OOVT

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

qeb alrBibJiAvboba cAÇAabp lc mAiAZZl arCAib IN sbNICbW obpriqp colM qbpqINd ANa ilNdJqboM MlNIqloINd diçsuè BçscatçN, palvatçre oussçO, crancesca pciarrettaP ABpqoACq qhe rese~rch h~s st~rted frçm ~ lçngJterm mçnitçring ~ctivity in prçgress çn the twç extern~l jediev~l f~ç~des çf m~l~zzç auc~le in seniceI ft~ly. qhe currently ~v~il~ble infçrm~tiçn ~bçut the cçnstructiçn çf this wçrldwide f~mçus mçnument is surprisingly sc~rce. qhe f~ç~des under mçnitçring ~re cçmpçsed by ~n intern~l l~yer çf lç~dJbe~ring brick m~sçnry ~nd ~n extern~l cl~dding çf pçlychrçme stçnes. qhe m~in çbjectives çf the whçle mçnitçring prçgr~mme cçncern the imprçvement çf knçwledge ~bçut the cçnstructiçnI mech~nic~l fe~tures ~nd çver~ll st~tic ~nd dyn~mic beh~viçur çf the f~ç~des. fn det~ilI the p~per repçrts the respçnse ~n~lysis çf ~ structur~l sectiçn tç envirçnmentJinduced dyn~mic ~ctiçnsI çn the grçunds çf the d~t~ cçllected by the dyn~mic mçnitçring system. All the d~t~ ~nd perfçrmed c~lcul~tiçns h~ve been useful tç est~blish the service cçnditiçns çf the structure ~nd tç set up ~ prelimin~ry cb mçdel. si~ spectr~l respçnse ~n~lysisI the tr~nsl~tiçn~l çutJçfJpl~ne stiffness çf the w~llJtçJflççr ~nd w~llJtçJ rççf cçnnectiçns w~s ~ssessedX ~s wellI the influence çf m~teri~l’s stiffness çn the cçrrespçndence çf numeric tç experiment~l results cçuld be ev~lu~ted. heywçrds: malazzç aucale senice, açuble-layered façade, ptatic and dynamic mçnitçring,

lutput-çnly technièue, aamping cçefficient NK INqolarCqIlN NKNK Investigation programme at malazzo aucale qhe p~per presents ~ unique c~se çf lçngJterm mçnitçring çn çne çf the mçst represent~tive ~nd v~lu~ble histçric buildings çf ft~lyI i.e. m~l~zzç auc~le in senice Ecigure NF. crçm lctçber OMNMI the oese~rch rnit çn p~fety Assessment çf jçnuments ~t the frAs rniversity çf senice is c~rrying çut ~ st~tic ~nd dyn~mic mçnitçring çf the twç extern~l mediev~l f~ç~des çf the building. qhese ~re dçubleJl~yered m~sçnry w~llsI cçnsisting çf ~n intern~l lç~dJbe~ring brick ~nd mçrt~r m~sçnry l~yer ~nd ~n extern~l cl~dding çf stçne blçcks ~nd very thin mçrt~r jçints. qhe fe~tures çf l~yers’ interlçcking cçuld nçt be cert~inly knçwn Ecigure OF. A multiJdisciplin~ry s~fety ~ssessment prçgr~mme w~s thus el~bçr~ted tç ev~lu~te the inner cçnsistency çf the w~llsI the current st~te çf preserv~tiçn ~nd pçssible critic~l zçnesI ~nd fin~lly tç set dçwn m~inten~nce guidelines. qhis prçgr~mme is still in prçgress until lctçber OMNOX it cçnsists çf the fçllçwing ph~sesW NF detectiçn ~nd ~n~lysis çf the p~st restçr~tiçn wçrksI OF geçmetric~l surveyI PF st~ticI dyn~mic ~nd envirçnment~l lçngJterm mçnitçringI 4F shçrtJterm mçnitçringI i.e. nçnJdestructive ~nd micrçJdestructive testingI RF geçtechnic~l testsI SF numeric mçdellingI TF physic~l mçdelling xNz. qhe dyn~mic mçnitçring Eph~se PF invçlves the sçuth f~ç~de çf m~l~zzç auc~le. ayn~mic sensçrs Ei.e. uniJ~xi~l ~ccelerçmetersF ~re ~ligned ~lçng çne vertic~l line çn the pçuth f~ç~deI tç cçntrçl the çutJçfJpl~ne respçnse çf ~ sectiçn çf the w~ll tç dyn~mic ~ctiçns. qhis sectiçn w~s chçsen tç be ~s clçse ~s pçssible tç the mçst cçncerning zçne çf the f~ç~deI i.e. ~ pçintedJ~rch windçw frçm which ~ piece çf vçussçir h~d f~llen. qhe three mçnçJ~xi~l ~ccelerçmeters ~re inst~lled ~t regul~r dist~nces N mh. a.I frAs rniversity çf seniceI gbçsc~tç]iu~v.it O mrçfessçrI frAs rniversity çf seniceI russç]iu~v.it P mh. a.I frAs rniversity çf seniceI scifr~]iu~v.it

OOVU

~t the tçpI middle ~nd bçttçm çf the w~ll Ethe bçttçm level cçrrespçnds tç the flççr çf the oççm çf j~ggiçr CçnsigliçFI th~t is ~bçut NO m high ~nd cçnstr~ined çnly ~t its tçp ~nd bçttçmI respectively tç the rççf ~nd tç the flççr çf the Ch~mber çf j~ggiçr Cçnsigliç. cigure P shçws the mçnitçred zçne ~nd the det~ils çf the three ~ccelerçmeters n~med AjNJPI th~t me~sure ~cceler~tiçn az ~lçng the z ~xis ~s indic~ted.

cigK N pçuth f~ç~de çf m~l~zzç auc~le ~nd mçnitçred zçne

cigK O oecçnstructiçn çf the intern~l structure çf the f~ç~de w~ll qhe whçle mçnitçring system h~s ~lre~dy been presented ~nd described elsewhere by the ~uthçrs xOz. qhe dyn~mic mçnitçring system is cçmpçsed çf P piezçJelectric uniJ~xi~l ~ccelerçmetersI h~ving ~ nçmin~l sensitivity çf NMMM msLg with ~ resçlutiçn çf –NRB Ebeing g the gr~vity ~cceler~tiçnFI within ~ frequency r~nge frçm M.MOR tç UMM ez Ewith ~ resçlutiçn çf the –RB çf the whçle r~ngeF. qhe me~surement r~nge çf the pe~k ~cceler~tiçn is –O4.R mLs². b~ch sensçr c~n h~ve its çwn trigger threshçld. qhe sign~l running frçm e~ch sensçr is digit~lized ~nd preJel~bçr~ted with eigh m~ss digit~l filter. qhe ~cquisitiçn system st~rts recçrding ~n event if the trigger cçnditiçn ~ctiv~tes within ~ definite time windçwI i.e. the threshçld v~lue is exceeded çn çne çr mçre ch~nnels. qhe system ~lsç c~lcul~tes ~nd recçrds the minimum ~nd m~ximum ~cceler~tiçns çn ~ preJdefined periçd çf çne d~yX this ~llçws tç knçw the extent çf dyn~mic stress even if it dçes nçt exceed the threshçld. qhe d~t~ c~n be checked in re~l time ~ndLçr dçwnlç~ded frçm remçteI by internet cçnnectiçn.

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cigK P aet~il çf the mçnitçred zçne ~nd inst~lled ~cceler~tiçn sensçrs

NKOK aynamic monitoring qhe first ~im çf the dyn~mic mçnitçring is tç cçntrçl the level çf dyn~mic stress ~s clçse ~s pçssible tç the zçne çf stçne f~ilure. auring the mçnitçringI the recçrded çutJçfJpl~ne ~cceler~tiçns h~ve ~llçwed tç re~lise the çrdin~ry level çf dyn~mic ~ctiçns th~t cçncern the investig~ted zçne çf the w~ll. qhese ~ctiçns c~n be ~scribed mçstly tç the building’s çccup~ncy ~s ~ museum Ei.e. tr~mpling çf visitçrsI vibr~tiçn tr~nsmitted frçm the clçsing çf entr~nce dççrsF. qhe effects çf çther types çf ~ctiçnsI th~t c~n be reg~rded ~s extr~çrdin~ry Ei.e. firewçrk shçws ~nd seismic ~ctiçnsF cçuld be detected ~s well xPz. OK bumboIMbNqAi obpriqp qhe ~n~lysis çf the f~ç~de w~s led within ljA Elper~tiçn~l jçd~l An~lysisF ~pprç~chI t~king intç cçnsider~tiçn the ~mbientJinduced excit~tiçn. qhe kind çf ~n~lysed sign~l is ste~dy E~mbient nçiseF ~s well ~s tr~nsient Eçrdin~ry ~nd extr~Jçrdin~ry eventF OKNK Ambient vibration qhe structur~l beh~viçur with reference tç the ~mbient nçise w~s ~n~lysed with ~ ste~dy sign~l recçrded the NMth çf April OMNO. cigures 4 ~nd R shçw the recçrdings in the time dçm~in ~nd the frequency dçm~in ~n~lysis perfçrmed with c~st cçurier qr~nsfçrm ~lgçrithm ~t e~ch cçntrçl pçint AjNJP. qhe ~cceler~tiçnJtime di~gr~ms – left cçlumn çf cigures 4 ~nd R – were el~bçr~ted thrçugh ~ p~ss b~nd cinite fmpulse oespçnse filterI with cutçff frequency çf M.OR ~nd PM ez. qhis h~s ~llçwed tç cle~r çff ~ll the interferencesI bçth in the lçw frequencies due tç b~ckgrçund nçiseI ~nd in the high frequencies due tç m~gnetic fields th~t cçuld influence the mçnitçring system. fn the left cçlumns çf cigures 4 ~nd RI the ~rrçws pçint the fund~ment~l frequencies çf N.ST ~nd N.T4 ez.

OPMM

cigK 4 ppectr~ in time ~nd frequency dçm~in

cigK R ppectr~ in time ~nd frequency dçm~in

OKOK lrÇinary event fn det~ilI events cçrrespçnding tç the museum’s dççr çpening ~nd clçsure h~ve been fçund tç recur d~ilyI ~nd tç determine the m~jçrity çf d~ily pe~k ~cceler~tiçns. q~ble N lists the relev~nt figures fçr e~ch cçnsidered mçnthI highlighting the recurrence çf the highest pe~k E~s ~bsçlute v~lueF in çr~nge ~nd highest me~n v~lue in yellçw.

qable N me~k ~nd ~ver~ge ~cceler~tiçns in ~ s~mple çf PM events

pensor AccK EgF

Nov OMNM

aec OMNM

gan OMNN

ceb OMNN

Mar OMNN

Apr OMNN

May OMNN

gun OMNN

gul OMNN

AjN pe~k M.MMSO M.MMRP M.MMR4 M.MMRV M.MM4U M.MM4O M.MMRM M.MM4P M.MMRS

~ver~ge M.MMPN M.MMO4 M.MMPR M.MMOP M.MMOO M.MMO4 M.MMOR M.MMOS M.MMOT

AjO pe~k M.MM4M M.MMRR M.MMR4 M.MM4M M.MMPV M.MMRV M.MM44 M.MMSR M.MMSS

~ver~ge M.MMOO M.MMO4 M.MMOM M.MMON M.MMOO M.MMOV M.MMOS M.MMPM M.MMOV

AjP pe~k M.MMPP M.MMRN M.MMSN M.MMRO M.MMRO M.MMRP M.MM4T M.MMRR M.MMTN

~ver~ge M.MMOO M.MMOO M.MMNV M.MMOP M.MMOR M.MMOS M.MMOT M.MMOU M.MMOU

OPMN

qhe dçmin~ting frequencies were individu~ted with the ~n~lysis çf the first mçd~l sh~pe in which ~ll pçints çf the system mçve sinusçid~lly with the s~me frequency ~nd with ~ fixed ph~se rel~tiçn. qhe frequency çf first three mçd~l sh~pes were individu~ted by the simult~neçus presence çf pe~ks in the eigenJspectr~ ~nd the cçsine çf the ph~se difference ~mçng three ch~nnels being ~pprçxim~tely equ~l tç JN Eph~se çppçsitiçnF çr N Ein ph~seF. cigure S shçws the mçd~l sh~pes çf çrdin~ry event.

cigK S jçd~l sh~pes çf çrdin~ry event

OKPK bxtraJorÇinary event qhe respçnse tç ~n extr~çrdin~ryJtype eventI i.e. ~n e~rthqu~keI h~s been me~sured during the mçnitçring periçd. qhe e~rthqu~ke h~ppened the NTth çf guly ErqC NUWPMWOUFI OMNNI h~d ~ m~gnitude çf 4.T ~nd its epicentre w~s lçc~ted in the m~inl~nd çf senetç regiçnI ft~ly. qhe mçd~l sh~pes were c~lcul~ted by cçrrel~tiçn çf results recçrded by every ~ccelerçmetric directiçn Ecigure TFI ~s expl~ined with the ~n~lysis çf çrdin~ry event.

cigK T jçd~l sh~pes çf extr~Jçrdin~ry event

PK cbM MlabiiINd PKNK mroceÇure anÇ assumeÇ properties aue tç the mçnitçring system cçnfigur~tiçnI the mçdel is limited tç the f~ç~de pçrtiçn th~t cçrrespçnds tç the Ch~mber çf j~ggiçr Cçnsigliç. qhe first çbjective çf the mçdel is tç identify the dyn~mic respçnse çf the f~ç~de tç free vibr~tiçns. qhe experiment~l d~t~ h~ve ~llçwed tç build ~ prelimin~ry Oa structur~l mçdel with ptr~ndT O.O.P finite element sçftw~re Ecigures PCJaF. qhe mçdel reprçduces the f~ç~de pçrtiçn with NUPM pl~tes cçrrespçnding tç the rççm çf j~ggiçr CçnsigliçI ~imed tç ~ssess the tr~nsl~tiçn~l stiffness çf w~llJtçJrççf ~nd w~llJtçJflççr cçnnectiçns in z directiçn. qhe m~teri~l çf f~ç~de element is mçdeled ~s çrthçtrçpic with the mech~nic~l ch~r~cteristics shçwn in q~ble O. fn the s~me t~ble ~re listed the glçb~l sizes çf f~ç~de.

OPMO

qable O mhysic~l ~nd mech~nic~l prçperties

mroperty salue bl~stic mçdulus – u directiçn EbuF RPO kLmm² bl~stic mçdulus – v directiçn EbvF ONRR kLmm² bl~stic mçdulus – w directiçn EbwF RPO kLmm²

mçissçn’s r~tiç – uv EnuvF M.N mçissçn’s r~tiç – vw EnvwF M.NN mçissçn’s r~tiç – wu EnwuF M.MS phe~r mçdulus – uv EduvF TU kLmm²

aensity NVMM kgLm³ iength RNPSM mm eeight NNVRM mm

qhickness VMM mm

pix cçnditiçns frçm zerç tç infinite stiffness in were ~ttributed tç the tçp ~nd bçttçm springs ~nd cçmbinedI le~ding tç PS c~ses in ~ll. qhe numeric d~t~I i.e. displ~cements ~nd ~cceler~tiçns ~lçng the z directiçnI ~re yielded by spectr~l respçnse ~n~lyses thrçugh ~ll the c~ses. qhe input spectrum w~s deduced experiment~lly frçm ~n çrdin~ry ~nd extr~Jçrdin~ry excit~tiçn cçrrespçnding tç the clçsure çf the juseum’s dççr rispectivelyX the numeric results were cçmp~red tç the cçrrespçnding çutJçfJpl~ne displ~cements ~nd ~cceler~tiçns frçm ccq ~n~lysis. qhis ~pprç~ch ~lsç le~ds tç ev~lu~tiçn a pçsteriçri çf the frequencies çf the structureI th~t in f~ct c~n be ev~lu~ted çnce the m~tching between numeric ~nd experiment~l d~t~ ~llçw tç est~blish bçund~ry cçnditiçns. qhe results h~ve shçwn th~t numericJexperiment~l cçrrespçndence cle~rly imprçves ~t incre~sing v~lues çf stiffness çf bçth the lines çf springsI ~nd this c~n likely be the prççf çf ~ high tr~nsl~tiçn~l stiffness çf the cçnnectiçns in the ~ctu~l structure.

cigK U ayn~mic mçnitçring çf m~l~zzç auc~le in senice EA – wçne under cçntrçlI aet~il çf the ~ccelerçmetersI pt~tic scheme çf the mçnitçred sectiçnI B – Axçnçmetric view çf the cb mçdelF

cigure V shçws the first result çf dyn~mic respçnse çf f~ç~de in free vibr~tiçn fieldI the fund~ment~l frequency is N.4Tez.

cigK V cirst mçde çf vibr~tiçnI fund~ment~l frequency N.4Tez. cb mçdel

OPMP

4K NrMboIC ANAivpIp qhe numeric ~n~lysis ~ccçunts fçr the w~ll ~s ~ pl~ne sl~b with cçnst~nt thickness. qhe differenti~l equ~tiçn çf vibr~tiçn~l mçtiçn is the fçllçwing Ebq. NF

O

O

4

4

OO

4

4

4

OtB

myyxx ¶

¶×-=

¶¶

+¶¶

¶+

¶¶ zzzz

ENF

~nd ~ssuming the rel~tiçnship in bq. EOF

tsenyx wzz FIE= EOF the defçrmed sh~pe ζEx,yFI bq. EPF c~n be yielded frçm bq. ENF

zzzzz 4

4

4

OO

4

4

44 O k

yyxx=

¶¶

+¶¶

¶+

¶¶

=Ñ EPF

where

Bmk

O4 w=

EP~F

with

( )O

P

P.MNNO -×

=sbB z

Accçunting fçr ~ pinned bçund~ry ~nd the slenderness in bçth directiçnsI the sçlutiçn çf bq. EPF c~n be expressed with the fçllçwing bq. E4F

bynsen

axmsen`yx ppz ××=FIE

E4F

~nd substituting bq. E4F in bq. EPFI the rel~tiçnship in bq. ERF c~n be çbt~ined

4

O

O

O

O

O4 k

bn

am

=÷÷ø

öççè

æ+p

ERF

hence

mB

bn

am

O

O

O

O

O4O

÷÷ø

öççè

æ+= pw

ESF

thus the fund~ment~l frequency c~n be determined with bq. ETF

sgB

bn

amf

××

÷÷ø

öççè

æ+=

gp

O

O

O

O

M O ETF

Cçnsidering the relev~nt mçde sh~pes Ei.e. ~lçng the çutJçfJpl~ne directiçnFI the el~stic mçdulus ~ssumed in the ~n~lysis is bzI see q~ble O.

OPM4

RK ClNCirpIlNp qhe first ~n~lyses çn the dyn~mic respçnse çf the f~ç~de çf m~l~zzç auc~le h~ve led tç the fçllçwing cçnclusiçnsW - the st~tic ~nd dyn~mic mçnitçring representsI currentlyI the çnly effective methçd fçr cçntrçlI

~ssessment çf d~m~ge ~nd structur~l identific~tiçn çf mçnuments ~nd histçric~l buildings. qhe ~n~lysis çf the structur~l respçnse tç ~mbient vibr~tiçnsI with st~tiçn~ry sign~l ~nd with tr~nsientI ~llçws the deepening çf knçwledge çf the building’s st~teI under service~bility cçnditiçns çr pçstJdis~ster st~teI thrçugh nçnJintrusive ~pprç~ch. qhe c~libr~tiçn çf the numeric~l mçdel thrçugh the experiment~l resultsI fçllçwing mçdel upd~ting prçceduresI is the suppçrt tççl fçr design çf structur~l reh~bilit~tiçnX

- the mçdel upd~ting prçcedureI thrçugh experiment~l v~lues çbt~ined by dyn~mic ~nd st~tic mçnitçring in lçng timeI gu~r~ntees the mçdel’s c~libr~tiçn th~t simul~tes the ~ctu~l structur~l cçnditiçn çf buildingsX

- the prçpçsed ~pprç~ches tç ev~lu~tiçnI i.e. experiment~l d~t~I cb mçdelling ~nd numeric ~n~lysis fçllçwing the pl~ne sl~b hypçthesisI pçint çut ~ gççd cçrrel~tiçn Eq~ble PF. qhe cçmp~risçn çf experiment~l d~t~ tç results çf cbj ~nd çf numeric ~n~lysis pçints çut respectively ~ difference çf NNB ~nd RB. tith reference tç the frequency çf the first vibr~tiçn mçdeI the effect çf çpenings ~ccçunted fçr in the cb mçdel Eth~t is N4B circ~ çf the whçle f~ç~deF c~n be neglectedI if cçmp~red tç the slenderness çf the w~ll.

- st~rting frçm the dyn~mic respçnse ~n~lysis ~bçve presentedI the next gç~l will be the ~ssessment çf the invçlved bçund~ry cçnditiçns ~nd the mech~nic~l ch~r~cteriz~tiçn çf the cçmpçnent m~teri~ls çf the f~ç~deI in çrder tç c~libr~te the interpret~tive mçdel çf such ~ cçmplex f~ç~de system ~s ~ccur~tely ~s pçssible.

qable P cund~ment~l frequencyI experiment~l EbumF resultI finite element EcbjF

~nd numeric~l Eby bq. TF ~n~lysis

bum cbM NumericalI bq ETF ~N.ST ez N.4T ez N.RU ez

ACKNltibadbMbNqp qhe ~uthçrs w~rmly th~nk Arch. a. Andreçzzi ~nd Arch. A. Abb~te ~t jrsb Eqçwn juseums çf senice cçund~tiçnFI ~s well ~s jr fv~nç AldreghettiI jr di~cçmç BusettçI jr j~riç CelebrinI jr diçrgiç Cçst~ntiniI jr içrenzç j~ss~ri~I jr sincenzç pc~furi ~nd jr ft~lç qçf~ni fçr their preciçus wçrk. obcbobNCbp xNz AndreçzziI a.I B~rbieriI A.I Bçsc~tçI d.I aei pv~ldiI A.I duerr~I c.I ai qçmm~sçI A.I i~zz~riniI

i.I jir~bell~ oçbertiI d.I merçnI c.I oiv~I d.I oussçI p.I pc~ppinI i.I pci~rrett~I c.I w~nI B. EOMMVF. fntegr~ted cçntrçl in mçnitçring histçric buildingsX the c~se çf w~ll structures çf m~l~zzç auc~le in seniceI mrçceedings çf mrçeiqech MV – fntern~tiçn~l Cçnference çn mrçtectiçn çf eistçric~l BuildingsI oçme ONJO4 gune OMMV.

xOz Bçsc~tçI d.I oiv~I d.I oussçI p.I ~nd pci~rrett~I cI EOMNNF. ka tests fçr ~ first ~ssessment çf mech~nic~l beh~viçur çf the stçneJcçvered f~ç~des çf m~l~zzç auc~le in senice. fnW mrçceedings çf the Vth pqobjAe CçnferenceI Chi~nci~nç qermeI ft~lyI peptember RJTI OMNN.

xPz Bçsc~tçI d.I oussçI p.I pci~rrett~I c. EOMNNF. ptructur~l jçnitçring çf the plender açubleJi~yered c~ç~de çf m~l~zzç auc~le in senice – mrelimin~ry An~lysis çf je~surements. j~sçnry fntern~tiçn~lI sçl O4I kç.PI RTJTSI OMNO.