Parsons Brinckerhoff Consruction

8/19/2019 Parsons Brinckerhoff Consruction

1/43


2/43

and construction o! segmental concrete bridges The success!ul

bid !or the bridge structures was & percent below the lowest

steel alternate and the pro*ect was completed 1" months

earlier than the speci,ed contract time o! years

Since "a# of $%%&' motorists tra(eling t)e nort) eastern

corridor of Interstate %* t)ro+g) Ne! England )a(e en,o#ed t)e

m+c) needed l++r# of t)e additional tra(el lanes -ro(ided b#

t)e com-letion of t)e Ra#mond E. Bald!in Bridge in

Connectic+t /see Fig. $0. T)e ne! str+ct+res t)at s-an t)e

mo+t) of t)e -ristine Connectic+t Ri(er' bet!een t)e to!ns of

Old Sa#broo1 and Old 2#me' )a(e relie(ed some of t)e tra3c

congestion t)at -lag+es t)is tra(el !a#' es-eciall# in t)e-o-+lar s+mmer and colorf+l fall mont)s.

In 4an+ar# of $%%5' t)e Connectic+t 6e-artment of

Trans-ortation a!arded t)e contract to b+ild t)e ne! Bald!in

Bridge to t)e 4oint 7ent+re of PeriniPC28O9:. T)e 4oint 7ent+re

-ro(ided a lo! bid of ;%&.< million to b+ild t)e concrete

alternate= a -recast concrete segmental s+-erstr+ct+re

s+--orted on cast8in8-lace concrete -iers. T)e 4oint 7ent+re

!as t)e onl# bidder to -ro(ide a -rice for t)e concrete

alternate. All ot)er bidders s+bmitted a -rice for t)e s+--osedl#

more -o-+lar and economical steel girder alternate /see Table

$0.T)e bridge b+ilding ind+str#' along !it) t)e Connectic+t

6e-artment of Trans-ortation' !as (er# s+r-rised at t)e

o+tcome of t)e bid. In addition' t)e 6e-artment !as a little

a--re)ensi(e abo+t )a(ing a -recast segmental concrete

str+ct+re b+ilt in t)eir state since' at t)e time' segmental

str+ct+res !ere recei(ing mied re(ie!s from trade maga>ines

and sce-tical contractors.


3/43

Fig.$ O(erall (ie! of Ra#mond E. Bald!in Bridge nearing

com-letion

Table $ Bids for t)e Bald!in Bridge -ro,ect

To assist t)e 6e-artment in managing t)e constr+ction of t)is

state8of8t)e8art str+ct+re' t)e# a!arded a constr+ction

engineering and ins-ection contract to a ,oint (ent+re of

Parsons Brinc1er)o? Constr+ction Ser(ices' Herndon' 7irginia'

and a local engineering and s+r(e# @rm' 28C 9 Associates. T)e

6e-artment also retained t)e bridge designer' Parsons

Brinc1er)o? +ade and 6o+glas' Hartford' Connectic+t' for

-ost8design ser(ices and on8site tec)nical assistance.

PROJECT DETAILS

Soon after notice to -roceed )ad been gi(en' t)e 4oint 7ent+re

informed t)e o!ner of t)eir intention to s+bmit an earl#

com-letion sc)ed+le and @nis) t)e -ro,ect $ mont)s a)ead of

t)e contracted d+ration of < mont)s. T)is accelerated


4/43

constr+ction sc)ed+le !as to be s+--orted and made -ossible

b# a modi@cation to t)e erection met)od s)o!n in t)e contract

-lans.

Fig. Pro@le of Bald!in Bridge


5/43

Fig. & T#-ical -iers !it) t)e dec1 segments in -lace

T)e -ro-osed modi@cation called for t)e balanced cantile(er

erection to be -erformed +sing a f+ll# a+tomated o(er)ead

erection tr+ss to -lace t)e -recast concrete segments' instead

of t)e modi@ed beam and !inc) met)od s)o!n in t)e contract

doc+ments. T)e o(er)ead erection tr+ss !o+ld erect t)e

!estbo+nd str+ct+re @rst and t)en it !o+ld be trans-orted bac1

o(er t)e com-leted bridge and +sed again to erect t)e

eastbo+nd str+ct+re.

Eac) bridge is an $$8s-an' contin+o+s +nit consisting of

constant de-t) -recast concrete bo girder segments. T#-ical

s-an lengt)s are * ft /D* m0 non8t#-ical s-ans range from

$DD ft in. /* m0 at t)e !est ab+tment to D* ft /ed t)e n+mber of di?erent t#-es of

segments to fo+r= -ier /50' ab+tment /0' T#-e GBG /%0' T#-e

GAG /&D*0. T)e T#-e GBG segments are erected ad,acent to t)e

-ier and ab+tment segments. All dra-ed cantile(er tendons

-ass t)ro+g) t)e -ier segment dia-)ragms and anc)or in t)e

tendon de(iation bloc1s at t)e lo!er comer of t)e T#-e GBG


6/43

segments /see Fig. &0. T)e remainder of t)e cantile(ers

com-rise (ar#ing n+mbers of T#-e GAG segments. T)ese

segments are connected to t)e cantile(ers !it) to- slab

cantile(er tendons and !it) to- and bottom slab contin+it#

tendons.

Box Girder Segments

T)e -recast road!a# segments for t)e Bald!in Bridge are t)e

second largest single cell bo girder segments cast in t)e

United States. T)e tra-e>oidal cross section of t)e segment is

sti?ened trans(ersel# b# inclined -recast concrete str+ts. T)e

designer c)ose to +se t)e inclined str+ts instead of m+lti-le(ertical !eb !alls beca+se it !as considered more str+ct+rall#

e3cient and made t)e segment lig)ter and less di3c+lt to

fabricate.

Eac) segment is $$ ft. < &< in. /&. m0 in )eig)t and D ft < in.

/.< m0 in !idt) for t)e eastbo+nd bridge and


7/43

"+lti-le s)ear 1e#s are +tili>ed on t)e !eb !all face along !it)

indi(id+al s)ear and alignment 1e#s along t)e to- and bottom

slabs. T)e !eb t)ic1ness is a constant & in. /*


8/43

Fig. T#-ical cross section of t)e s+-erstr+ct+re

Fig. * casting #ard la#o+t

T)e to- slabs of all segments are -ost8tensioned in t)e

trans(erse direction !it) fo+r8strand tendons. T)ese tendons

!ere stressed at a minim+m concrete strengt) of *55 -si /$D

"Pa0. Beca+se of t)is' and d+e to t)e )ig) b+rsting stresses at

t)e anc)orage location' -recast concrete edge beams !ere

+sed at eac) end of t)e to- slab to -ro(ide **55 -si /&< "Pa0

concrete strengt) in t)is area. T)is feat+re !as also +sed


9/43

s+ccessf+ll# in t)e S+n s)ine S1#!a# Bridge o(er Tam-a Ba#'

Florida.

T#-icall#' fo+r8strand loo- tendons !ere +sed to -ost8tension

t)e !eb and bottom slab areas. 6+e to t)e etreme c+r(at+reof t)ese tendons' t)e# !ere stressed sim+ltaneo+sl# from bot)

ends. T)e bottom slab !as additionall# -ost8tensioned along its

centerline !it) a single m+lti8strand tendon. A trans(erse rib

!as -ro(ided on t)e bottom slab to s+--l# s-ace for t)is

tendon. T)e dia-)ragm section and str+ts of t)e -ier and

ab+tment +nits are also -osttensioned in t)e trans(erse

direction !it) m+lti-le m+lti8strand tendons.

All -ost8tensioning tendons consisted of 5.* in /$& mm0

diameter' D5 -si /$


10/43

Beca+se t)ere !ere t)ree t#-es of segments to fabricate' t)e

contractor +sed t)ree segment assembl# lines. T)e assembl#

lines !ere set +- ad,acent to one anot)er in a nort)8so+t)

orientation. Eac) -rod+ction line com-rised one set of c+stom

made forms s+--orted b# t!o reinforcing steel ,igsassembl#

frames.

Fig. S)ort8line matc) casting of segments


11/43


12/43

Fig. % t#-ical reinforcing steel la#o+t ,ig


13/43

Fig. $5 Prefabricated steel cage being lifted into casting mac)ine

Sit+ated bet!een t)e casting beds and t)e reinforcing steel

fabrication area !as a mobile' rail8mo+nted to!er crane. T)iscrane -ro(ided s+--ort to all t)ree -rod+ction lines. It !as +sed

to )andle all materials' install t)e -refabricated reinforcing

steel cages' and relocate t)e segment so3t forms in eac)

casting bed. T)e to!er crane co+ld )andle a maim+m load of

$* tons /$ t0 o-erating on a $55 ft /&5m0 radi+s.

As segments !ere -rod+ced b# t)e s)ort8line casting met)od'

t)e# !ere rolled to t)e end of t)e -rod+ction line and )a+led

into storage /see Fig. 0. T)e original storage area -ro(ided

eno+g) ca-acit# to store $&5 segments /see Fig. D0.

T)e contractor )eld a *8acre /.5 )a0 section of t)e #ard in

reser(e in case t)ere !ere dela#s in t)e erection -rocess. T)is

-ro(ed to be a (er# -r+dent -lan on t)e contractors -art. In

4+l# of $%%$' t)e initial storage area !as f+ll and t)e erection

-rocess )ad not #et beg+n. T)e contractor t)en c)ose to

eercise )is o-tion and clear t)e remainder of t)e a(ailableland' !)ic) -ro(ided storage ca-acit# for *5 additional


14/43

segments. If it !ere not for t)is additional storage area' t)e

-rod+ction of segments !o+ld )a(e been discontin+ed +ntil t)e

erection -rocess began' & mont)s later.

Segments !ere mo(ed from casting bed to casting bed and)a+led into storage !it) a c+stom made &558ton /D t0 S)+ttle

2ift tra(el crane /see Fig. ed for segment storage rat)er t)an for access r+n!a#s.

Prod!tion Area

All reinforcing steel and -osttensioning d+cts for eac) T#-e GAG

and T#-e GBG segment !ere installed in -refabrication ,igs /see

Fig. %0. Beca+se t)e reinforcing steel and -ost8tensioning items

!ere tied in t)e form!or1 for t)e -ier and ab+tment segments'

t)ree ,igs !ere initiall# a(ailable for +se for t)e T#-e GAG and T#-e GBG segments. Once all t)e -ier and ab+tment segments

)ad been cast' t)e casting form !as con(erted to -rod+ce T#-e

GAG segments' !it) eac) form t)en being s+--orted b# t!o ,igs.

T)e +se of m+lti-le ,igs too1 fabrication of t)e reinforcing steel

cages o? t)e critical -at) and -ro(ided for a small amo+nt of

lag time bet!een t)e fabrication of t)e cage and t)e need to

install it in t)e form!or1. T)is lag allo!ed for m+c) needed

contingenc# time for -rod+ction related -roblems' s+c) as steel

fabrication errors and material deli(er# dela#s.

Eac) ,ig !as made of (ario+s standard steel s)a-es' !it)

-l#!ood faces to acc+ratel# sim+late t)e eterior dimensions

and cross section of a segment. A !ooden b+l1)ead sim+lated

t)e segment cross section and !as mar1ed acc+ratel# !it) t)e

t#-ical locations of longit+dinal -ost8tensioning anc)orages and

d+ct locations. T)is allo!ed t)e re+ired embedded items to be


15/43

acc+ratel# -laced in t)e ,ig !it)in acce-table @eld tolerances. It

!as im-erati(e t)at as m+c) !or1 as -ossible be done in t)e

-refabrication area so t)at critical -rod+ction time in t)e

form!or1 area co+ld be +sed strictl# for form !or1 and

segment set+-.

T)e -recast concrete str+ts and edge beams !ere t)e @rst

items to be -laced in t)e ,igs. A cre! of t!o car-enters -laced

t)ese items' and set t)e re+ired -ost8tensioning anc)orages

and -re-ared t)e ,ig area for t)e steel t#ing cre!. T#-icall#' a

cre! of si iron!or1ers tied D555 to $'555 lbs /5


16/43

b# Concrete Forms Cons+ltants' Ha!le#' Penns#l(ania' and !as

fabricated b# Transfab' H+ntington' Jest 7irginia. Eac) set of

forms consisted of t)ree mo(able so3ts' a @ed b+l1)ead'

ad,+stable !ing forms' and a retractable inner core form.

T)e contractor -roc+red t)ree so3t forms in order to ta1e t)e

remo(al of cast segments to storage o? t)e critical -at) of

-rod+ction. Eac) so3t !as f+ll# e+i--ed !it) )#dra+lic ,ac1s

to s+--ort and mani-+late t)e matc)8cast segment to its

-ro-er orientation in t)e casting bed. T)e so3t forms !ere

s+--orted on rail8mo+nted Hillman rollers for smoot) and

sim-li@ed mo(ement. A front end loader -+lled t)e segment in

and o+t of its matc)cast -osition.

T)e steel b+l1)ead !as rigidl# s+--orted and @ed to a

concrete fo+ndation. After t)e initial set+-' no ad,+stments to

t)e b+l1)ead !ere necessar#. T)e segment !ing forms !ere

-inned at t)e bottom' near t)e so3t area' and !ere made

ad,+stable at t)e rear b# +se of )#dra+lic ,ac1s. Onl# (ertical

mo(ement of t)e side forms !as necessar# for stri--ing of t)e

+nit. T)e inner form !as s+--orted in cantile(er b# a mo(able

steel s+--ort frame.

T)e s+--ort frame !as also mo+nted on Hillman rollers and

!as o+t@tted !it) )#dra+lic ,ac1s to raise and lo!er t)e inner

core form -rior to installing or retracting t)e assembl#. 6+e to

s-ace limitations' t)e inner core s+--ort frame !as

mani-+lated into -osition b# a )#dra+lic -+s)8-+ll c#linder

mo+nted +nder t)e assembl# frame !it) t)e -iston rod

anc)ored to t)e concrete fo+ndation. T)is -ro(ed to be a (er#e?ecti(e and economical !a# to mo(e t)e inner core s#stem in

and o+t of t)e casting -osition.

T)e inner core forms !ere also o+t@tted !it) )#dra+lic ,ac1s to

f+ll# a+tomate t)e -lacement and stri--ing o-erations. All

form!or1 )#dra+lics !as o-erated from a centrall# located

control +nit. "iscellaneo+s form!or1 for t)e bottom slab

trans(erse rib and local areas aro+nd t)e -recast str+t


17/43

connections' at t)e to- slab and at de(iation bloc1 areas' !as

-laced b# )and.

T)e s-eed of form!or1 mani-+lation ,+sti@ed t)e additional

e-ense for t)e etensi(e )#dra+lic -ac1ages. A t#-ical -recastsegment !as stri--ed and -+lled o+t of t)e casting -osition

!it)in a 8)o+r -eriod' +s+all# bet!een =&5 a.m. and


18/43

T)e GBG segments !ere -rod+ced on a and &8 da# c#cle' and

t)e GAG segments !ere -rod+ced on a dail# basis. Jor1ing a *8

da# !or1 !ee1' t)e contractor ro+tinel# -rod+ced 5 GAG

segments' < GBG segments' and -ier segments' for a total of

&5 segments -er mont).

Fig. $$ Setting forms for t)e matc)8casting o-eration.


19/43

Fig. $ Concrete -lacement !it) a mobile -+m-ing +nit c+ring blan1ets

-ro(ide steam c+ring enclos+re.

T)e contractor started casting segments in No(ember $%%5'

d+ring !)at local Connectic+t residents called a mild !inter. T)e -rod+ction Glearning c+r(eG lasted a--roimatel# !ee1s'

!)ic) !ere fairl# s)ort for casting large segments !it) t)is

t#-e of cross section. T)e s)ort d+ration of t)e learning c+r(e

!as attrib+table to an e-erienced s+-er(isor# sta?' +ic1

learning b# local +nion trades' and a -rod+ction s#stem t)at

!as laid o+t !ell and -ro(ided for maim+m e3cienc#.

Con!rete P&a!ement

Concrete !as deli(ered to t)e casting #ard in I 5 c+ #d. /D .

m&0 front disc)arge read# mi tr+c1s b# t)e local concrete

-rod+cer. After re(ie!ing t)eir o-tions' t)e contractor c)ose to

-+m- concrete instead of setting +- a con(e#or s#stem t)at

!o+ld )a(e ser(ed all t)ree casting beds. All concrete !as

-laced !it) a Sc)!ing -+m- tr+c1 /see Fig. $0.Concrete !as @rst -laced in t)e lo!er corner of a segment and

t)e str+t bloc1 area /tendon de(iation bloc10' follo!ed b# t)e

bottom slab and trans(erse rib. At t)is time' t)e se(en8man

concrete cre! mo(ed on to- of t)e segment to -o+r bot) !eb

!alls.


20/43

Fig. $& Precast concrete segment loaded on %8!)eel trailer for trans-ort

to site.

T)is se+ence allo!ed t)e bottom slab and lo!er !eb !alls to

set+- slig)tl# and )el-s s+--ort t)e concrete -+m-ed into t)e

!eb !alls t)at !ere on a D*8degree incline. Once t)e !eb !alls

!ere to--ed o+t' t)e dec1 !as -laced from one end to t)e

ot)er. T)e dec1 s+rface !as le(elled o? !it) a man+all#

o-erated longit+dinal screed. T)e dec1 t)en recei(ed a b+ll

Loat @nis).

A smoot) s+rface @nis) !as s-eci@ed beca+se t)e s+rface

o(erla# began !it) a membrane t#-e as-)alt liner t)at

re+ired a smoot) +nderl#ing s+rface. All concrete !as

consolidated !it) man+all# o-erated internal (ibrators no

eternal (ibration !as necessar#. From start to @nis)' t)econcrete -lacement !as accom-lis)ed in a M to &8)o+r

-eriod.

T)e concrete mi design consisted of D5* lbs /$< 1g0 of T#-e I

cement' $. /5.$ litres0 of air entrainment'

$. o>. /5.& litres0 of set retarder and $5 o>. /& .$& litres0 of JR6A $% )ig) range !ater red+cer. All admit+res !ere


21/43

introd+ced into t)e mi at t)e batc) -lant. T)e target sl+m- for

t)is mi !as .* in. $.* in. /$* mm &< mm0. T)e +se of t)e

)ig) range !ater red+cer allo!ed for ease of -lacement' less

(ibration d+ring consolidation' and lo!er !ater8cement ratio to

)el- ens+re a )ig) earl# strengt) concrete.

T)e concrete !as c+red !it) lo! -ress+re steam to g+arantee

minim+m *55 -si /$D "Pa0 strengt) at =&5 a.m.' t)e morning

follo!ing t)e -o+r. Concrete strengt)s of &D55 -si /*.* "Pa0

!ere act+all# ac)ie(ed after a relati(el# s)ort steam c#cle t)at

incl+ded a &8)o+r -re)eat -eriod to ac)ie(e initial set' follo!ed

b# a grad+al rise to a maim+m tem-erat+re of $55 to l5F

/&ing.No crac1ing from Gt)ermal s)oc1G !as e-erienced on t)ese

segments. T)is !as most li1el# d+e to t)e relati(el# small

t)ic1nesses of t)e concrete sections on t)e t#-ical GAG and GBG

segments. Beca+se of t)eir t)ic1 dia-)ragm sections' -ier and

ab+tment segments remained -artiall# co(ered !it) concrete

c+ring blan1ets for to & da#s. T)is -ro(ided t)e necessar#

-rotection to t)e ft. /$. m0 t)ic1 dia-)ragms and )el-ed

minimi>e an# crac1ing d+e to large tem-erat+re di?erentials.


22/43

TRANSPORTATION AND ERECTION

Segment Trans'ort T)e &558ton /D t0 S)+ttle 2ift !as +sed to load t)e segments

on a s-ecial $8ale' %8!)eel )#dra+lic trailer c)osen b# t)e

4oint 7ent+re to trans-ort t)e segments from t)e casting #ard

to t)e erection site /see Fig. $&0.


23/43

Fig. $ /a0 2a+nc)ing gantr# for -lacing segmental boes /b0 to /d0 Ste-s

to mo(e gantr# to cantile(er erection -osition


24/43

Fig. $ /cont.0 2a+nc)ing gantr# for -lacing segmental boes /e0 to /)0

Ste-s to mo(e gantr# to cantile(er erection -osition


25/43

Fig. $* T)e *5ft /$&D m0 la+nc)ing gantr#

Fig. $ Segment attac)ed to t)e gantr# lifting beam.


26/43

Some of t)e feat+res of t)e trailer !ere=

$. A )#dra+lic s#stem t)at -ro(ided distrib+tion of t)e $5 ton

/$D t0 segment !eig)t to a Gstreet legal load'G -ermitting

tra(el o(er cit# streets.

. T)e ca-abilit# to maintain t)e segment in a le(el -lane e(en

on +ne(en terrain.

&. An Gall !)eels steeringG s#stem' !)ere all t)e !)eels on t)e

trailer !ere s#nc)roni>ed to steer as a +nit' greatl# im-ro(ing

t)e manoe+(rabilit# of t)e trailer.

. T)e abilit# to be connected to t)e -+lling tractor from eit)er

end.

T)e trailer !as -+lled b# a D* )- /&* 1J0 tractor from t)e

casting #ard and escorted b# a -ic18+- tr+c1' (ia cit# streets' to

t)e -ro,ect site. T)ere' t)e con(o# tra(elled o(er a )a+l road

s-eciall# b+ilt to accommodate t)e la+nc)ing gantr# erection

sc)eme. Once be)ind t)e !est ab+tment' t)e tractor !as

disconnected' t+rned aro+nd' and reconnected to t)e ot)er end

of t)e trailer. T)is manoe+(re allo!ed t)e segment to bebac1ed +- on to t)e bridge dec1 and +nder t)e la+nc)ing

gantr#.

Lan!(ing Gantr)

T)e contract dra!ings detailed a beam and !inc) erection

sc)eme. After anal#sing t)e site conditions' Perini8PC28O9:

decided to e-lore alternate erection met)ods. T)e most

-romising sc)eme !as de(elo-ed !it) t)e assistance of Finle#

"cNar# Engineers and consisted of a self8la+nc)ing o(er)ead

gantr#. T)is alternate met)od -resented se(eral ad(antages=

$. It minimi>ed t)e amo+nt of !or1 to be done from t)e

!ater. T)e beam and !inc) met)od !o+ld )a(e re+ired

se(eral marine acti(ities' s+c) as segment trans-orting

facilities' material barges' and se(eral large barge

mo+nted cranes and t+g boats. T)is !o+ld )a(e


27/43

congested t)e ri(er and a?ected t)e recreational and

commercial boating tra3c. T)e la+nc)ing gantr# met)od

re+ired t)e s+--ort of onl# one barge8mo+nted *8ton

/*% t0 :ro(e crane and $$5 ft. /& m0 "anlift.

. It s)ortened t)e -ro,ect d+ration. T)e +se of an o(er)ead

la+nc)ing gantr# allo!ed Perini8PC28O9: to c+t

a--roimatel# one #ear o? t)e constr+ction sc)ed+le b#

-ro(iding a faster s+-erstr+ct+re erection o-eration t)at !as

also less de-endent on t)e ri(er conditions' es-eciall# d+ring

t)e frigid Ne! England !inter mont)s.

T)e la+nc)ing gantr# !as designed b# Fre#ssinet International

in France and b+ilt b# Canron6o+gall in Canada. Otter

Engineering -ro(ided t)e fabrication ins-ection and (ario+s

engineering tas1s. Finle# "cNar# Engineers de(elo-ed t)e

erection sc)eme' coordinated and s+-er(ised t)e gantr# design

and fabrication' and -ro(ided constr+ction engineering ser(ices

t)ro+g)o+t t)e -ro,ect.

T)e gantr# !as abo+t *5ft /$&Dm0 long and !eig)ed

a--roimatel# 55 tons /* t0 /see Figs. $a and $*0. One of t)e c)aracteristics of t)e gantr# !as t)e +se of a )#dra+lic

c#linder to lift t)e segments instead of a !ire ro-e !inc). T)is

feat+re !as (er# +sef+l in setting t)e segments as it allo!ed

t)e o-erator to control t)e transfer of t)e load to t)e str+ct+re.

Pier Co&mn Pre'aration

Se(eral o-erations )ad to be com-leted -rior to t)e start8+- of

t)e s+-erstr+ct+re erection on a gi(en cantile(er s-an. T)ese

o-erations !ere s+--orted b# t)e barge8mo+nted crane. T)ese

tas1s incl+ded=

$. Erecting t)e -ier corbels. T!o -airs of brac1ets !ere

attac)ed and stressed to t)e to- of eac) -ier /see Fig. $D0. Eac)

brac1et s+--orted a )#dra+lic ,ac1. T)ese corbels !ere +sed to

s+--ort t)e gantr# in t)e -ier segment erection -osition' and to


28/43

)el- balance t)e cantile(er d+ring t)e initial constr+ction

stages. T)e corbels also ser(ed as a s+--ort for t)e -latform

aro+nd t)e -ier to-.

. Stressing t)e -ier ca-s. T)is ste- !as re+ired b# t)ebridge design to minimi>e t)e si>e of t)e ca-s and to s+stain

t)e )ig) b+rsting forces from t)e bridge !eig)t.

&. Setting and gro+ting t)e bridge bearings. To s-eed +-

t)e segment erection -rocess' t)e 4oint 7ent+re decided to set

and gro+t t)e bearings a)ead of segment erection in order to

remo(e t)ese acti(ities from t)e critical -at). An acc+rate Gasb+iltG s+r(e# of t)e embedded -lates in t)e -ier segment !as

+sed to calc+late t)e coordinates of t)e bearings on to- of t)e

-ier.

Lan!(ing t(e Gantr) to t(e Next Pier

A detailed ste-8b#8ste- -roced+re and c)ec1list !erede(elo-ed for e(er# stage of t)e la+nc)ing o-erations. T)ese

Gc)ec1s and balancesG !ere +sed to ens+re t)at no ste-s !ere

omitted and to record all t)e -ertinent data d+ring t)e

la+nc)ing o-eration' incl+ding )#dra+lic -ress+res' ,ac1

etensions' and ot)er detail. 2a+nc)ing to t)e -ier !as

accom-lis)ed in @(e ma,or ste-s=

Ste' * 8 "o(ing t)e rear leg to t)e center leg /Fig. $b0.

T)e rear leg anc)ors to t)e dec1 !ere detensioned and s)ims

!ere -laced +nder t)e tr+sses at t)e center leg. T)e a+iliar#

s+--ort !as acti(ated and etended +ntil t)e tail of t)e gantr#

!as lifted )ig) eno+g) so t)e rear leg !as )anging +nder t)e

tr+sses from its rollers. At t)at time' it !as la+nc)ed for!ard

+sing t)e la+nc)ing !inc)es. J)en t)e rear leg reac)ed t)e

segment be)ind t)e center leg' it !as le(elled abo+t $< in. /*D

mm0 from t)e dec1 and t)e a+iliar# s+--ort !as retracted

+ntil t)e gantr# tr+sses rested on t)e rear leg. T)is leg !as


29/43

anc)ored do!n to t)e dec1 !it) eig)t !renc) tig)t $&s in. /&*

mm0 6#!idag bars.

Ste' + 8 "o(ing t)e center leg for!ard /Fig. $c0. S)ims

!ere -laced +nder t)e tr+sses at t)e rear leg. T)e center leganc)ors !ere t)en detensioned. T)e a+iliar# leg !as retracted

+ntil t)e tr+sses started to -i(ot aro+nd t)e rear leg. T)e

tr+sses !ere -i(oted +ntil t)e center leg !as s+s-ended from

its rollers. At t)at time' it !as mo(ed for!ard to its -osition and

le(elled at $< in. /*D mm0 from t)e dec1. T)e a+iliar# leg !as

etended +ntil t)e tr+sses rested on t)e center leg' !)ic) !as

anc)ored do!n to t)e dec1 !it) eig)t !renc) tig)t $&s in. /&*

mm0 6#!idag bars.

Ste' , 8 "o(ing t)e rear leg to its -osition /Fig. $d0.

S)ims !ere -laced +nder t)e tr+sses at t)e center leg. T)e rear

leg anc)ors !ere loosened. T)e a+iliar# leg !as etended +ntil

t)e tr+sses started to -i(ot aro+nd t)e center leg. T)e tr+sses

!ere -i(oted +ntil t)e rear leg !as s+s-ended from its roller. At

t)at time' it !as mo(ed bac1 to its -osition and le(elled at $in. /&* mm0 from t)e dec1. T)e a+iliar# leg !as retracted

+ntil t)e tr+sses rested on t)e center leg' !)ic) !as also

anc)ored do!n to t)e dec1 !it) eig)t $&s in. /&* mm0

6#!idag bars stressed to $55 1i-s /* 1N0 eac).

Ste' - 8 2a+nc)ing t)e gantr# to

t)e -ier /Fig. $e0. T)e

a+iliar# leg !as com-letel# retracted. T)e s)ims !ere

remo(ed from +nder t)e tr+sses and t)e tr+sses !ere set onrollers. T)e gantr# !as la+nc)ed for!ard to!ard t)e net -ier.

Ste' * 8 Acti(ating t)e front leg. J)en t)e front leg !as

on to- of t)e +- station corbel of t)e -ier' it !as etended and

loc1ed to t)e corbel. T)e -ress+re in t)e front leg ,ac1s !as

incrementall# increased +ntil abo+t $55 1i-s /* 1N0 !ere

transferred to t)e corbels. At t)at stage' t)e ,ac1s !ere sec+red

and s)ims +nder t)e tr+sses !ere installed at t)e rear leg. For


30/43

s-ans s)orter t)an 5 ft. /D& m0' in Ste- $ t)e rear leg !as

mo(ed to its @nal -osition and Ste-s and & !ere omitted.

Fig. $D Pier corbels and -ier ca- are read# to recei(e t)e )ea(# -ier

segment.

Fig. $< Second segment at -ier


31/43

Fig. $% connecting t)e erection -osttensioning bars

Fig. 5 A--l#ing e-o# ad)esi(e to t)e ,oints bet!een segments


32/43

Fig. $ Second segment -ost8tensioned to -ier segment.

Ere!ting t(e "irst T#o Segments .T(e Pier

Ta/&e0

After -ositioning t)e -ier segment +nder t)e tail of t)e gantr#'

t)e segment !as connected to t)e lifting beam b# eig)t $&s in.

/&* mm0 6#!idag bars /see Fig. $0. T)e bars -assed t)ro+g)

slotted )oles in t)e lifting beam and t)e longit+dinal slo-e of

t)e segment !as -reset b# (ar#ing t)e -osition of t)e bars in

t)e slotted )oles. T)e segment !as t)en lifted and trans(ersel#

le(elled +sing t)e trans(erse le(elling ,ac1 on t)e lifting beam.

T)e segment !as raised and carried to t)e -ier !)ere it !as

rotated %5 degrees and lo!ered on to- of t)e bearings /see Fig.

$D0. A s+r(e# cre! !as +sed to g+ide and (erif# t)e -osition of

t)e segment. T)e bearings !ere bolted to t)e embedded -late

in t)e -ier segment.

After com-letel# transferring t)e load to t)e bearing' t)e -ier

segment !as stressed do!n to t)e -ier and t)e lifting trolle#!as disconnected and tra(elled bac1 to t)e tail of t)e gantr# to


33/43

-ic1 +- t)e net segment. T)e second segment !as bro+g)t in'

lo!ered and -ositioned abo+t ft. /$5 mm0 from its @nal

-osition on t)e do!nstation side of t)e -ier /see Fig. $


34/43

t)e -ro-er clos+re of t)e ,oint. A si>able bead of e-o#

s+ee>ed o+t all aro+nd t)e ,oint' indicating t)at t)e ,oint !as

-ro-erl# sealed.

After t)e erection -ost8tensioning bars !ere loc1ed in -lace anda random lift8o? c)ec1 !as -erformed' t)e ,ac1s bet!een t)e

segment and t)e corbels !ere etended to to+c) t)e bottom of

t)e segment and -ress+ri>ed to *55 -si /&. "Pa0 /see Fig. $0.

At t)is -oint' t)e gantr# o-erator started to release t)e load

incrementall#. After a @nal c)ec1 of t)e ,oint' t)e erection -ost8

tensioning ,ac1s !ere remo(ed.

Immediatel# after disconnecting t)e lifting beam' all t)e em-t#

-ermanent -ost8tensioning d+cts !ere s!abbed in order to

clean and Latten t)e bead of e-o# t)at formed inside t)e d+ct

/see Fig. 0. If not cleaned' t)is bead !o+ld )a(e red+ced t)e

e?ecti(e diameter of t)e d+ct and ca+sed serio+s -roblems

d+ring installation of t)e tendons and -ossible tendon bloc1age

d+ring t)e gro+ting o-erations.

Fig. & s)o!s a -ier !it) t)e -ier segment and ad,acent

segments in -lace' and t)e net segment being mo(edlongit+dinall# o(er t)e co+nter!eig)t. After a n+mber of

segments !ere -laced' t)e gantr# !as -re-ared for la+nc)ing

to t)e cantile(er erection -osition from !)ic) t)e remainder of

t)e s-an !as erected.


35/43

Fig. cleaning o+t -ost8tensioning d+cts

Lan!(ing t(e Gantr) to t(e Canti&e1er Ere!tion

Position

2a+nc)ing t)e gantr# to t)e cantile(er erection -osition !as

accom-lis)ed in t)ree ma,or ste-s=

Ste' 2 8 "o(ing t)e rear leg to t)e center leg /Fig. $f0. T)e

rear leg !as mo(ed for!ard as described in Ste- $ and

anc)ored to t)e dec1 b# stressing t)e 6#!idag bars.

Ste' D 8 "o(ing t)e center leg to t)e -ier segment /Fig. $g0.

T)e center leg anc)ors !ere loosened. T)e front leg !as

acti(ated and etended +ntil t)e tr+sses started to -i(ot on t)e

rear leg and t)e center leg became s+s-ended from t)e

tr+sses. At t)at time' it !as mo(ed for!ard to t)e -ier segment

and le(elled $ in. /&5* mm0 from t)e dec1. T)e front leg !as

retracted +ntil t)e tr+sses rested on t)e center leg' !)ic) !as

anc)ored do!n to t)e dec1 b# stressing t)e 6#!idag bars.

Ste' 3 8 2a+nc)ing t)e tr+sses to t)e cantile(er -osition /Fig.

$)0. T)e s)ims !ere remo(ed from +nder t)e tr+sses at t)e

rear leg and t)e tr+sses !ere set on rollers. T)e tr+sses !erela+nc)ed for!ard +ntil t)e 1ing -ost !as abo(e t)e center leg.


36/43

S-ecial s)ims !ere installed +nder t)e tr+sses at t)e center leg

and t)e gantr# !as read# to erect t)e remaining segments in

t)e cantile(er.

Fig. & Pier table com-lete and segments for cantile(ers mo(ing o+t from

-ier

T)'i!a& Ba&an!ed Canti&e1er Segment Ere!tion

T)e @rst segment +- station of t)e -ier !as bro+g)t in and

erected in t)e same manner as t)e do!nstation segment. T)e


37/43

-ermanent -ost8tensioning tendons' !)ic) !ere -refabricated

on t)e bridge dec1' !ere -+lled into t)e d+ct /see Fig. 0. T)e

7S2 -osttensioning s#stem !as +sed to stress t)e m+lti8strand

tendons.

T)e segment erection contin+ed /Fig.*0 b# alternating t)e

segments bet!een t)e do!nstation and +- station of t)e -ier

!it) some (ariations' s+c) as=

$. A $*8ton /$$& t0 co+nter!eig)t !as -laced on t)e dec1

after erection of t)e t)ird segment. T)is co+nter!eig)t !as

+sed to )el- balance t)e dec1 in t)e +nbalanced stages. T)eco+nter!eig)t !as mo(ed t)ree times to (ar#ing locations

d+ring a t#-ical s-an constr+ction.

Fig. inserting -ermanent -ost8tensioning tendons into d+cts


38/43

Fig. * Cantile(er erection b# alternatel# -lacing segments left and rig)t

of t)e -ier

Fig. :antr# stabili>ers are connected to t)e dec1.


39/43

Fig. D. Final ad,+stments at t)e clos+re ga-.

. After erecting t!o segments on eit)er side of t)e -ier' t)e

la+nc)ing gantr# stabili>ers !ere connected to t)e dec1 to

stabili>e t)e s+-erstr+ct+re d+ring t)e +nbalanced constr+ction

stages /see Fig. 0. T)e ,ac1s on t)e corbels !ere released at

t)at time. T)e stabili>ers !ere mo(ed se(eral times d+ring at#-ical s-an constr+ction.

&. In addition to t)e to- slab cantile(er tendons' some of t)e

longer s-ans re+ired t)e installation and stressing of dra-ed

tendons. T)ese tendons !ere anc)ored in t)e str+t bloc1s and

!ere de(iated in t)e -ier segment dia-)ragm.


40/43

Fig.


41/43

bearings on t)e net -ier ca-. :ro+ting o-erations started after

t)e gantr# !as la+nc)ed /see Fig.


42/43

-ro(iding e-erienced engineers and s+-er(ision to t)e -ro,ect

sta? and to ac+iring t)e necessar# o+tside engineering

assistance to meet t)e tec)nical c)allenges of t)e -ro,ect.

Fig. &5. Ra#mond E. Bald!in Bridge nearing com-letion

T)e 4oint 7ent+re contracted !it) t)e engineering @rm of Finle#

"cNar# Engineers' 6en(er' Colorado' to -ro(ide constr+ction

engineering ser(ices for t)is -ro,ect. T)is @rm !as c)osen

beca+se of its s-eciali>ed tec)nical ca-abilities' )ig)l# regarded

re-+tation !it)in t)e segmental bridge ind+str#' and

commitment to t)e -ro,ect.

T)e @rm -rod+ced t)e necessar# integrated s)o- dra!ings for

eac) of t)e


43/43

integrated s)o- dra!ings for eac) segment is (er# bene@cial to

t)e -rod+ction of +alit# com-onents.

Finle# "cNar# Engineers also -ro(ided t)e contractor !it) a

geometr# control -ac1age to assist t)em in acc+ratel# casting

t)e segments to t)e -ro-er )ori>ontal and (ertical alignment.

T)e# +sed t)eir in8)o+se com-+ter -rogram to calc+late before

casting set+- ele(ations for eac) segment. After casting'

ele(ations !ere t)en in-+t into t)e -rogram to -rod+ce as8cast

geometr# and t)en set+- ele(ations for t)e net segment to be

cast. T)e @nal as8cast information for eac) cantile(er !as t)en

in-+t into t)e -rogram to -rod+ce constr+ction ele(ations for

balanced cantile(er segment erection.

T)e s+ccess of most -recast concrete segmental str+ct+res

relies on t)e timel# -rod+ction of +alit# -recast bo girder

segments. No matter )o! a+tomated and e3cientl# carried o+t

t)e erection is' t)e o(erall +alit# of a segmental str+ct+re

de-ends on t)e -rod+ction of )ig) +alit# -recast elements

fabricated to t)e -ro-er bridge geometr#. PC2' Edmonton'Canada' bro+g)t t)e re+ired segmental e-erience to t)e

-ro,ect team t)at !as necessar# to ac)ie(e s+ccess.

In t)e $%

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Parsons Brinckerhoff Consruction

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