friction=set=in=and=increased=stress=again=until=final=failureK=jasonry=panels=with=wetted=blocks=showed=much=higher=shear=strength=values=than=with=nonJwetted=blocksK=cor=the=three=tests=strength=values=MKOR=and=MKQ=jma=were=reachedI=which=is=two=to=three=times= higher= than= in= the= case= of= nonJwetted= blocksK= qhe= stressJstrain= curve= of= two= of= the= three=specimens=showed=a=distinctive=yielding=pointI=when=elasticity=of=the=samples=was=exceeded=and=first=cracks=appearedK=ptress=was=then=increasing=until=the=sample=failedK=qhe=maximum=deformation=values=were=approximately=the=same=for=both=sets=of=panelsK=qhis=type=of=stressJstrain=response=can=be=linked=to=the=actual=failure=mode=of=the=specimenK=qhe=sample=specimen=yields=the=stress=until=a=first=vertical=crack=appears=by=exceeding=the=maximum=elastic=horiòontal=strainK=qhe=crack=ran=not=only=along=joints=but=also=through=blocksK=At=the=second=yielding=point=the=sample=failed=by=sliding=of=the=blocks=along=the=joints=until=complete=collapseK=qhis=failure=pattern=could=also=be=observed=on=rammed=earth=panels=EcigK= PFK= oammed= earth= panels= yielded= the= highest= results= for= shear= strength= of= all= three= different=construction=typesK=salues=ranged=between=MKSR=and=MKUR=jmaK=qhe=maximum=strain=was=much=higher=than=with=earth=block=masonry=and=usually=between=N=and=OB=before=complete=failureK=

=

==== ==== ==

cigK=P=barth=block=masonryI=rammed=earth=and=cob=specimens=under=diagonal=compression==Almost=all=the=panel=specimen=safe=for=one=showed=a=distinctive=yielding=point=after=the=elastic=range=on=the=stressJstrain=curvesK=lbservation=from=video=footage=showed=the=development=of=failureW=

– ko=visible=changes=in=the=elastic=range=of=the=strain;=– Appearance=of=a=vertical=crack=close=to=the=first=yielding=point;=– aevelopment=of=a=system=of=small=parallel=running=vertical=cracks=with=an=increase=in=load;=the=

systems=usually= run=diagonal= from=one= end= of= the=upper= loading= shoe= to= the= other= end=of= the=lower=one;=

– `ombination= of= the= single= shear= cracks= to= one= coherent= crack= running= diagonally= through= the=sample= at= the= maximum= load;= sometimes= the= diagonal= shear= crack= run= partially= through= the=vertical=crack;=

– `ollapse=of=the=sampleK=

0

10

20

30

40

50

60

0,0 0,5 1,0 1,5 2,0

ioad

[kk

]

Shear strain [%]

N

N

2

2 3 4

3

4

==

cigK =Q=oesults= from=photogrammetric=analysis=by=AoAjfp=and= the=corresponding=stressJstrain=curve=showing=the=deformation=of=two=rammed=earth=panelsK=vellowI=red=and=white=colours=indicate=crackingK=kote=the=diagonal=======================deformation=in=the=elastic=range=which=is=parallel=to=the=rammed=earth=layers=

=

UQT=

ft=is=noteworthy=that=even=though=a=first=vertical=crack=appeared=in=the=panels=an=increase=in=load=was=still=possibleK=kot=in=every=sample=the=vertical=crack=was=combined=with=the=diagonal=crack=systemK=fn=two=of=the=seven=samples=tested=both=cracks=appeared=to=be=independentK=ft=is=probably=safe=to=say=that=the= final= failure= was= not= caused= by= compression= but= mostly= by= shear= failure= as= in= the= earth= block=masonry=wall=panelsK=qhe=photogrammetric=analysis=by=the=AoAjfp=Pa=system=essentially=confirmed=the= findings= from= the= stressJstrain= curves= and= the= analysis= of= the= failure= modeK= cigK= Q= shows=exemplarily=the=results=of=one=of=the=rammed=earth=panels=testedK==qhough=only=a=section=of=the=entire=panel=was=visualiòed=the=development=of=cracks=on=the=stressJstrain=curve= followed= the= scheme= as= described= aboveK= fnteresting= was= the= appearance= of= a= diagonal=deformation =Ein =cigK =Q =indicated =by =red =linesF =in =the =elastic =range =of =the =curveK =qhe =direction =of =the =deformation=was=in=the=layering=of=the=rammed=earthK=pome=of=these=deformations=became=cracks=by=increasing=the=load=to=the=maximum=valueK=bven=though=cob=wall=panels=EcigK=RF=revealed=the=lowest=strength= values= in= the= compression= testsI= the= results= from= the= diagonal= compression= EshearF=experiments=where=much=better=than=that=of=the=earth=block=masonry=panels=and=only=slightly=below=the=values =for =rammed =earth =panelsK =qhe =strength =figures =ranged =from =MKQM =to =MKSR =jma =EcigK =SFK =qhe =maximum=strain=wasI=as=in=the=compression=testsI=the=highest=of=the=three=earth=construction=techniques=ranging=from=O=to=RBK===

0

5

10

15

20

25

0,0 0,5 1,0 1,5 2,0 2,5 3,0

ioad

[kk]

Shear strain [%]

16 and 78

N

N

23 4

2 3 4

==

cigK=R=oesults=from=the=photogrammetric=analysis=EAoAjfpF=and=the=corresponding=loadJstrain=curve=showing=the=deformation=of=two=cob=panelsK=vellowI=red=and=white=colors=indicate=cracking=

=A=first=yielding=point=on=the=stressJstrain=curveI=as=observed=for=the=masonry=and=rammed=earth=panels=could=not=be=recognised=on=the=curves=of=the=cob=specimen=EcigK=RFK=qhe=typical=course=was=an=elastic=range =with =a =low =shear =modulus =followed =by =a =plasticJtype =deformation =of =the =sample =specimenK =qypical=vertical=cracks=due=to=the=compression=load=as=observed=with=the=other=two=construction=types=were= not= identifiable= hereK= rsually= the= specimens= collapsed= after= reaching= maximum= load=by= shear=failureK=`racks=were=always=running=diagonally=from=one=end=of= the=upper= loading=shoe=to=the=other=end=of=the=lower=shoe=EcigK=PFK=qhe=results=by=AoAjfp=showed=that=majority=of=the=cracking=occurred=not= in= the= end= of= the= elastic= range= but= on= the= way= to= the= plateau= of= the= maximum= load= EcigK= RFK=eoweverI= when= the= maximum= load= was= reached= cracking= was= prominent= and= failure= followed=suitI=even=though=deformation=was=still=possible=since=the=specimen=parts=were=still=held=together=by=strings=of=straw=fibreK===RKPK bvaluation=and=comparison=of=results=oesults=obtained=for=diagonal=compression=tests=and=calculated=according=to=Apqj=bRNVJNM=xNNz=are=given=below=in=qabK=RI=where=dNLP=is=the=shear=modulus=of=elasticity=measured=at=NLP=maximum=loadI=as=well=as=for=the=shear=strain=γNLPK=qhe=maximum=shear=strength=of=the=specimens=was=calculated=from=the=maximum=loadK=cigK=S=shows=a=comparison=of= the=behaviour=between=earth=block=masonryI= rammed=earth= and= cob= in= terms= of= results= for= diagonal= compression= loadsK= As= in= the= case= under= vertical=compressionI= cob= presented= a= marked= and= significant= postJpeak= strain= phase= before= failureI= with=a=gradual= drop= in= capacityK= oammed= earthI= as= in= compressive= testI= shows= a= hardening= phase= at= the=

=

UQU=

beginning= with= failure= starting= from= compaction= planesK= ft= is= important= to= remark= that= earth= block=masonry= samplesI= which= were= manufactured= without= wetting= the= earth= blocks= showed= insufficient=bonding= between= mortar= and= blocksK= qhis= might= have= caused= micro= damages= when= handling= and=preparing=the=specimen=for=the=testK=qhis=also=had=certainly=a=strong=influence=in=the=low=shear=strength=values=exhibited=by=the=masonry=specimenK==

Table=R=oesults=from=diagonal=compression=tests=in=comparison=Et=Z=earth=blockI=wetted;==pqa=Z=standard=deviationF=

=

= phear=strength=τu=[Mmaz= phear=modulus=d=NLP=[Mmaz= phear=strain=γNLP=[Bz=

Mean= pTa= Mean= pTa= Mean= pTa=

barth=block=masonry= MKMV= MKMN= QN= R= MKMTQ= MKMNT=

barth=block=masonry=EtF= MKPQ= MKMS= SSM= OTT= MKMOM= MKMNN=

oammed=earth= MKTN= MKNN= OPOS= TNM= MKMNN= MKMMP=

`ob= MKRM= MKNM= QOM= NPT= MKMQN= MKMMS=

=

==

cigK=S=`omparison=between=earth=block=masonryI=rammed=earth=and=cob=under=diagonal=compressionI=envelope=of=stressJstrain=curvesK=kote=the=difference=in=results=with=earth=block=masonryI=when=wetted=and=dry=blocks=were=used=

=SK ClkCirpflkp==qhis= part= presents= an= analysis= of= the= mechanical= properties= of= traditional= earthen= construction=materialsI=based=on=results=obtained=from=compressive=and=shears=testsK=Basic=parameters=concerning=seismic=behaviour=were=determinedI=including=shear=strengthI=shear=modulus=and=elastic=modulusK=qhe=compressive=tests=on=wall=panels=were=carried=out=with=displacement=controlI=and=it=was=thus=possible=to= determine= post= peak= strain= performanceK= aiagonal= compression= test= were= performed= under= force=controlK= fn= terms= of= compressive= strengthI= the= maximum= value= of= PKTP= jma= was= obtained= for= the=rammed=earth=specimensI=whereas=the=compressive=strength=of=earth=block=masonry=and=cob=was=found=to=be=UUB=and=QPBI=respectivelyI=of=that=of=rammed=earthK==fn= the= second= part= of= the= research=programI= diagonal= compression= testing= was= carried= outI= yielding=a=maximum= shear= strength= value= of= MKTN= jma= for= the= rammed= earth= specimensI= MKRM= for= cob= and=a=significantly= lower= value= for= earth= block= masonryK= cor= earth= block= masonry= the= construction=technique=is=essential=for=performanceK=tith=the=same=materials=but=with=dry=and=wetted=earth=blocks=prior= to= laying= the= wall= panels= yielded= different= results= in= the= shear= tests= EqabK= RFK= joistening= the=blocks=prevents=early=water=reduction=in=the=mortarI=thus=improving=the=bond=between=mortar=and=earth=block =and =enabling =the =increase =of =the =shear =strength =of =a =masonry =wall =two =to =three =timesK =ln =the =other=handI=for=historical=buildings=the=masonry=often=shows=a=poor=bond=between=block=and=mortarI=indicating= that= blocks= were= not= wetted= and= therefore= a= low= value= for= shear= strength= has= to= be=anticipatedK==A=general=conclusion=which=can=be=drawn= is= that=cobI=which=exhibits= lower= compressive=resistanceI=shows= relatively=ductile=post=peak=behaviour= when=compared=with= the=brittle=behaviour= of= the= earth=block=masonry=and=rammed=earth=specimensW=cob=can=deform=beyond=the=elastic=range=with=a=gradual=drop= in= capacityK= qhis= behaviour= is= strongly= influenced= by= the= presence= of= fibresK= aespite= its= low=compressive= strengthI= cob= thus= presents= a= relatively= good= performance= within= the= earthen= material=

=

UQV=

range=as=far=as=shear=behaviour=is=concernedK=qhis=parameterI=together=with=its=long=post=peak=plastic=phaseI=is=relevant=if=its=utilisation=in=seismic=areas=is=consideredK=Buildings=in=these=areas=are=bound=to=be= subjected= to= lateral= displacements= and= the= ability= of= a= building= to= deform= without= collapsing= is=essential=for=saving=human=lives=and=the=repair=of=a=structureK==AChkltibadMbkTp==qhis=research=was=funded=by=the=buropean=`ommission=under=contract=koK=OQQNOPK===obcbobkCbp==xNz sargas= gKI= Bariola= gKI= Blondet= jKI= jehtaI= mKhK= ENVUSF= peismic= strength= of= adobe= masonryK=

jaterials and ptructures=NVEQFW=ORPJORUK=xOz Apqj=bOPVO=L=bOPVP=j=EOMNMF=ptandard guide for design of earthen wall building systems=xPz fpNPUOT= ENVVPF= fndian standard guidelines for improving earthquake resistance of earthen

buildingsK=xQz kqb=bKMUM=Adobe=EOMMMF=qechnical Building ptandardI meruK=xRz nuagliarini= bKI= ienci= pK= EOMNMF= qhe= influence= of= natural= stabiliòers= and= natural= fibres= on= the=

mechanical=properties=of=ancient=ooman=adobe=bricksK=gournal of Cultural eeritage=NNEPFW=PMVJPNQK=xSz qorrealva= aKI= sargas= keumann= gKI= Blondet= jK= EOMMVF= barthquake= resistant= design= criteria= and=

testing= of= adobe= buildings= at= montificia= rniversidad= `atòlica= del= meruK= fnW= mrocK of the detty seismic adobe project 2MMS colloquium=qhe=detty=`onservation=fnstituteI=PJNMK=

xTz pchröder= eK= EOMNMF= iehmbau J jit iehm ökologisch planen und bauenK= siewegHqeubnerI=tiesbadenK=

xUz gaquin =mKAKI =Augarde =`KbKI =derrard =`KjK =EOMMTF =eistoric =rammed =earth =structures =in =ppainW =construction=techniques=and=a=preliminary=classificationK=fnW=senkatarama=oeddy=BK=sKI=jani=jK=EedsF= mrocK of fnternational pymposium on barthen ptructures= BangaloreI= fndiaK= fnterline=mublishingK=

xVz bk=NMROJN=ENVVUF=jethods of tests for masonryK mart 1: aetermination of compressive strengthK=xNMz jiccoli=iKI=jüller=rKI=merrone=̀ KI=wiegert=`K=EOMNOF=barth=block=masonryI=rammed=earth=and=cobW=

earthen=components=from=different=construction=techniques=and=their= structural=performanceK= fnW=mrocK of ufth fnternational conference on the study and conservation of earthen architectural heritageI qerra 2M12=iimaI=meruI=April=OOndJOTthK=

xNNz Apqj= RNVJNM= EOMNMF= ptandard test method for diagonal tension Eshear) in masonry assemblagesK=American=pociety=for=qesting=and=jaterialsK=