seismic chilean damges licuefaction

7/23/2019 Seismic Chilean Damges Licuefaction

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Statistical Analysis of Underpasses Damaged During 2010Chile Earthquake

Felipe Toro, Felipe Rubilar, Matias A. Hube, Hernn Santa-Mara

and Tamara Cabrera

ABS !AC

Approximately 3 brid!es, representin! less t"an 3# o$ t"e total number o$ C"ilean brid!es, %ere dama!ed durin! t"e & ' Maule eart"(ua)e. From t"ese dama!ed brid!es, %"i*"in*lude pedestrian brid!es, & su$$ered *ollapsed spans. T"e ob+e*ti e o$ t"is study is to *ondu*t astatisti*al analysis o$ t"e underpasses lo*ated in a representati e se*tion o$ t"e main route .T"is analysis is aimed to *orrelate t"e brid!e *"ara*teristi*s %it" t"e obser ed dama!e le el. /aststudies re eal t"at t"is type o$ post-eart"(ua)e analysis is a robust tool to nurture t"e de*ision-ma)in! pro*ess $or up!radin! ulnerable stru*tures and $or !uidin! $uture per$orman*e based

en!ineerin! studies. To *ondu*t t"e statisti*al analysis a database %as built %it" t"e underpasses*"ara*teristi*s su*" as lo*ation, presen*e or absen*e o$ rein$or*ed *on*rete 0RC1 stoppers or *on*rete lids, s)e% an!le, and seismi* 2one. Additionally, t"e database in*ludes t"e des*ription o$ dama!e, t"e re(uired repairin! a*tion, and t"e estimated repairin! *ost. From t"is study it is*on*luded t"at *riti*al ariables a$$e*tin! t"e underpasses be"a iour are t"e presen*e or absen*e o$ stoppers, t"e s)e% an!le, and t"e lo*ation o$ t"e brid!e. rid!es %it" *on*rete lids s"ould bea oided be*ause t"eir repairin! *ost is "i!"er t"an t"e repairin! *ost o$ brid!es %it" RC stoppersand "a e a lar!er probability o$ *ollapse T"e a era!e repairin! *ost $or t"e *onsidered underpassesis estimated in ''# o$ t"eir *onstru*tion *ost and t"e s)e%ed underpasses %ere more ulnerablet"an non s)e%ed brid!es be*ause t"eir repairin! *ost is "i!"er.

4444444444 Hernn Santa-Mara, Asso*iated /ro$essor, /5C, 6i*u7a Ma*)enna 8 9 , Santia!o, C"ileMatias A. Hube, Assistant /ro$essor, /5C, 6i*u7a Ma*)enna 8 9 , Santia!o, C"ileFelipe Rubilar, :raduated Student, /5C, 6i*u7a Ma*)enna 8 9 , Santia!oFelipe Toro, :raduated Student, /5C, 6i*u7a Ma*)enna 8 9 , Santia!o, C"ileTamara Cabrera, /ro+e*t Re ie%er ;n!ineer, M


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"# !$DUC "$#

A M% , C"ile eart"(ua)e o**urred on February &= t", & ' , in t"e *entral sout"ern re!iono$ Maule 0 oros*"e) et al., & '&1. More t"an a t"ird o$ a million buildin!s %ere dama!ed to

aryin! de!rees, in*ludin! some *ases o$ total *ollapse o$ ma+or stru*tures 0;lnas"ai et al., & '&1.

T"e transportation system re!istered 3 $ailures on roads in bot" t"e publi* and pri atetransportation net%or)s. s, typi*al brid!e desi!ns $or underpasses "a e been e ol in!. e$ore t"e > s brid!e desi!n *onsisted o$ simply supported /C!irders, %it" a rein$or*ed *on*rete 0RC1 slab, trans erse RC diap"ra!ms at t"e supports, RCstoppers, and erti*al bars or "old do%ns $or pre entin! upli$t 0Fi!ure &a1. Gn t"e ne% desi!n, t"eRC diap"ra!m %as eliminated, as s"o%n in Fi!ure &b. Additionally, in some brid!es t"e RCstopper %as repla*ed by a *on*rete *o er, or lid, %it" a small !ap bet%een t"e /C !irder and t"e*o er, as s"o%n in Fi!ure &*. T"e stru*tural di$$eren*e bet%een t"e latter t%o *on$i!urations isexplained later. Gt is important to note t"at in ot"er dama!ed underpasses, not *onsidered in t"isstudy, t"e RC stoppers and t"e erti*al "old do%ns %ere repla*ed by steel stoppers $or pre entin!

bot" t"e trans erse displa*ement and t"e erti*al upli$t 0Hube and Rubilar, & ''1. Mostunderpasses *onsidered in t"is statisti*al analysis "a e t"e stru*tural *on$i!urations s"o%n inFi!ure &b and &*, %it"out diap"ra!m.

&


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Fi!ure '. Representati e 5nderpass. Sour*e? :oo!le ;art"

a1 Typi*al desi!n be$ore t"e > s b1 e% desi!n %it"out diap"ra!m

*1 e% desi!n %it"out diap"ra!m and %it" *on*rete lids

Fi!ure &? Cross Se*tions o$ 5nderpasses

B!"D%E DES"%# C$DE A#D C$#S !UC "$# &!AC "CES

T"e C"ilean brid!e desi!n *ode at t"e time o$ t"e eart"(ua)e 0M


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t"e de*). T"e "old do%ns are desi!ned %it" a erti*al *oe$$i*ient o$ K vJ Ao@& g ne!le*tin! t"e e$$e*to$ t"e dead load, and t"ey must be at least && mm in diameter. Ho%e er, t"e desi!n *ode does notspe*i$y a prestressin! $or*e $or t"ese "old do%ns. Trans erse diap"ra!ms are re(uired to maintaint"e !eometri* se*tion o$ t"e de*). Ho%e er, t"ese diap"ra!ms *an be eliminated in seismi* 2ones 'and & i$ an ade(uate per$orman*e o$ t"e brid!e *an be demonstrated.

To limit trans ersal displa*ement o$ t"e superstru*ture, brid!es are usually pro ided %it"lateral stoppers. A stopper is a stru*tural element lo*ated at t"e abutment or *ap-beam and it islo*ated at t"e side o$ t"e exterior !irder, or in some *ases, in bet%een t"e !irders. A RC stopper att"e end o$ a *ap beam $or a brid!e o$ t"e presented database is s"o%n Fi!ure 3a. A**ordin! to t"edesi!n *ode 0M


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B!"D%E DA ABASE

As t"e dama!e in o erpasses %as distributed t"rou!" di$$erent "i!"%ays alon! t"e *ountry,in$ormation o$ all underpasses lo*ated in a representati e se*tion o$ t"e main route %as*onsolidated into one database. T"e database o$ underpasses %as *onstru*ted usin! stru*tural

dra%in!s, dama!e inspe*tion reports and soil me*"ani*s reports o$ most underpasses. T"isin$ormation %as obtained %it" t"e support o$ M


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Fi!ure . :irder ama!e Le els

SU''A!( $) B!"D%E &E!)$!'A#CE A#D S A (S "CA* A#A*(S"S

T"e statisti*al analysis o$ t"e underpasses lo*ated in a se*tion o$ Route is des*ribed int"is se*tion. From t"ese brid!es, >=# %ere *onstru*ted %it" no trans erse diap"ra!ms, e ent"ou!" &8 o$ t"em are lo*ated in seismi* 2one 3 %"ere t"e use o$ diap"ra!ms is mandatory 0M


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Fi!ure 9. umber o$ ama!ed rid!es %it" Con*rete Lids or RC Stoppers

T"e per*enta!e o$ brid!es %it" ea*" dama!e le el o$ t"e !irders is s"o%n in Fi!ure =. T"e$i!ure s"o%s t"at !irders in brid!es %it" *on*rete lids %ere less dama!ed t"an t"ose in brid!es%it" RC stoppers? = # and 8 # o$ underpasses "ad undama!ed !irders $or brid!es %it" *on*retelids and RC stoppers, respe*ti ely. Additionally, t"e per*enta!e o$ brid!es %it" L-8 %as and

# $or brid!es %it" *on*rete lids and RC stoppers, respe*ti ely. T"e lar!er dama!e in !irders o$ brid!es %it" RC stoppers %as indu*ed by t"e impa*t o$ t"e bottom $lan!e o$ t"e !irder a!ainst t"eRC stopper durin! t"e eart"(ua)e. T"e !irders o$ brid!es %it" *on*rete lids "ad redu*ed dama!e

be*ause t"e impa*t $or*e indu*ed by t"e %ea)er *on*rete lids %as small. Gt is important to note t"atmost brid!es *onsidered on t"is database 0>=#1 "ad no trans erse diap"ra!m. T"ere$ore, t"etrans erse $or*e in t"e !irder indu*ed by t"e impa*t bet%een t"e bottom $lan!e and t"e stoppers or *on*rete lids "ad to be resisted entirely by a sin!le !irderB it %as not distributed to all t"e !irders asit is t"e *ase $or brid!es %it" trans erse diap"ra!ms.

Fi!ure =. :irder ama!e on rid!es %it" Con*rete Lids or RC Stoppers

=


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T"e per*enta!e o$ brid!es t"at e iden*ed lar!e displa*ement or rotation o$ t"esuperstru*ture %as & and '3# $or brid!es %it" *on*rete lids and RC stoppers, respe*ti ely. Adispla*ement or rotation o$ t"e superstru*ture %as *onsidered lar!e %"en it re(uired to be ali!ned

ba*) to t"e ori!inal position. As a rule o$ t"umb, M, and >, respe*ti ely. Most o$ t"e underpasses o$ t"e database "a e no s)e%. T"e

per*enta!e o$ underpasses $or ea*" s)e% an!le *ate!ory %it" di$$erent brid!e dama!e le el iss"o%n in Fi!ure . T"is $i!ure s"o%s t"at brid!es %it" ne!li!ible s)e% did not *ollapse. 1 and ''# 0' out o$ >1 o$ brid!es *ollapsed %it" small s)e% an!le and

lar!e s)e% an!le, respe*ti ely. Finally, Fi!ure s"o%s t"at brid!es %it" lar!e s)e% an!le presented t"e lar!er dispersion in t"e distribution o$ dama!e le el, %it" &, 33#, 33#, and ''#o$ brid!es %it" dama!e le el L-', L-&, L-3, and L-8, respe*ti ely.

Fi!ure . ama!e Le el o$ rid!es %it" i$$erent S)e% An!le

T"e per*enta!e o$ brid!es t"at s"o%ed lar!e displa*ement or rotation o$ t"e superstru*ture%as &9# and '3# $or brid!es %it" s)e% and %it" ne!li!ible s)e% an!le, respe*ti ely. T"ere$ore, itis *on*luded t"at t"e s)e% an!le $a*ilitated t"e displa*ement or rotation o$ t"e superstru*ture.

Seismic ,a-ard Definition

T"e seismi* "a2ard $or brid!es is spe*i$ied in t"e brid!e desi!n *ode 0M


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%it" an e$$e*ti e a**eleration o$ .8!. T"e middle and east o$ t"e *ountry are de$ined as seismi*2ones & and ', respe*ti ely, %it" e$$e*ti e a**elerations o$ .3! and .&!, respe*ti ely. T"ede$inition o$ t"ese dis*rete seismi* 2ones a$$e*ts t"e desi!n o$ brid!es, %"ere di$$erent dis*rete

alues o$ t"e seismi* *oe$$i*ient are used at di$$erent seismi* 2ones. T"e number o$ underpasses o$ t"e database lo*ated in seismi* 2ones 3 and & are &8 and 98 brid!es, respe*ti ely. T"e per*enta!e

o$ underpasses lo*ated in ea*" seismi* 2one, %it" di$$erent brid!e dama!e le el is s"o%n in Fi!ure>. T"is $i!ure s"o%s t"at t"e per*enta!e o$ undama!ed brid!es 0 L-'1 is similar $or brid!eslo*ated in bot" seismi* 2ones. T"e t"ree underpasses o$ t"e database t"at *ollapsed 0 L-81 are alllo*ated in seismi* 2one &, %"i*" represents # o$ t"e brid!es in t"is 2one. Gt is important to notet"at t"e *ollapsed brid!es %ere desi!ned %it" a lateral $or*e 33# smaller t"an t"at o$ brid!eslo*ated in seismi* 2one 3.

Fi!ure >. ama!e Le el o$ rid!es Lo*ated in i$$erent Seismi* Nones

T"e lo*ation o$ t"e underpasses *onsidered in t"is %or), and t"e seismi* 2ones 3 and &, ares"o%n in Fi!ure ' . Gn t"is re!ion o$ t"e *ountry, %it" a len!t" o$ about 8 )m, t"ere is noseismi* 2one '. T"e seismi* 2ones are de$ined on t"e *ode $or ea*" Muni*ipality 0G , '>>91Bt"ere$ore, t%o brid!es lo*ated ery *lose to ea*" ot"er, but at t%o ad+a*ent Muni*ipalities, may"a e a lar!e di$$eren*e on seismi* "a2ard be*ause o$ t"e dis*rete alue in t"e e$$e*ti e a**eleration.Gn $a*t, t"e borders o$ t"e Muni*ipalities do not *orrelate %it" t"e distan*e to t"e o*ean tren*", nor to t"e distan*e o$ *rustal $aults. T"is $a*t re eals t"e ur!ent need to de elop a ne% and *ontinuousseismi* "a2ard map in C"ile. T"e brid!es lo*ated in seismi* 2one 3, %"i*" are lo*ated near t"e*ities o$ Tal*a and C"illn, "a e similar distan*e to t"e o*ean tren*" and to t"e rupture area0 oros*"e) et al., & '&1 t"an t"e rest o$ t"e brid!es o$ t"e databaseB "o%e er, t"ey %ere desi!ned%it" a 33# lar!er lateral load t"an t"ose brid!es lo*ated in seismi* 2one &.

T"e dama!e le els o$ t"e underpasses are s"o%n in Fi!ure ' %it" di$$erent *olors. T"e$i!ure s"o%s t"at t"e most dama!ed underpasses, in*ludin! t"ree *ollapses, %ere lo*ated bet%een8 and )m sout" o$ Santia!o. :eote*"ni*al site e$$e*ts may explain t"ese lo*ali2ed dama!es.T"ese site e$$e*ts %ill be studied in t"e $uture by measurin! soil s"ear %a e elo*ities at t"elo*ation o$ ea*" underpass.

>


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Fi!ure ' . Lo*ation o$ ama!ed rid!es and e$inition o$ Seismi* Nones? Seismi* None 3 s"o%n%it" ar) :rey and Seismi* None & s"o%n %it" Li!"t !ray

!E&A"!"#% C$S S

T"e detailed repairin! a*tion $or ea*" underpass a$ter t"e eart"(ua)e %as obtained $romM


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T"e estimated repairin! *ost o$ t"e underpasses *onsidered in t"is study aries $rom # to'& # o$ t"e brid!e *ost, and t"e a era!e repairin! *ost is ''#. A repairin! *ost o$ '& # o$ t"e*ost o$ a ne% brid!e is assi!ned to brid!es %it" dama!e L-8 be*ause o$ t"e demolition *ost. T"ea era!e repairin! *osts $or brid!es %it" *on*rete lids and RC stoppers are '8# and ' #,respe*ti ely. T"ese results su!!est t"at *on*rete lids s"ould be a oided and t"at brid!es s"ould be

desi!ned %it" stoppers. T"e a era!e repairin! *ost $or s)e%ed 0an!le o$ s)e% lar!er t"an 1 andnon-s)e%ed brid!es are &9# and =#, %"i*" means t"at s)e%ed brid!es are more ulnerable t"annon-s)e%ed brid!es. Finally, t"e a era!e repairin! *osts $or brid!es lo*ated in seismi* 2ones & and3 are '3# and =#, respe*ti ely. T"e last result is *onsistent %it" t"e $a*t t"at brid!es in seismi*2one 3 %ere desi!ned %it" "i!"er seismi* demand.

C$#C*USS"$#S

A statisti*al analysis o$ t"e underpasses lo*ated is *ondu*ted in t"is resear*". T"e main*on*lusions $rom t"is study are? rid!es pro ided %it" RC stoppers did not *ollapse. Ho%e er, '3# o$ brid!es %it" RC

stoppers %ere undama!ed, %"ile 38# o$ brid!es %it"out RC stoppers 0%it" *on*rete lids1 %ereundama!ed. S)e%ed brid!es presented lar!er dispersion in brid!e dama!e t"an non-s)e%ed brid!es. T"e

per*enta!e o$ brid!es %it" displa*ement or rotation o$ t"e superstru*ture %as &9# and '3# $or s)e%ed, and non-s)e%ed brid!es, respe*ti ely.

T"e dis*rete de$inition o$ t"e seismi* "a2ard le el in C"ile in$luen*ed t"e brid!e be"a ior. T"et"ree brid!es o$ t"e database t"at *ollapsed %ere lo*ated in a seismi* 2one %it" a lo%er e$$e*ti e a**eleration. T"ere is an ur!ent need to de elop a ne% and *ontinuous seismi* "a2ardmap in C"ile.

T"e a era!e repairin! *ost $or t"e underpasses is estimated in ''# o$ t"eir *onstru*tion *ost. rid!es %it" *on*rete lids s"ould be a oided be*ause t"eir repairin! *ost is "i!"er t"an t"e

repairin! *ost o$ brid!es %it" RC stoppers and "a e a lar!er probability o$ *ollapse. T"e a era!e repairin! *osts $or s)e%ed and non-s)e%ed brid!es are &9# and =# o$ t"eir

*onstru*tion *ost, respe*ti ely. S)e%ed brid!es are more ulnerable t"an non-s)e%ed brid!es,and t"at *urrent C"ilean desi!n pro isions s"ould be re ised to pro ide uni$orm ulnerabilityto bot" type o$ brid!es.

AC.#$/*ED%E'E# S

T"is resear*" %as supported by t"e C"ilean ational Commission $or S*ienti$i* andTe*"nolo!i*al Resear*" 0C< GCDT1 t"rou!" pro+e*ts F< ;F ' i' &= and F< ;CDTO'''&' '.

!E)E!E#CES

Ameri*an Asso*iation o$ State and Hi!"%ay Transportation


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u*)le, G., Hube, M., C"en, :., Den, K., and Arias, ., 0& ''1, PStru*tural /er$orman*e o$ rid!es in t"e-&8 .a%as"ima, ., 5n+o", S., Hos"i)uma, . and osa, ., 0& ''1. P ama!e o$ rid!es due to t"e & '

Maule, C"ile, ;art"(ua)e,Q Journal of Earthquake Engineering , ' 0=1, pp. ' 39-' 9 .Hube, M., Santa-Mara, H. and 6illalobos, F. 0& ' 1. P/reliminary analysis o$ t"e seismi* response o$

brid!es durin! t"e C"ilean &= February & ' eart"(ua)e,Q >91, P ise7o Ssmi*o de ;di$i*ios, C"833.

seismic chilean damges licuefaction

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